5-FU cream is a treatment that selectively destroys sun-damaged cells in the skin whilst retaining the normal healthy skin cells. It has been in use for more than 50 years.

5-FU cream will induce inflammation in the skin. This will consist of redness, soreness, oozing, crusts and scabs. After completing the treatment course this reaction will settle over a few weeks. Sometimes your doctor may recommend using a steroid cream to help settle the inflammation more quickly.

In the UK, two forms are available: 5% 5-FU cream (Efudix^®) and 0.5% 5-FU combined with 10% Salicylic acid (Actikerall^®).

• 5-Fluorouracil cream - printable version

Acitretin is a type of drug called a retinoid. Retinoids are closely related to Vitamin A and work by slowing down cell growth in the skin. 

• Acitretin - printable version

Acne is a very common skin condition identified by the presence of comedones (blackheads and whiteheads) and pus-filled spots (pustules). It usually starts during puberty. Acne ranges from a few spots on the face, neck, back and chest, which most teenagers will have at some time, to a more severe problem that may cause scarring and reduce self-confidence. For most, it tends to go away by the early to mid twenties, but it can go on for longer. Acne can also develop for the first time in people in their late twenties and beyond.

Occasionally, young children will develop blackheads and/or pustules on the cheeks or nose.

• Acne - printable version

Actinic keratoses are areas of sun-damaged skin found predominantly on sun-exposed parts of the body, particularly the forearms, backs of the hands, face, ears, bald scalp and the lower legs. They may also occur on the lips. The terms actinic andsolar arefrom the Greek and Latin respectively, meaning ‘sunlight-induced’. The term keratosis refers to thickened skin.

• Actinic Keratoses - printable version

The term 'actinic prurigo’ is the term used for a rare (less than 1:1,000) type of skin sensitivity induced by sunlight (photosensitivity); 'actinic' is Greek for 'sunlight', ‘pruritus’ is the medical term for itching, and ‘prurigo’ is a related word which describes the changes that appear in the skin after it has itched and been scratched for a long time. In actinic prurigo the skin becomes firm, raised and itchy on the areas of the skin surface which are exposed to the sun. 

• Actinic prurigo - printable version

Adalimumab is a powerful drug that has been specially designed to mimic normal human molecules, and for this reason it is classed as a ‘biological’ drug. It reduces inflammation by inhibiting the activity of a chemical ‘cytokine’ in the body called ‘tumour necrosis factor alpha’ (TNF-alpha). 

• Adalimumab - printable version

Alitretinoin (brand name Toctino) belongs to a group of drugs called retinoids, which are closely related to vitamin A. It works by reducing skin cell turnover and also helps to reduce skin inflammation.

• Alitretinoin - printable version

Alopecia is a general term for hair loss. Alopecia areata is a common cause of non-scarring (does not cause scarring to the scalp) hair loss that can occur at any age. It usually causes small, coin-sized, round patches of baldness on the scalp, although hair elsewhere such as the beard, eyebrows, eyelashes, body and limbs can be affected. In some people larger areas are affected and occasionally it can involve the whole scalp (alopecia totalis) or even the entire body and scalp (alopecia universalis).

It is not possible to predict how much hair will be lost. Regrowth of hair in typical alopecia areata is usual over a period of months or sometimes years, but cannot be guaranteed. The chances of the hair regrowing are better if less hair is lost at the beginning. Most people, with only a few small patches get full regrowth within a year. If more than half the hair is lost then the chances of a full recovery are not good. The hair sometimes regrows white, at least in the first instance. Most people get further attacks of alopecia areata. In alopecia totalis and alopecia universalis, the likelihood of total regrowth is less.

• Alopecia areata - printable version

Apremilast is an oral medication which works by inhibiting (stops it from working as it usually does) an enzyme known as phosphodiesterase inhibitor (PDE4). PDE4 controls the inflammation process in the skin. Reducing or controlling the inflammation in the skin can lead to improvement of symptoms in people with psoriasis. 

• Apremilast

Atopic eczema is a common skin condition and may start at any age, but the onset is often in childhood: 1 in every 5 children in the UK are affected by eczema at some stage.

The term ‘atopic’ is used to describe a group of conditions, which include asthma, eczema and hay-fever¹. These conditions are all linked by an increased activity of the allergy reaction of the body’s immune system. ‘Eczema’ is a term which comes from the Greek word ‘to boil’ and is used to describe red, dry, itchy skin which sometimes weeps, blisters, crusts, scales and thickens.

• Atopic eczema - printable version

An Atypical Fibroxanthoma (AFX) is an uncommon type of skin cancer, accounting for less than 0.2 % of all skin cancers. It occurs mainly on the head or neck of older people, usually after the skin has been damaged by prolonged exposure to sunlight.

• Atypical fibroxanthoma - printable version

Atypical mole syndrome is a disorder of the skin which is seen in approximately 2% of the population. It is defined when an individual has more than 50 moles composed of melanocytes (pigment producing skin cells) present on their skin, and three or more are atypical (unusual) in their appearance, such as their size, shape or colour. An atypical mole is one greater than 5 mm in diameter, often with flat and raised areas, oval rather than round, and with some colour variation.

Solitary atypical moles are individually benign moles with a low risk of progression to melanoma (a type of skin cancer). However, people with multiple atypical moles (atypical mole syndrome) are considered to have a higher risk (increased 7 to 10-fold) of developing melanoma compared to the general population, due to the presence of atypical moles especially if some of these moles are on the scalp, buttocks, or feet. The risk is increased further if one or more first or second degree relatives (i.e. a close blood relative including parents, full siblings or children, or a blood relative including grandparents, grandchildren, aunts, uncles, nephews, nieces or half-siblings, respectively) have been diagnosed with malignant melanoma; this combination is known as familial atypical mole syndrome.

• Atypical mole syndrome - printable version

Azathioprine has been available since the 1960s. It was developed initially to stop rejection of transplanted organs, such as kidneys. It is now used to treat a wide range of illnesses. It works by suppressing the body’s own defence system (the immune system), either by itself or in combination with other drugs. Azathioprine is not a steroid and is considered to be safer in the long-term than steroid tablets.

• Azathioprine - printable version

A basal cell carcinoma (BCC) is a type of skin cancer. There are two main types of skin cancer: melanoma and non-melanoma skin cancer. BCC is a non-melanoma skin cancer, and is the most common type (greater than 80%) of all skin cancer in the UK. BCCs are sometimes referred to as ‘rodent ulcers’. 

• Basal cell carcinoma - printable version

‘Naevus’ is the Latin word for birthmark. It is called Becker’s after the name of the American Dermatologist that described it.Becker’s naevus is sometimes called ‘Becker's melanosis’ or ‘pigmented hairy epidermal naevus’.

Becker’s naevus usually develops in the second or third decade of life. It can occur in all skin types and is more common in boys than girls. Although most commonly people will only have one Becker’s naevus, it is possible to have more.

• Becker's naevus - printable version

Blue rubber bleb naevus syndrome has also been called ‘Bean syndrome’ after Dr William Bean, who described it. It is caused by the congenital development of multiple venous malformations in the skin, soft tissues and gastrointestinal tract (intestine).

A ‘syndrome’ is a group of signs and symptoms that occur together. ‘Naevus’ is Latin for ‘birthmark’. The ‘blue rubber blebs’ are small areas of blue mis-shaped veins with a rubber-like feel.

In some people, blebs are only seen in the skin. They can also occur in any other part of the body, most commonly the intestine.

• Blue rubber bleb naevus - printable version

A boil, or furuncle, is an abscess (infection) of the skin or in the deep part  hair follicles. The infection is usually caused by bacteria called Staphylococcus aureus (S. aureus). Occasionally the infection may spread into the surrounding tissues (cellulitis) and can cause fever and a feeling of being unwell. When several boils form close together and join, this is known as a carbuncle. Sometimes rarer types of S. aureus: Methicillin resistant Staphylococcus aureus (MRSA) and Panton-Valentine leukocidin (PVL), can cause boils. PVL may cause larger and more painful boils (see Patient Information Leaflet on PVL Staphylococcus Aureus (PVL-SA) skin infection).

The bacteria causing the boil can occasionally spread from one part of the body to another and from one person to another by skin-to-skin contact and from clothing and towels which have been contaminated with pus from the boil. This is especially true when boils are caused by the PVL strain of S. aureus bacteria. Boils are common in teenagers and can affect boys more often than girls. Sufferers of boils do not usually have a problem with their immune system, but boils can be more severe in patients with a suppressed immune system. Boils are more common in patients with diabetes and those who are overweight. 

• Boils - printable version

Squamous cell carcinoma in situ, often called Bowen’s disease, is a growth of cancerous cells that is confined to the outer layer of the skin. It is not a serious condition, and its importance rests on the fact that, very occasionally, it can progress into an invasive skin cancer known as squamous cell carcinoma (see Patient Information Leaflet on Squamous Cell Carcinoma for further information). For this reason, dermatologists usually treat, or at least monitor, Bowen's disease. Squamous cell carcinoma in situ, often called Bowen’s disease, is a growth of cancerous cells that is confined to the outer layer of the skin. It is not a serious condition, and its importance rests on the fact that, very occasionally, it can progress into an invasive skin cancer known as squamous cell carcinoma (see Patient Information Leaflet on Squamous Cell Carcinoma for further information). For this reason, dermatologists usually treat, or at least monitor, Bowen's disease.

