Urticaria is a common illness affecting up to 20% of people (one in 5 people) at some point in their lives. Urticaria presents with highly itchy raised skin reactions known as weals (also known as hives) that may be round or ring-shaped, and may join together. They come and go within hours. Weals can also appear as raised lines after scratching. They can appear anywhere on the skin. Individual weals typically disappear of their own accord within 24 hours without a trace but the condition lasts longer.  Angio-oedema, swelling deep to the skin, often occurs in urticaria. Angio-oedema usually affects soft areas of skin, such as the eyelids, lips or inside the mouth but may occur anywhere. These swellings often take longer to clear and tend to be painful rather than itchy. Urticaria may present with weals alone, angio-oedema or both together.

If angio-oedema occurs without weals it may be an inherited illness called hereditary angio-oedema. This is a different problem to urticaria. It can be diagnosed with blood tests and needs different treatment.

• Urticaria and angioedema - printable version

Urticaria pigmentosa (UP) is the commonest presentation of cutaneous mastocytosis. The other three are called mastocytoma, diffuse cutaneous mastocytosis (DCM) and telangiectasia macularis eruptiva perstans (TMEP). UP and TMEP are now grouped together using the term maculopapular cutaneous mastocytosis.

Mastocytosis means too many mast cells. Mast cells are part of our immune system. They develop in the bone marrow then spread in the blood all over the body, including the skin. They release histamine if stimulated by different triggers. Urticaria pigmentosa is composed of persistent brown or red marks, made of collections of mast cells that swell and itch transiently when rubbed, similar to a hive. In the majority of cases, urticaria pigmentosa may cause skin symptoms but does not progress to more serious types of mastocytosis.

More than 75% of cases of urticaria pigmentosa start in infants and children less than 10 years old, but it can also affect older children and adults for the first time. It affects male and female patients equally.

• Urticaria pigmentosa - printable version

Ustekinumab is a drug that has been specially designed to mimic normal human molecules, and for this reason it is classed as a ‘biological’ drug. It reduces skin inflammation by blocking the activity of chemical molecules called cytokines (interleukin 12 and 23) in the body that trigger inflammation in psoriasis.

• Ustekinumab - printable version

They are marks made up of excess or abnormal blood vessels in the skin. There are many different types, and only three are described in this leaflet: salmon patches (naevus simplex); port wine stains (naevus flammeus); and strawberry naevi (infantile haemangiomas).

• Vascular birthmarks - printable version

Venous eczema is also known as varicose or stasis eczema and is the name given to a type of eczema on the lower leg. The word eczema (or dermatitis) refers to a common inflammatory skin condition. Venous eczema is more common as people get older and occurs more often in women than in men.

• Venous eczema - printable version

A venous lake is a small blood vessel (vein) in the skin, which over time has become enlarged and wider (or dilated).

• Venous lake - printable version

A venous leg ulcer is an open wound in the skin of the lower leg due to high pressure of the blood in the leg veins.

• Venous leg ulcers - printable version

Vitiligo is a persistent or chronic condition in which areas of skin lose their normal pigment and become very pale or pink. It is common, affecting about 1% of the world's population. It can start at any age after birth, but in more than half of people affected it does so before 20 years of age. The extent of the condition is unpredictable, varying from single small patches to total loss of skin colour. In most people, it tends to change slowly, with periods of stability often lasting several years. The pigment may return in some patients, but is not guaranteed, and seldom returns completely.

• Vitiligo - printable version

Vulvodynia means ongoing pain in the vulva (the female genital area) when there is nothing abnormal to see and no known cause for the pain.

Vestibulodynia is a term used for pain arising at the entrance of the vagina, in the area known as the vestibule (the area of the openings to the vagina and the urethra), when any pressure, be it touch or friction, is applied. It is also called localised vulvodynia.

Vulvodynia, whether it is generalised or localised, may be described as provoked (caused by touch) or spontaneous (occurring without touch as a trigger).

Many conditions affecting the vulva can be painful (e.g. infections such as thrush or herpes, as well as skin diseases such as eczema). In vulvodynia, pain is felt in the vulva when there is no obvious visible cause for it and other diagnoses have been ruled out by examination and investigation.

• Vulvodynia - printable version

XP is a very rare condition with about 100 patients living with it in the UK. XP can affect both sexes and all racial groups.

With XP the genetic material in the skin is unable to repair itself correctly after exposure to ultraviolet radiation (UVR), which is present in all forms of daylight and some artificial light. Without this repair mechanism working correctly a person is much more likely to develop skin cancers. XP can be divided into different types known as complementation groups A to G and Variant. There are slight clinical differences between the groups; with around 30% developing neurological problems such as hearing loss, balance problems or learning difficulties.

• Xeroderma pigmentosum - printable version

Zoon’s balanitis describes inflammation of the head of the penis (glans penis) and foreskin.  It usually affects middle-aged to elderly men who have not been circumcised.

The word balanitis is derived from the Greek word balanos, which means ‘acorn’. The ending ‘-itis’ stands for inflammation. Balanitis means inflammation of the glans penis. Zoon’s balanitis is named after Professor Zoon, a Dutch dermatologist, who described the condition in 1952.In addition to the glans penis, the foreskin is often involved.

It has also been called ‘balanitis circumscripta plasmacellularis’ because the patches are well defined, and ‘plasma cell balanitis’ because many plasma cells (a type of white blood cell) may be seen when the affected skin is examined under the microscope.

• Zoon's balanitis - printable version