• Bowen's Disease - printable version

Brodalumab is a biologic medicine that has been designed to treat psoriasis. It works by specifically targeting a chemical messenger (known as a ‘cytokine’) in the body called ‘interleukin-17A’ (IL-17A). We know that IL-17A is one of the main causes of inflammation in psoriasis, and by blocking it brodalumab can improve symptoms of psoriasis. 

• Brodalumab

There are two types of topical calcineurin inhibitors called tacrolimus ointment (Protopic 0.03% and 0.1%) and pimecrolimus cream (Elidel). They are classified as immunomodulating agents.  This means that they act on the immune system to reduce skin inflammation. Both tacrolimus and pimecrolimus block a chemical called calcineurin which activates inflammation in the skin and causes redness and itching of the skin.

• Calcineurin inhibitors - printable version

Capillaritis is a harmless skin condition also known as pigmented purpura. It is usually seen as reddish-brown areas of skin often on the lower legs.

• Capilliritis

The “vulva” is the term used to describe the visible part of the female genitalia which includes the inner and outer “lips” (labia) and clitoris.

• Care of vulval skin - printable version

Erysipelas and cellulitis are common infections of the skin. Erysipelas is a superficial infection, affecting the upper layers of the skin, while cellulitis affects the deeper tissues. They can overlap, so it is not always possible to make a definite diagnosis between the two. 

• Cellulitis and erysipelas - printable version

Alopecia is a general term for hair loss. Central centrifugal cicatricial alopecia (CCCA) is a type of permanent hair loss that often starts on the top of the scalp and spreads outwards. Other names for CCCA include ‘Follicular Degeneration Syndrome’ and ‘Hot-comb alopecia’.              

CCCA is the most common form of permanent hair loss seen in women of African descent, mainly beginning around the ages of 30-40 years. Very occasionally, it may also affect men.

• Central centrifugal cicatricial alopecia - PRINTABLE

Chondrodermatitis nodularis is inflammation of the skin of the ear. This Latin/Greek name literally means an inflammation both of the cartilage (chondro-) and of the skin (-dermatitis) causing a bump (a nodule, hence nodularis).

It is common and harmless, but can be tender when touched. 

• Chondrodermatitis nodularis - printable version

The term ‘chronic actinic dermatitis ‘or ‘CAD’ is used to describe an unusual type of eczema or dermatitis that is caused by abnormal skin sensitivity to sunlight (photosensitivity). CAD usually lasts for several years. ‘Chronic’ means the condition can last a long time, ‘Actinic’ means sunlight is involved and ‘dermatitis’ means inflammation of the skin.

• Chronic actinic dermatitis - printable version

Paronychia is a common infection of the skin around the finger or toenails (the nail folds). There are two types - ‘acute paronychia’ develops quickly and lasts for a short period of time; and ‘chronic paronychia’ develops slowly, lasting for several weeks and often comes back. Chronic paronychia is not caught from someone else. 

• Chronic paronychia - printable version

Like penicillin, ciclosporin is a substance produced by a fungus. Ciclosporin suppresses the immune system and was initially developed for transplant patients to prevent them rejecting their kidneys and other organs. It was later found to benefit some patients with diseases caused by immune reactions. 

• Ciclosporin - printable version

Colchicine is an extract of the plant Colchicum autumnale (autumn crocus). It has been used as a medicine since ancient times.

Colchicine changes the response of the immune system. It has been found to be helpful in conditions where a person has too many neutrophils (a type of white blood cell) in the skin.

• Colchicine - printable version

Congenital dermal melanocytosis is a common, harmless, pigmented birthmark. It is sometimes also called lumbrosacral dermal melanocytosis, and is sometimes still referred to by its old name of a Mongolian Blue Spot.   It is usually seen at birth or shortly afterwards. It typically disappears before the age of 6. 

• Congenital dermal melanocytosis - printable version

Congenital erythropoietic porphyria (CEP), also called Günther’s disease after the doctor who first described it, is the rarest of the porphyrias. It is estimated that about 1 in every 2-3 million people are affected by CEP, which affects males and females equally, and occurs in all skin types.

The word ‘congenital’ means a condition that exists at birth and often before birth, or that develops during the first month of life; ‘erythropoietic’ means associated with red blood cells and their formation.

• Congenital erythropoietic porphyria - printable version

Dermatitis describes a type of inflammation of the skin. Dermatitis and eczema mean the same thing. Contact dermatitis describes inflammation that is caused by direct skin contact with something in your environment. It is sometimes called contact eczema.

• Contact dermatitis - printable version

The term ‘cryotherapy’ literally means ‘treatment using low temperature’ and refers to the removal of skin lesions by freezing them. The most common product used by doctors is liquid nitrogen.

• Cryotherapy - printable version

Amyloidosis or ‘amyloid’ is group of rare diseases in which abnormal proteins, accumulate in various organs including the skin. The name ‘amyloid’ was given to the condition over 150 years ago because the deposits looked like starch under the microscope. (In Latin amylum = starch).

In primary localised cutaneous amyloidosis (PLCA) amyloid deposits only occur in the skin. The exception to this is a rare disease called nodular amyloid, which can be associated with amyloid deposits in other body organs and myeloma (a form of bone marrow cancer).

PLCA is uncommon in Europeans and occurs more frequently in people who originate from South-East Asia, South America and the Middle East. It usually starts in adult life and tends to persist for many years. 

There are three main forms of PLCA: Macular amyloidosis, lichen / papular amyloidosis and Nodular amyloidosis (the rarest form).

• Cutaneous amyloidosis - printable version

Vasculitis is a term referring to inflammation of blood vessels; these may be arteries, veins or both, and can affect any part of the body. When vasculitis affects small or medium sized blood vessels in the skin, it is known as cutaneous vasculitis. Occasionally cutaneous vasculitis can be a sign of inflammation occurring in other organs (a systemic vasculitis) and further investigation may be required for a full diagnosis.

• Cutaneous vasculitis - printable version

CCS is a rare genetic condition which causes patients to develop multiple benign skin tumours on the scalp and body. The benign skin tumours may be called cylindromas, spiradenomas or trichoepitheliomas, and some patients may have a combination of these tumours. Cylindromas are benign skin tumours that arise from hair follicles, which present as pink lumps on the scalp and trunk. Spiradenomas are benign skin tumours that are often painful, and can have a blue or black colour, and are related to cylindroma. Features of cylindroma and spiradenoma can often be found in a single skin lump in patients with CCS. Trichoepithelioma are skin-coloured small lumps often seen on the skin around the nose.

• CYLD cutaneous syndrome - printable version

By definition, cyst is a closed sac that has two main features:

•       A lining

•       Contents that are liquid or semi-solid

The lining. Differences between the lining of epidermoid and pilar cysts can be seen under the microscope:

•       The lining of an epidermoid cyst looks like the epidermis (the outermost layer of cells in the skin)

•       The lining of a pilar cyst is made up of cells like those found in the roots of hairs

The contents. Both types of cyst contain a cheesy material, looking rather like white toothpaste. This is made of keratin - the material that makes up hair and the outer layer of the skin.

In the past, pilar and epidermoid cysts were wrongly known as ‘sebaceous’ cysts but this term should be used only for a quite different and much less common type of cyst that is filled with a clear oily liquid made by sebaceous (grease) glands.

Epidermoid and pilar cysts are common, not cancerous, and not contagious.

• Epidermoid and pilar cysts - printable version

Dapsone is a sulphonamide antibiotic. It is available only on prescription. It acts as an anti-inflammatory drug and has been used successfully as a treatment for several skin conditions such as dermatitis herpetiformis, pyoderma gangrenosum, Sweet’s syndrome and vasculitis for many years. It can, under supervision of your dermatologists, also be used for other inflammatory skin conditions that are not mentioned here if none of the standard treatments are effective.

• Dapsone - printable version

It is a rare inherited skin condition, estimated to affect 1 to 4 people per 100,000 of the population and is characterised by a change in the way skin cells (keratinocytes) stick together within the upper layer of the skin (epidermis). This leads to changes in the skin and nails, and sometimes inside the mouth can be affected. Other names for Darier disease include Darier-White disease and Keratosis Follicularis.

• Darier's disease - printable version

Dermatitis herpetiformisis a rare, very itchy and persistent blistering skin condition, affecting between 0.4 and 3.5 people per 100,000 of the European population. It typically affects Caucasians aged between 15-40 years and is more common in men, but can occur in all age and racial groups.

• Dermatitis herpetiformis - printable version

A dermatofibroma is a common overgrowth of the fibrous tissue situated in the dermis (the deeper of the two main layers of the skin). It is benign (harmless) and will not turn into a cancer. Whilst dermatofibromas are harmless, they can be similar in appearance to other concerning skin tumours. It is therefore important to see a health professional for a diagnosis.

• Dermatofibroma - printable version

DFSP is a very rare type of skin cancer. It usually occurs on the trunk, often the chest and shoulders; however, it can also affect the limbs, head and neck and rarely the genitalia. It starts in the deep layer of the skin (the dermis) and can spread to surrounding structures such as fat and muscle. Although it grows very slowly, it can become quite large. It can often be completely removed with a wide margin of normal tissue, or with a specialised form of surgery called Mohs surgery. DFSP can come back even if completely removed by surgery. It is very rare for DFSP to spread to other parts of the body (occurring in approximately 5% of cases).

• Dermatofibrosarcoma protuberans - printable version

Dermatomyositis is a rare condition that causes inflammation in both the skin and the muscles. The word comes from the Latin for skin (dermis), muscles (myos) and inflammation (-itis). In rare cases, only the skin is affected and not the muscles.

• Dermatomyositis - printable version

A digital myxoid cyst (sometimes called a mucous cyst) is a non-cancerous swelling that occurs on the fingers or, sometimes, the toes.The cyst is often connected to the lining of the finger or toenail joint, and is usually located between the joint and the nail.

Digital myxoid cysts are not contagious and are not a form of skin cancer.

The term cyst is from the Greek kystis meaning a bag or pouch; myxoid and mucoid refer to the jelly-like contents. Digital derives from the Latin digitus, meaning finger or toe. A small number of people might develop these because of excessive repetitive finger motion.

• Digital myxoid cyst - printable version

Fumaric acid esters (FAEs) are chemical compounds that have been used as a treatment of psoriasis for over 30 years. The licensed FAE for treatment of moderate to severe plaque psoriasis in the UK is Skilarence® which contains dimethylfumarate (DMF), the main active ingredient.

• Dimethyl fumarate (Fumaric acid esters ) - printable version

• Discoid eczema - printable version

DLE is an uncommon skin rash, usually made worse by exposure to sunlight. The term ‘lupus erythematosus’ is applied to a range of related disorders. ‘Discoid’ lupus erythematosus is confined to the skin and is not associated with symptoms from other organs. A more severe form is called ‘systemic’ lupus erythematosus, which can affect internal organs. 

• Discoid lupus erythematosus - printable version

Dissecting cellulitis of the scalp is a rare inflammatory scalp condition. Pus-filled spots and lumps develop with subsequent hair loss over the affected area. Hair loss is permanent due to the inflammation which destroys the hair follicles and leaves scar tissue.

The condition is occasionally referred to as perifolliculitis capitis abscedens et suffodiens. It usually affects darker-skinned adult men, especially those of Afro-Caribbean origin, but can affect any race, sex or age.

• Dissecting cellulitis - printable version

DSAP is a skin condition with multiple, dry, scaly rings, each measuring up to 1 cm (1/2 inch) across. They are found mainly on the forearms and legs, in sun-exposed sites. It is sometimes confused with actinic keratosis which is also caused by sun exposure (See Patient Information Leaflet on Actinic Keratoses); however, actinic keratosis is more likely to arise on the face and hands.

DSAP is twice as likely to develop in women compared with men and is more common in lighter skin type. Itnormally develops between 30-50 years of age. It is not contagious.

There are multiple other types of porokeratosis, which affect different age groups or present in slightly different ways.

• Disseminated superficial actinic porokeratosis - printable version

Dupilumab is a biologic medicine that has been designed to treat eczema. It works by reducing inflammation. It works on chemical messengers (known as a ‘cytokines’) in the body called ‘interleukin-4’ (IL-4) and ‘interleukin-13’ (IL-13).

• Dupilumab - printable version

Dystrophic epidermolysis bullosa (DEB) is a rare inherited skin disorder. The skin of people with DEB is more fragile than normal. Minor injury causes blisters or ulcers that may be slow to heal and often leave scars. DEB can be mild, but it can also be severe, affecting the mouth, oesophagus (gullet), eyes and nails in addition to the skin.

Dystrophic epidermolysis bullosa (DEB) is divided into two main types depending on how it is inherited: recessive dystrophic epidermolysis bullosa (RDEB) and dominant dystrophic epidermolysis bullosa (DDEB)..

There are other forms of inherited epidermolysis bullosa (EB), including epidermolysis bullosa simplex, junctional epidermolysis bullosa and Kindler Syndrome. These are all distinct skin diseases so people who have DEB do not develop other types of epidermolysis bullosa at a later date.

• Dystrophic epidermolysis bullosa - printable version

Eccrine porocarcinoma is a rare type of skin cancer involving a type of sweat gland called the eccrineglands. Eccrine sweat glands are present in theskin, with the highest density on the palms, soles,face and scalp.

Eccrine porocarcinoma is typically a slow-growing tumour which is more common in those who are over 60 years of age, and occurs equally in men and women. It can sometimes spread to internal organs in the body.

• Eccrine porocarcinoma - printable version

Atopic eczema is a very common skin condition due to skin inflammation. It may start at any age but the onset is often in childhood. 1 in every 5 children in the UK is affected by eczema at some stage. It may also start later in life in people who did not have AE as a child.

The term ‘atopic’ is used to describe a group of conditions, which include asthma, eczema and hay-fever and food allergy. These conditions are all linked by an increased activity of the allergy side of the body’s immune system. ‘Eczema’ is a term which comes from the Greek word ‘to boil’ and is used to describe red, dry, itchy skin which can sometimes become weeping, blistered, crusted, scaling and thickened.

Eczema herpeticum is a potentially serious viral infection which can spread to large areas of the skin. It most commonly affects people with atopic eczema but may also affect those with other inflammatory skin conditions. 

• Eczema herpeticum - printable version

Epidermolysis bullosa (EB) simplex is a rare inherited disorder in which the skin is fragile and blisters at sites of rubbing. It is mild in the usual form; blisters tend to be confined to the palms and soles, and are most troublesome during warm weather. In other types the blistering may be more generalised and occasionally blisters arise in the mouth. The most severe form is called generalised severe EB simplex (Dowling-Meara) and those affected have more widespread blistering which occurs throughout the year.

EB simplex is different from other types of EB which include junctional, dystrophic and Kindler forms; if you have EB simplex then you will not go on to develop these other types. EB simplex is not an infection, it is not contagious, and it is not due to an allergy.

• Epidermolysis bullosa simplex - printable version

Erosive (presenting with superficial ulcerations/erosions) pustular(pus forming) dermatosis(skin problem) is a long-term skin disease of scalp and legs. Women develop it three times more often than men. EPD most commonly develops in the elderly.

• Erosive pustular dermatosis - printable version

Erythema multiforme is usually mild - 'erythema multiforme minor' – with only skin involvement, and clearing up in days to weeks. There is also a rare but more severe type, 'erythema multiforme major', which has similar skin features to EM minor, but additionally there is involvement of one or more mucosal membrane (e.g. the lips, the inside of the mouth, the windpipe, the gullet, the anus or genital area, and the eyes) and usually some associated symptoms, such as fever or joint pain.

• Erythema multiforme - printable version

Erythema Nodosum (EN) is a skin condition that is characterised by painful red, rounded lumps which appear on the shins and around the ankles, and less commonly the thighs and forearms. It can occur at any age, in both sexes, and in anyone.These lumps tend to heal to leave a bruise-like appearance. EN is more common among females and is more frequently observed between the ages of 20 and 30 years. 

• Erythema Nodosum

Erythromelalgia is a rare condition. In ancient Greek, ‘Erythros’ means ‘red’ and ‘melalgia’ means pain in a limb.  It can cause episodes of intense burning pain, painful swelling and redness of the feet or hands. Sometimes the legs and arms can be affected, or, less often, other areas such as the ears or face. It usually affects both sides of the body. Females are more commonly affected than males. Erythromelalgia is seen in skin types.  

• Erythromelalgia - printable version

The word ‘erythropoietic’ means associated with red blood cells (‘erythro-’) and their formation (‘-poietic’). The porphyrias are a group of uncommon diseases caused by something going wrong with the production of chemicals known as porphyrins. These chemicals are the building blocks of haem, which, when combined with a protein (globin), forms haemoglobin, the material in red blood cells that carries oxygen round the body. In the case of EPP and XLDPP, there is a build-up of one of these porphyrins (protoporphyrin) in the blood, especially in the red blood cells. This leads to a sensitivity to sunlight. 

• Erythropoietic protoporphyria and X-linked dominant protoporphyria - printable version

Etanercept is one of the first of a group of modern drugs called ‘biologics’ or ‘biologicals.’ Unlike ordinary drugs which can usually be made from chemicals in a test tube, biologics are complex molecules made by living cells. They are designed to mimic or change processes in the human body and are used to treat a range of diseases from cancer to arthritis.

Etanercept blocks the effect of tumor necrosis factor alpha (TNF-alpha) so it is called an ‘anti-TNF’ drug. TNF-alpha helps the body fight infection and cancer, but when over produced it can have harmful effects. Over-production of TNF occurs in several diseases including Crohn’s disease, psoriasis and inflammatory arthritis, so anti-TNF drugs have been as treatment.

• Etanercept - printable version

Extra-mammary Paget’s disease (EMPD) is a rare, slow-growing disease that is a pre-invasive form of skin cancer. It looks similar to a patch of eczema and usually affects skin in the genital area and around the anus. It is commonest in people aged over 50, with studies showing it peaks at around age 65. It is less common in males and in skin of colour.

Primary EMPD arises from cells in the skin, whilst secondary EMPD is due to spread of pre-cancerous or cancerous cells from nearby or distant organs/regions, most commonly the opening to the bladder (urethra), cervix, bladder or bowel.

Paget’s disease, in contrast, refers to the same type of changes occurring in the breast or nipple.There is no relation between EMPD and another disease called Paget’s disease of the bone.

• Extramammary Paget's Disease - printable version

Hairs are formed within the skin in tiny structures known as hair follicles. The word folliculitis describes inflammation of hair follicles and may happen anywhere on the body. The term folliculitis barbae is inflammation of hair follicles in the beard area (‘barba’ is the Latin word for beard).  

• Folliculitis barbae - printable version

Folliculitis decalvans is a rare chronic (long term) inflammatory condition of the scalp. Very rarely it can affect other hair-bearing skin such as the beard, armpits, pubic area and legs. The prolonged inflammation that usually occurs leads to scarring. Folliculitis decalvans is derived from Latin and means inflammation of the hair root associated with hair loss.

Folliculitis decalvans is not contagious and is not a type of skin cancer.

• Folliculitis decalvans - printable version

Fox-Fordyce disease is a rare skin disorder affecting the apocrine sweat glands. These are special sweat glands found in the armpits, genital region and breasts that produce a more dense secretion than the normal or ‘eccrine’ sweat glands found elsewhere on the body. Patients with this condition experience itchy bumps on the skin around the hair follicles. 

• Fox-Fordyce disease - printable version

Frontal fibrosing alopecia is a form of scarring hair loss affecting the hair margin on the front of the scalp. This happens due to inflammation and destruction of the hair follicles. There may also be hair loss from the scalp near the ears and from the eyebrows. Sometimes hair loss can also occur from other parts of the body, but this is less common. FFA occurs mostly in white postmenopausal women but can occur in premenopausal women, men, and people of other ethnicities. Frontal fibrosing alopecia is thought to be a variant of another condition called lichen planopilaris.

• Frontal fibrosing alopecia - printable version

Fungal infections of the nails are also known as dermatophytic onychomycosis, or tinea unguium. The responsible fungus is usually the same as that that causes athlete’s foot – a common infection of the skin of the feet, especially between the toes. In athlete’s foot the responsible fungus lives in the keratin that makes up the outer layer of the skin. When the fungus spreads to the keratin of the nails, the result is a fungal nail infection. 

• Fungal infections of the nails - printable version

Granuloma annulare is an uncommon skin condition, which most often affects children and young adults but can occur at any age. It is twice as common in women as in men. The reason for this is unknown. 

It usually presents as groups of small firm bumps in the skin which come together to form a characteristic ring shaped (annular) patch. These typically occur on only one or two sites of the body, often overlying bony areas such as the back of the hands, the feet, elbows or ankles. 

• Granuloma annulare - printable version

Guselkumab is a biologic medicine that has been designed to treat psoriasis. It works by specifically targeting a chemical messenger (known as a ‘cytokine’) in the body called ‘interleukin-23’ (IL-23). We know that IL-23 is one of the main causes of inflammation in psoriasis, and by blocking it guselkumab can improve symptoms of psoriasis. 

• Guselkumab - PRINTABLE VERSION

A ‘haemangioma’ (Greek for blood-vessel-growth) of Infancy is a benign (not cancerous) overgrowth of blood vessel cells that is self-limiting (will stop growing without treatment). The term ‘strawberry naevus’ or ‘strawberry haemangioma’ is used for a haemangioma that look similar to a strawberry.

• Haemangioma of infancy - printable version

Hailey-Hailey disease is also known as familial benign chronic pemphigus. It was originally described by the Hailey brothers. It is a rare inherited skin condition in which there are red scaly areas that can be itchy and sore, that can lead to superficial blisters and eroded (broken) areas of the skin. This usually affects the folds of the groin, armpits, neck and under the breasts. The condition flares intermittently and tends to come and go. Many patients are able to lead full and normal lives, with their condition being a nuisance rather than a serious problem. Some people are more severely affected and experience more persistent painful raw areas of the skin with development of superficial blisters.

• Hailey-Hailey disease - printable version

Female pattern hair loss (FPHL) has also been called androgenetic alopecia. It is the most common type of alopecia (hair loss) in women and the severity can vary.

• Hair loss - female pattern - printable version

Male pattern hair loss (MPHL) is the most common type of hair loss in men. It is also known as androgenetic alopecia. It affects about 50% of men over the age of 50.

• Hair loss - male pattern - printable version

Hand dermatitis is also called hand eczema. It is common and can affect about one in every 20 people. It can start in childhood as part of an in-built tendency to eczema, but is commonest in teenagers and adults. Hand dermatitis may be a short-lived, transient problem. However, in some people, it lasts for years and can have a great impact on daily life.

• Hand dermatitis - printable version

Head lice are very common. They are small (adult lice are the size of a sesame seed) grey-brown insects. They cannot fly or jump; neither can they burrow into the scalp. They can affect anyone, with long or short hair, no matter how clean the hair is.

• Head lice - printable version

There are two herpes simplex viruses that cause skin infection. They are called herpes simplex type 1 and type 2. They can be transferred from person to person by direct skin to skin contact with the affected place when enough virus is present. This is often a lesion or sore but transmission may also occur at other times, perhaps when there is only an itch or tingle in the area. The most common places of infection are the mouth (known as ‘cold sores’), followed by the genital area (genital herpes) and the hands. Most people are only infected in one area and are unlikely to transfer the infection to other parts of their bodies. 

Infection may be followed by symptoms, such as sores or blisters, within a few days but some people will not notice anything for months or years. Others are carriers who never have symptoms. The virus remains dormant in the sensory nerves close to the place of original infection.

Reactivation may result in more blisters nearby, on skin that is served by the same nerves (dermatome). The frequency of recurrences varies from person to person. For some people symptoms appear several times a year, in others rarely or never.

• Herpes simplex - printable version

Hidradenitis suppurativa is a long term, recurrent, and painful disease in which there is inflammation (redness, tenderness and swelling) in areas of skin containing apocrine sweat glands. These glands are found mainly in the armpits, breasts and groins. Within HS there is a blockage of the hair follicles. This causes a mixture of boil-like lumps, areas leaking pus, and scarring.Hidradenitis suppurativa is a long term, recurrent, and painful disease in which there is inflammation (redness, tenderness and swelling) in areas of skin containing apocrine sweat glands. These glands are found mainly in the armpits, breasts and groins. Within HS there is a blockage of the hair follicles. This causes a mixture of boil-like lumps, areas leaking pus, and scarring.

Hidradenitis suppurativa tends to begin around puberty age, and is more common in women. It is estimated to affect about 1% of the population.

• Hidradenitis suppurativa - printable version

Hirsutism refers to excessive growth of dark, thick and coarse hair in an individual (usually female) in a male pattern. Commonly affected areas are upper lips, chin, central chest, midline of the stomach, lower back, buttocks and front of thighs. Hirsutism affects approximately 10% of women in Western societies and is commoner in those of Mediterranean or Middle-Eastern descent.

If the excessive hair is generalised and not in a gender specific pattern, the term is ‘hypertrichosis’, which means increased (‘hyper’) hair (‘trichosis’). In this leaflet we will only discuss hirsutism.  

• Hirsutism - printable version

Our hands come into daily contact with many substances such as household detergents and cleaning products; personal cleansers including soaps, shampoos and wet wipes; food components such as fruit acids and plant chemicals and water.These can take away the protective oils that keep the skin moist, leading to chapping, dryness, and irritation. Frequent contact with water is one of the commonest causes of skin irritation. Once the skin on the hands is irritated and damaged, it is prone to further damage and a vicious circle is set up leading to hand dermatitis, or making existing dermatitis worse. Dermatitis in this leaflet refers to any rash that affects the skin including eczema, psoriasis, allergic contact or irritant contact dermatitis.

• How to care for your hands - printable version

The Lymphatic System

Lymph nodes (‘glands’) are part of the lymphatic system, which is a network of tiny tubes that carry a colourless fluid called lymph through the skin and deeper parts of the body. Lymph fluid contains immune cells (lymphocytes), nutrients and waste materials.

 Lymphatic Vessels

Lymph fluid bathes the cells of the skin and internal organs. It drains into lymphatic vessels then larger lymphatic vessels called ducts in the neck before joining the blood stream near the heart (see Figure 1).

Lymph Nodes

Lymph nodes (‘glands’) are small ‘bean-shaped’ nodules that contain millions of infection fighting lymphocyte cells. They are found at intervals along the lymphatic vessels like ‘beads on a string’. The lymph nodes filter out harmful organisms and abnormal cells before the lymph reaches the blood stream.

Lymph nodes can only be felt in certain areas of the body (see Figure 1):

• head and neck
• axilla (armpit)
• inguinal area (groin)
• back of knees

Lymph nodes are usually too small to feel. However, sometimes they can be felt in slim people as smooth pea-sized lumps, usually in the groin. Another time when they can be felt is when you have an infection, (for example, a sore throat or an ear infection which can make the neck lymph nodes enlarged, painful and tender as these are the nearest lymph nodes to the site of infection).

Lymph nodes can also become enlarged if cancer cells lodge in them. In this case, they are usually painless.

• How to check your lymph nodes - printable version

Hydroa vacciniforme is an extremely rare skin condition in which there is an abnormal sensitivity of the skin to sunlight (photosensitivity). It is neither infectious nor dangerous, but it can restrict an affected person’s lifestyle, particularly during the summer months and on holidays.

The term hydroa is possibly from the Greek for ‘watery eggs’, a reference to the blisters that characterise this condition; vacciniforme derives from the Greek for the ‘pox-like’ permanent scars (resembling large deep chicken pox scars) that result when the blisters heal.

Hydroa vacciniforme usually affects children aged 3-15 years, and is more common in females than males. In boys, hydroa vacciniforme may develop at a later age than in girls, and go on for longer.

• Hydroa vacciniforme - printable version

Hydroxycarbamide, formerly known as hydroxyurea, affects cells that are dividing rapidly, such as the skin cells in psoriatic plaques and the blood cells in the bone marrow. It is mainly used for cervical and blood cancers, but is also used to treat psoriasis. It is known as a ‘cytotoxic’ medicine, meaning that it interferes with cell growth. 

• Hydroxycarbamide - printable version

Hydroxychloroquine is one of several antimalarial drugs that have anti-inflammatory effects useful in other diseases.

Hydroxychloroquine is particularly effective for systemic lupus erythematosus (SLE) and discoid lupus erythematosus (DLE). By reducing inflammation, hydroxychloroquine can decrease pain, swelling and stiffness of joints, and improve or clear some rashes.

• Hydroxychloroquine - printable version

Hyperhidrosis means excessive sweating. It can be localised or affect the whole face and body.

Sweating is controlled by the brain, which sends signals along nerves called “sympathetic nerves” to the small sweat glands in the skin. These nerves are part of the “autonomic nervous system” which controls many unconscious body functions.

Increased sweating is a normal response to a rise in body temperature, and to emotions such as anxiety.

A treatment which reduces sweating is called an antiperspirant. This is different from a deodorant, which reduces odour, usually through an antibacterial effect. The two are often combined in the same product.

• Hyperhidrosis - printable version

Ichthyosis is the term used to describe continual and widespread scaling of the skin. It may be inherited (genetic) or acquired during life. The inherited forms are rare, generally present from infancy, and are usually lifelong conditions. Acquired ichthyosis can develop at any age due to a number of medical problems, such as kidney disease.

The commoner forms of inherited ichthyosis are mild and do improve during warmer weather. There are a number of very rare conditions where ichthyosis occurs with problems in other systems of the body. Each of the major types of ichthyosis will be discussed briefly, followed by an outline of the management.

• Ichthyosis - printable version

Imiquimod is a cream that when applied to the skin activates the immune system to recognise abnormal cells and causes inflammation which removes them.

In the UK, two strengths of Imiquimod cream are available, a 5% cream (trade name Aldara®) and a 3.75% cream (Zyclara ®).

• Imiquimod cream - printable version

This leaflet has been written to give you information aboutimmunisations (vaccinations), which may affect you when you are taking medicines that act by suppressing the immune system. This includes information about vaccinations which are:

1.    Recommended before you start immune suppressing medicines

2.    Safe for you to have while you are taking this treatment

3.    Need to be avoided 

• Immunisation - printable version

Impetigo is a bacterial infection of the surface of the skin. In the UK, it is the most common skin infection seen in young children, but may be seen in people of any age. 

• Impetigo - printable version

Infliximab is a powerful anti-inflammatory drug that has been designed to resemble normal human molecules, and is therefore classed as a “biological” treatment. It reduces inflammation by inhibiting the activity of a chemical (“cytokine”) in the body called ‘tumour necrosis factor alpha’ (TNF-alpha).

• Infliximab - printable version

This is a procedure involving the injection of a steroid solution directly into the skin lesion or immediately below the skin, with the aim of improving its appearance and/or reducing symptoms such as itch or pain. The steroid preparation most frequently used in this procedure is called triamcinolone acetonide, and is sometimes referred to as “intralesional triamcinolone”.

• Intralesional steroid therapy - printable version

Iontophoresis (pronounced eye-on-toe-for-ree-sis) is a safe and effective treatment that can be used to reduce excessive sweating (hyperhidrosis) of the hands, feet, underarms and face (if the necessary attachment is available to go onto the machine).

• Iontophoresis for hyperhidrosis - printable version

Isotretinoin (brand name Roaccutane) belongs to a group of drugs called retinoids, which are closely related to vitamin A. It works in a variety of ways, targeting different factors that cause acne including the production of sebum (an oily substance produced by the skin) and the production of keratin (outer scales of skin) that block the pores of the hair follicle.

• Isotretinoin - printable version

Ixekizumab is a biologic medicine that has been designed to treat psoriasis. It works by specifically targeting a chemical messenger (known as a ‘cytokine’) in the body called ‘interleukin-17A’ (IL-17A). We know that IL-17A is one of the main causes of inflammation in psoriasis and psoriatic arthritis, and by blocking it ixekizumab can improve symptoms of these conditions. 

• Ixekizumab

Junctional epidermolysis bullosa (JEB) is a rare inherited (genetic) skin disorder. It is not an infection, it is not contagious and it is not due to an allergy. It is different from the other forms of epidermolysis bullosa (EB), which include epidermolysis bullosa simplex, dystrophic epidermolysis bullosa and Kindler Syndrome. Individuals who have JEB will not develop one of the other types of epidermolysis bullosa at a later date.

The skin of those who have JEB is fragile and minor everyday knocks and friction, such as rubbing or scratching, cause blisters or raw areas. There are three main sub-types of JEB: severe, or Herlitz, JEB; intermediate, or non-Herlitz, JEB and JEB with pyloric atresia. JEB varies in severity, from relatively mild with a normal lifespan, to the most severe form in which babies may not live beyond their first birthday.

• Junctional epidermolysis bullosa - printable version

JXG is a skin lump caused by an excess of cells known as histiocytes. It is rare and occurs mainly in infants and young children, although about 10% occur in adults. It is not known what causes this condition. It is not a type of cancer. 

• Juvenile xanthogranuloma - printable version

Kaposi’s sarcoma is a growth of the cells lining lymphatic vessels, caused by a virus in people with a weakened immune system. The virus is called human Herpes virus type 8 (Kaposi sarcoma herpes virus, HHV8). A common cause of the weakened immune system is HIV infection. It is named after Dr Moritz Kaposi, a Hungarian dermatologist, who first described it in 1872. ‘Sarcoma’ (from ancient Greek ‘flesh’) means a cancerous growth starting from abnormal cells of connective tissue.

Kaposi’s sarcoma can be limited, only affecting the skin, or more extensive with involvement of lymph nodes and internal organs such as the lungs or digestive system. It may be chronic which means it slowly gets worse, or it may rapidly worsen.

• Kaposi's sarcoma - printable version

When a wound heals, it leaves a scar. A keloid (also called a keloid scar) is the name given to a scar that overgrows and becomes larger than the original wound. It is not uncommon for a scar to become slightly thick and raised. This is called a hypertrophic scar. Unlike hypertrophic scars, keloids:

• Can develop after very minor skin damage, such as an acne spot, or sometimes without any obvious trauma to the skin (spontaneous keloids).
• Spread beyond the original area of skin damage.
• May be permanent.

• Keloids - printable version

KA is a relatively common, rapidly growing skin growth that usually develops on sun-exposed skin. It starts in skin cells that surround the hair follicle. Early diagnosis is needed to differentiate a keratoacanthoma from a skin cancer called squamous cell carcinoma (SCC). However, unlike an SCC, a keratoacanthoma is benign.  

• Keratoacanthoma - printable version

Keratosis pilaris (KP) is a very common and may be present in half the population. It is a completely harmless skin condition. It affects 50-70% of adolescents and approximately 40% of adults. Its name gives some idea of what it is; ‘keratosis’ means that there is too much keratin, which makes up the tough horny outer layer of the skin, while ‘pilaris’ comes from the Latin for hair (pilus). In keratosis pilaris, many small (1 to 2 mm across) horny plugs can be seen blocking the hair follicles on the upper and outer parts of the arms and thighs. This can look like goose bumps but feels slightly rough. Keratosis pilaris appears when extra keratin accumulates in the hair follicles. This usually starts in childhood and becomes more obvious during adolescence and in adulthood. For reasons not fully understood the condition seems to be better in the summer than in the winter perhaps because in winter the skin often gets dry while in summer the sweat makes it less dry. Keratosis pilaris may be associated with ichthyosis vulgaris and atopic eczema, however this may be coincidental.

• Keratosis pilaris - printable version

Latex is a milky sap from plants like the tropical rubber tree. It contains a mixture of water, sugar and proteins. The sap is collected by drilling into the tree and used to make rubber items such as household gloves and medical gloves, shoes, tyres, balloons and condoms. During the manufacturing process chemicals such as accelerators are added to harden it and the rubber item is heated then finally rinsed.  The finished item, in addition to latex, may contain residual added (non-latex) proteins and chemicals and these can also cause allergic reactions.     

• Latex Allergy

Lentigo maligna is one type of the earliest stage of a skin cancer called melanoma.

The word ‘melanoma’ comes from the Greek word ‘melas’, meaning black. Melanin is the dark pigment that gives the skin its natural colour and is made in the skin by pigment cells called melanocytes. After our skin is exposed to sunlight, the melanocytes make more melanin, and so the skin becomes darker.

Melanocytes may grow together in harmless groups or clusters, which are known as moles. Most people have between 10 and 50 moles and often they are darker than the surrounding skin.

Melanomas can arise in or near to a mole, but can also appear on skin that looks quite normal. They develop when the skin pigment cells (melanocytes) become cancerous and multiply in an uncontrolled way. They can then invade the skin around them and may also spread to other areas such as the lymph nodes, liver and lungs.

Lentigo maligna is a type of melanoma called ‘in situ’ melanoma. ‘In situ’ means that the cancer cells have not had the opportunity to spread anywhere else in the body. There are cancer cells in the top layer of the skin (the epidermis) but they are all contained in the area in which they began to develop. They have not started to spread or grow (‘invade’) into deeper layers of theskin. This is why some doctors call in situ cancers ‘pre-cancer’.

Lentigo maligna is a slow growing condition which can take years to develop. It appears in skin that has had a lot of sun exposure, usually the face, neck or upper arms.

Lentigo maligna can be cured with surgery. However, if the whole area is not removed completely with the appropriate surgery, some may develop into an invasive melanoma. It is therefore important to have it removed with a rim of normal skin (an adequate surgical margin). There are also preventative measures which can be taken (see below) that will further lower the risk of recurrence in the future.

• Lentigo maligna - printable version

Lichen planopilaris is a type of scarring hair loss that occurs when a relatively common skin disease, known as lichen planus, affects areas of skin where there is hair. Lichen planopilaris destroys the hair follicle and then replaces it with scarring, resulting in permanent hair loss. Lichen planopilaris can be divided into three different subtypes (see below). It is between 2 and 5 times more common in women than it is in men with the commonest age of onset being in the mid-40s.

• Lichen planopilaris - printable version

In dermatology, the word ‘lichen’ means small bumps on the skin and ‘planus’ means ‘flat’, so the name comes from a description of the rash’s appearance. Lichen planusis a fairly common (0.2-1% of the population worldwide), itchy, non-contagious rash that usually occurs in adults between the ages of 40 to 60. It is rare in children. It affects all ethnicities equally; however oral disease affecting the lips and inside the mouth, may be more common in patients from the Indian subcontinent originally.

• Lichen planus - printable version

Lichen sclerosus is a chronic inflammatory skin condition which can affect any part of the skin, but it most often affects the genital skin (vulva) and the skin around the anus. It can start in childhood - or adulthood (usually after the menopause) and affect girls or women of any age.

• Lichen sclerosus (female) - printable version

Lichen sclerosus is a chronic inflammatory skin condition which can affect any part of the skin, but in men is most often seen on the foreskin and tip of the penis. It can affect boys or men of any age.

In some people, lichen sclerosus also affects the skin elsewhere on the body, where it can cause whitish patches of skin, but usually no discomfort.

• Lichen sclerosus (male) - printable version

Lichen sclerosus is an inflammatory skin condition. It mainly tends to affect the genital areas (vulva and penis). The cause is not known, but it may be a form of autoimmune disease (when the immune system attacks healthy cells in the body by mistake) and can run in families.

• Lichen sclerosus in female children

The term ‘lichen’ is Latin and means a plant-like moss covering trees. Lichen simplex describes a response to the skin being repeatedly scratched or rubbed over a long period of time (also called lichen simplex chronicus). A single or multiple plaque (thickened area of skin) of rough skin forms, with increased markings and sometimes little bumps around the hair follicles.

Lichen simplex can affect any age group, but is most common in adults and is unusual in children.

• Lichen simplex - printable version

Linear IgA disease is a very rare blistering condition of the skin in adults. A similar condition affecting children is known as Chronic Bullous Disease of Childhood (CBDC).

The condition is called ‘Linear IgA disease’ because a type of protein called  immunoglobulin A (IgA) can be seen deposited under the outer layer of the skin (the epidermis) in a line (linear) when a small sample of skin biopsy is prepared specially and examined under the microscope. 

• Linear IgA disease - printable version

Lymphoedema is a long-term swelling that develops because of a fault within the lymphatic drainage system. This may be as a result of the lymphatic system not developing properly, or because it has been damaged.

• Lymphoedema - printable version

Melanocytic naevi are pigmented moles. The word ‘melanocytic’ means that they are made up of the cells (melanocytes) which produce the dark pigment (melanin) that gives the skin its colour. Melanocytes clustered together form naevi. This type of moles vary in colour in different skin tones and they are easier to see on pink skins.

Some moles are present at birth or appear within first two years of life are known as congenital melanocytic naevi. Most develop during childhood and early adult life and are consequently called acquired melanocytic naevi. The number of moles increase up to the age of 30-40. Thereafter, the number of naevi tend to decrease. New moles appearing in adulthood need to be monitored and checked if growing or changing. Moles can be found anywhere on the skin, including on the hands and feet, genitals, eyes and scalp.

• Melanocytic naevi - printable version

Melanoma is a type of skin cancer, which arises from the pigment cells (melanocytes) in the skin. One of the main causes of melanoma is exposure to too much ultraviolet light in sunlight. The use of artificial sources of ultraviolet light, such as sunbeds, also increases the risk of getting a melanoma.

Melanocytes make a brown/black pigment (known as melanin), and often the first sign of a melanoma developing is a previous mole changing in colour or a new brown/black lesion developing on the skin. Most frequently there is darkening in colour but occasionally there is loss of pigmentation with pale areas or red areas developing. Occasionally melanomas have no pigment and appear just a pink/red colour. The development of this melanoma on the skin is known as the primary melanoma.

Melanoma is considered to be the most serious type of skin cancer. This is because it is more likely to spread (metastasise) from the skin to other parts of the body than other types of skin cancer. If melanoma has spread to other parts of the body, those deposits are known as secondary melanoma (secondaries/metastases). Although a diagnosis of melanoma can be serious, most melanomas are diagnosed at an early stage and so do not cause any further problem. If lesions are not removed caught at the early stages then there is a higher risk of the melanoma spreading, which can reduce life expectancy.

• Melanoma stage 1 - printable version

Melanoma is a type of skin cancer, which arises from the pigment cells (melanocytes) in the skin. One of the most important causes of melanoma is exposure to too much ultraviolet light in sunlight. The use of artificial sources of ultraviolet light, such as sunbeds, also increases the risk of getting a melanoma.

Melanoma is considered to be the most serious type of skin cancer because it is more likely to spread (metastasise) from the skin to other parts of the body than other types of skin cancer. If melanoma has spread to other parts of the body, those deposits are known as secondary melanoma (secondaries/metastases). Although a diagnosis of melanoma can be serious, most melanomas are diagnosed at an early stage and so do not cause any further problem. If lesions are not removed at the early stages then there is a higher risk of the melanoma spreading, which can reduce life expectancy.

• Melanoma - Stage 1B printable version

Melanoma is a type of skin cancer, which arises from the pigment cells (melanocytes) in the skin. One of the most important causes of melanoma is exposure to too much ultraviolet light in sunlight. The use of artificial sources of ultraviolet light, such as sunbeds, also increases the risk of getting a melanoma.

Melanocytes make a brown/black pigment (known as melanin), and often the first sign of a melanoma developing is a previous mole changing in colour or a new brown/black lesion developing on the skin. Most frequently there is darkening in colour but occasionally there is loss of pigmentation with pale areas or red areas developing. Occasionally melanomas have no pigment and appear just a pink/red colour. The development of this melanoma on the skin is known as the primary melanoma.

Melanoma is considered to be the most serious type of skin cancer because it is more likely to spread (metastasise) from the skin to other parts of the body than other types of skin cancer. If melanoma has spread to other parts of the body, those deposits are known as secondary melanoma (secondaries/metastases). Although a diagnosis of melanoma can be serious, most melanomas are caught at an early stage and so do not cause any further problem. If lesions are not caught at the early stages then there is a higher risk of the melanoma spreading, which can reduce life expectancy.

• Melanoma stage 2 - printable version

Melanoma is a type of skin cancer, which arises from the pigment cells (melanocytes) in the skin. One of the most important causes of melanoma is exposure to too much ultraviolet light in sunlight. The use of artificial sources of ultraviolet light, such as sunbeds, also increases the risk of getting a melanoma.

Melanocytes make a brown/black pigment (known as melanin), and often the first sign of a melanoma developing is a previous mole changing in colour or a new brown/black lesion developing on the skin. Most frequently there is darkening in colour but occasionally there is loss of pigmentation with pale areas or red areas developing. Occasionally melanomas have no pigment and appear just a pink/red colour. The development of this melanoma on the skin is known as the primary melanoma.

Melanoma is considered to be the most serious type of skin cancer because it is more likely to spread (metastasise) from the skin to other parts of the body than other types of skin cancer. If melanoma has spread to other parts of the body, those deposits are known as secondary melanoma (secondaries/metastases).

• Melanoma stage 3 - printable version

Melanoma is a type of skin cancer, which arises from the pigment cells (melanocytes) in the skin. One of the most important causes of melanoma is exposure to too much ultraviolet light in sunlight. The use of artificial sources of ultraviolet light, such as sunbeds, also increases the risk of getting a melanoma.

Melanocytes make a brown/black pigment (known as melanin), and often the first sign of a melanoma developing is a previous mole changing in colour or a new brown/black lesion developing on the skin. Most frequently there is darkening in colour but occasionally there is loss of pigmentation with pale areas or red areas developing. Occasionally melanomas have no pigment and appear just a pink/red colour. The development of this melanoma on the skin is known as the primary melanoma.

Melanoma is considered to be the most serious type of skin cancer because it is more likely to spread (metastasise) from the skin to other parts of the body than other types of skin cancer. If melanoma has spread to other parts of the body, those deposits are known as secondary melanoma (secondaries/metastases). 

• Melanoma stage 4 - printable version

Melanoma in situ is the very earliest stage of a skin cancer called melanoma. ‘In situ’ is Latin for ‘in space’. It means that the cancer cells have not had the opportunity to spread to anywhere else in the body.

About 7,000 people in the UK are diagnosed with melanoma each year. The word ‘melanoma’ comes from the Greek word ‘melas’, meaning black. Melanin is the pigment that gives the skin its natural colour. Melanin is made in the skin by pigment cells called melanocytes. After our skin is exposed to sunlight, the melanocytes make more melanin, and so the skin becomes darker.

Melanocytes sometimes grow together in harmless groups or clusters, which are known as moles. Most people have between 10 and 50 moles and often they are darker than the surrounding skin.

Melanomas can arise in or near to a mole but can also appear on skin that looks normal. They develop when the skin pigment cells (melanocytes) become cancerous and multiply in an uncontrolled way. They can then invade the skin around them and may also spread to other areas such as the lymph nodes, liver and lungs.

In melanoma in situ, cancer cells are confined to the top layer of the skin (the epidermis) and are all contained in the area in which they began to develop. They have not started to spread or grow into deeper layers of the skin and have not become invasive. The outlook is excellent.This is because there are no blood or lymphatic channels in the top layer of the skin via which the abnormal cells can spread.  Some doctors call in situ cancers ‘pre-cancer’.

Melanoma in situcan be cured if it is cut out (excised) completely. However, if not removed with appropriate surgery, it can develop into an invasive cancer. This is why it is important to have melanoma in situ removed with a small rim of normal skin (an adequate surgical margin) and to know about preventative measures you can take which will lower your risk of another melanoma in the future.

• Melanoma in situ - printable version

Melasma, also called ‘chloasma’ and ‘pregnancy mask’, is a common skin condition of adults in which brown or greyish patches of pigmentation (colour) develop, usually on the face. The name comes from melas, the Greek word for black, or cholas, from the word green-ish. It is more common in women, particularly during pregnancy (when up to 50% of women may be affected). Sometimes men may also be affected. Melasma is more common in people of colour and those who tan very quickly but can occur to anyone.

Melasma usually becomes more noticeable in the summer and improves during the winter months.It is not an infection; therefore, it is not contagious, and it is not due to an allergy. It is not cancerous and will not develop into skin cancer.

• Melasma - printable version

Mepacrine was originally introduced as a treatment for malaria and for certain other tropical infections. It is an unlicensed medication in the United Kingdom. It is one of several antimalarial drugs that have also been found to have anti-inflammatory properties, which can help some skin conditions.

• Mepacrine - printable version

Methotrexate is a type of medicine called an immunosuppressant. This means it suppresses the body’s immune system and lowers immunity. The immune system is important in fighting infections, but sometimes immune system cells mistakenly attack the body’s own healthy tissues, triggering long-term inflammation. Methotrexate reduces the inflammation caused by your condition by dampening down the activity of these cells in the immune system. 

• Methotrexate - printable version

Mohs micrographic surgery is a specialised surgical method for removing certain types of skin cancer. It was first developed by Dr Frederic Mohs in the 1930s.

Traditionally, operations for treating skin cancer surgically have involved removal of the area affected by the skin cancer together with an area of healthy unaffected skin around and below the skin cancer in order to ensure that the entire cancer has been completely removed with suitable margins of excision. Once removed, the skin is sent to the laboratory for examination by a pathologist (a doctor who specialises in medical diagnosis by looking at the cells with a microscope) to confirm whether the operation has been successful or not. It usually takes about 2 weeks for pathology report to become available. If the report shows that the skin cancer has not been fully removed, a further procedure may be necessary.

During the procedure of Mohs micrographic surgery, the skin cancer is removed a thin layer at a time with a small margin of healthy skin surrounding it. Each layer is immediately checked under the microscope by either the surgeon or a pathologist. The layer of skin is examined in horizontal sections. A further layer is taken from any areas in which the tumour remains until all of the skin cancer has been fully removed. The advantage of removing the skin layer by layer in this way is that as little healthy skin around the skin cancer is removed, which keeps the wound as small as possible. Secondly, your dermatological surgeon can be almost certain that the skin cancer is fully removed on the day of the procedure. 

• Mohs surgery - printable version

Molluscum contagiosum is caused by a pox virus. It can spread to others if the spots are in direct contact with someone else or they share the same item such as a towel. The spots usually appear a few weeks later. They are more common and extensive in people who have eczema. Sometimes people whose immune system is suppressed for any reason, such as by HIV infection or through taking immunosuppressive treatments may develop large numbers of molluscum spots, but most people with molluscum contagiosum are generally in good health.

• Molluscum contagiosum - printable version

Morphoea is a rare skin disorder where areas of skin become much thicker and firmer than normal. It is sometimes called ‘localised scleroderma.’ This term originates from two words ‘sklero’ meaning ‘hard’ and ‘derma’ meaning skin. It should not be confused with systemic sclerosis, which is a different disease that affects internal organs and the blood circulation as well as the skin. Morphoea usually affects a few small areas of the skin. Very rarely, it can occur over larger areas of the body in a form called ‘generalised morphoea.’ 

• Morphoea and localised scleroderma - printable version

MMP is the most up-to-date term for this condition. Other names include cicatricial pemphigoid, oral pemphigoid and ocular pemphigoid.

MMP is an uncommon blistering condition which most frequently affects the lining of the mouth and gums. Other moist surfaces of the body (known as mucous membranes) can also be affected, and these include the surface layers of the eyes, the inside of the nose, the throat and the genitalia. The skin is sometimes affected by a few scattered blisters. MMP usually starts in middle and old age. Although it is not usually a serious condition in the mouth, the diagnosis of any type of MMP is important as it will alert your specialist to the possibility that the condition may involve your eyes, even if you have no symptoms. Eye involvement (known as ocular cicatricial pemphigoid or ocular MMP) does not occur in all people with MMP, but is potentially serious as it may cause scarring and affect your eyesight.  Scarring may also affect the throat and the genitalia, and may be very serious if the larynx is affected.

• Mucous membrane pemphigoid - printable version

Mycophenolate mofetil (MMF) is a medicine that is mainly used to stop the body from rejecting a transplanted organ (e.g. kidney, heart and liver). MMF can also be used to treat skin conditions. It reduces the action of the body’s own defence system (the immune system) and is one of a group of drugs known as immunosuppressive agents. It is used in certain skin conditions in which the immune system loses control and begins to act against the body. 

• Mycophenolate mofetil - printable version

Mycosis fungoides is a type of cutaneous or skin lymphoma. It is the commonest of a group of conditions known as cutaneous T-cell lymphomas. Cutaneous T-cell lymphomas are cancers that affect the skin and are caused by uncontrolled growth of the T-cell lymphocytes in the skin. T cell lymphocytes are white blood cells that can be found all over the body and in the blood stream.

Mycosis fungoides is a rare condition. Each year in the UK, approximately 450 people are newly diagnosed with mycosis fungoides. Most affected people live a normal life span.  

Mycosis fungoides can occur at any age but it most often starts between the ages of 50 and 70 years.

• Mycosis fungoides - printable version

Necrobiosis lipoidica is an uncommon inflammatory condition in which shiny, reddish-brown or yellowish patches develop in the skin, usually in young adults and early middle age. The condition is most commonly seen in conjunction with diabetes - both the insulin-dependent type 1 and non-insulin-dependent type 2, but it can also occur in non-diabetic people as well.

• Necrobiosis lipoidica - printable version

Nicotinamide is a form of vitamin B3. It can be taken as tablets to prevent and treat niacin deficiency (pellagra). Nicotinamide has protective effects against skin damage caused by ultraviolet (UV) radiation.

• Nicotinamide - printable version

‘Pruritus’ is the word doctors often use for itching. ‘Prurigo’ is a related word, which describes the changes that appear in the skin after it has been itched and scratched for a long time. In nodular prurigo these changes look like firm very itchy bumps (nodules) on the skin’s surface. These can improve or resolve when the person stops scratching the area, although for many people this can be very difficult without proper and sometimes prolonged medical treatment.

• Nodular prurigo - printable version

Omalizumab is a drug that has been specially designed to mimic normal human molecules, and for this reason is classified as a biologic drug. It interferes with natural antibodies called IgEs in the body and prevents them from causing histamine release from certain cells.

• Omalizumab

Lichen planus is an inflammatory condition of the skin but can also affect the mouth (oral lichen planus). Oral lichen planus may occur on its own or in combination with lichen planus of the skin, nails or genitals. It is thought to affect 1 to 2% per cent of the population, and typically affects women after the age of 40 years. Oral lichen planus can occur in men, but children are rarely affected.

• Oral lichen planus - printable version

Oral treatment with corticosteroids is also known as ‘oral cortisone therapy’ or ‘systemic steroid therapy’. The word ‘oral’ means that the steroids are taken by mouth, usually in tablet or liquid form.

Corticosteroids (also known as steroids) are chemicals (hormones) that occur naturally in the body. They have numerous roles in the body which include decreasing inflammation and suppressing the body's immune system. Corticosteroid medicines are man-made but are similar to these natural hormones. Corticosteroids are produced in the cortex (outer layer) of the adrenal glands (hence the ‘cortico-’ part of the name).

The corticosteroids used most often in medical treatment, prednisolone and dexamethasone, are not exactly the same as the ones produced in the body. It is convenient to refer to them just as ‘corticosteroids’ or 'steroids', but you should be aware that they are different from the type of steroids (anabolic steroids) used for body building.        

• Oral treatment with corticosteroids - printable version

Palmoplantar (palmo meaning palm of the hand, plantar meaning sole of the foot) pustulosis is a persistent (chronic) condition which causes blisters filled with fluid on the palms and the soles of the feet. It can sometimes occur with the skin condition psoriasis. 

• Palmoplantar pustulosis - printable version

Patch testing is a specialist procedure carried out in dermatology departments to find out whether your skin condition is caused or made worse by an allergy to substances which have come into contact with your skin. This is called contact allergy. Substances that cause an allergic reaction are called allergens. They may be found both at home and at work.

• Patch testing - printable version

Pemphigoid is a rare blistering disorder, which usually occurs in later life, the average age of onset being over 70 years. The blisters come up on the skin and, less often, in the mouth too. This is in contrast to a related condition known as ‘mucous membrane pemphigoid’ in which the brunt of the trouble is borne by the moist surfaces of the body (the mucous membranes) such as the eyes, inside the nose and mouth, and the genitals.

• Pemphigoid - printable version

Pemphigoid gestationis is a rare skin blistering disorder that is associated with pregnancy. It usually presents in mid to late pregnancy (between the 13th and 40th week of pregnancy, known as the second and third trimesters) with an itchy rash that develops into blisters. It may recur in subsequent pregnancies and occasionally recurs in women who go on to take oral contraceptive therapy or during menstruation when their periods restart after pregnancy.

It was previously known as herpes gestationis but this name has been changed as there is no association with herpes virus (cold sore) infection and unlike herpes, pemphigoid gestationis does not spread from person to person.

• Pemphigoid gestationis - printable version

Pemphigus vulgaris is a rare autoimmune skin disease and affects around 3 people per 100,000 population. Pemphigus vulgaris may cause severe blistering of the skin and the mucous membranes lining the mouth, nose, throat, eyes and genital area. Blisters develop in the upper layer of the skin and have a thin and fragile outer surface that breaks away easily leaving raw areas (erosions) that can be extensive and painful. 

• Pemphigus vulgaris - printable version

Peri-oral dermatitis is a common skin condition that more commonly affects women aged 20 to 50 years old. It usually causes persistent redness or small bumps (papules) and sometimes pus containing spots (pustules). It can persist for a few months until the cause is identified and corrected.

The name of the condition ‘Peri-oral dermatitis’can be confusing, as it is not thought to be a form of dermatitis (eczema). Instead, peri-oral dermatitis is thought to be a type of rosacea. Rosacea is a common longstanding condition that causes persistent redness, bumps and pus containing spots (pustules) on the forehead, cheeks, nose and chin. For peri-oral dermatitis, ‘steroid-provoked rosacea’might be a better name, but most people still use the name “peri-oral dermatitis”.

• Peri-oral dermatitis

Photodynamic therapy (PDT) is a technique thatis used to treat certain types of skin cancers such as superficial Basal cell carcinoma and areas of sun-damaged skin (pre-cancerous) that might become cancer in the future. In PDT, a cream is first applied to the area to be treated.  A special light or daylight then activates a cream. This treatment kills the abnormal cells in the skin.

• Photodynamic therapy - printable version

The term phototherapy is a form of treatment where fluorescent light bulbs are used to treat skin conditions. Natural sunlight has been known to be beneficial in certain skin disorders for thousands of years, and it is the ultraviolet part of the radiation produced by the sun that is used in phototherapy, in particular the ultraviolet A (UVA) and ultraviolet B (UVB) wavelengths of light.

We have produced four leaflets which focus on different types of phototherapy.

Narrowband UVB (NB-UVB) is a particular treatment where a small part of the UVB light spectrum is used to treat the skin condition. Treatment lamps produce these special rays, which has anti-inflammatory effects on the skin. Although these rays are also present in natural sunlight, UVB treatment is usually more effective than sunlight because harmful and ineffective sunlight rays are filtered out. In this way we also seek to minimise the risk of burning episodes.

• NB-UVB Phototherapy - printable version

Oral PUVA therapy is a treatment in which a medication called psoralen (P) is taken by mouth 2-3 hours before exposure of the skin to ultraviolet A (UVA) wavelengths of light. The number of tablets you will take depends on your height and weight and you will be given this medication from the hospital pharmacy. The psoralen reacts in the skin with the UVA to cause effects that help improve or clear a variety of skin conditions. The tablets also make you more sensitive to UVA in sunlight (the rays that get through cloud and window glass) on the days of your treatment.

• Oral PUVA Phototherapy - printable version

Topical PUVA therapy is a treatment in which a medication called psoralen (P) is applied to the skin before exposure of the skin to ultraviolet A (UVA) wavelengths of light. The psoralen can be applied in a variety of ways:

• Bathing the whole body in psoralen solution
• Soaking of parts of the body, for example, hands and feet, in a basin of psoralen solution
• Applying the psoralen preparation in gel form directly on the affected areas

Your doctor will discuss with you the most suitable method of treatment for you. The psoralen reacts in the skin with the UVA to help improve or clear a variety of skin conditions. It also makes you more sensitive to sunlight UVA (the rays that get through cloud and window glass) during the treatment.

• Topical PUVA Phototherapy - printable version

UVA1 means Ultraviolet A. UVA is made up of UVA1 and UVA2. UVA1 is the type of UVA which goes deepest of all into the skin.

• UVA1 Phototherapy - printable version

A pilomatricoma is a benign (non-cancerous) growth arising from the cells at the base of hair follicles. Hair follicles are specialized structures in the skin where hair grows from. Pilomatricoma has also been called a pilomatrixoma, trichomatricoma or a ‘calcifying epithelioma of Malherbe’.

• Pilomatricoma - printable version

Pityriasis alba is a common skin complaint of children and young adults. It appears as pink/pale, scaly patches which later leave pale areas on the skin. These pale areas are more noticeable in people with skin of colour, and more pronounced after exposure to the sun and the tanning of the non-affected skin. Pityriasis means skin scaling and alba means white. 

• Pityriasis alba - printable version

Pityriasis lichenoides is a rare skin disorder of unknown cause. There are two types of pityriasis lichenoides: an acute form usually found in children known as pityriasis lichenoides et varioliformis acuta (PLEVA), and a more long-lasting form known as pityriasis lichenoides chronica (PLC). 

• Pityriasis lichenoides - printable version

Pityriasis rosea is a common rash that is usually mild and lasts about 6 to 8 weeks. Its name means that the rash has a fine scale (pityriasis) and it tends to be pink (rosea).

• Pityriasis rosea - printable version

Pityriasis rubra pilaris is a rare long-terminflammatory skin condition. The name means scaling (pityriasis), redness (rubra) and involvement of the hair follicles (pilaris). It affects all races and sexes equally.

It is classified into 6 clinical types:

• Type I is the most common and is called ‘classic adult type’.
• Type II is a variation of type I, known as atypical adult onset.
• Type III, IV and V represent classical, circumscribed and atypical juvenile forms.
• Type VI is associated with HIV-associated PRP (human immunodeficiency virus infection).

• Pityriasis rubra pilaris - printable version

Pityriasis means a type of fine skin scaling, and versicolor means changing colour. It is a common and harmless rash due to the overgrowth of yeasts that live on everyone’s skin. These yeasts, called Malassezia, are not related to yeast in food or to those that cause thrush. It is also sometimes called tinea versicolor.

• Pityriasis versicolor - printable version