Pemphigus vulgaris on the skin

• When PV affects the skin, very fragile blisters form. A blister is where clear fluid collects within the skin.
  
  
  
• Because they are so fragile, PV blisters break open very easily, leaving erosions (also called lesions).
• Erosions are areas of skin or mucous membrane which have lost the top layer. They look raw and sore, like a burn. The erosions can join together to produce large areas of raw skin that look as if the top layer has been scraped off.
  
  
  
• Erosions can become dry and crusty, like scabs.
  
  
  
• When they heal, skin erosions in PV may leave discoloured marks which will usually fade. Sadly, for some people, the marks never completely go away.

Pemphigus vulgaris in the mouth

• Blisters form in the mouth in the same way as on the skin but they are almost never seen. This is because they get broken so easily. Instead, the areas where the blisters have broken (erosions) are usually seen.
  
  
  
• There may be just one or two broken blisters or there may be several broken blisters which join together.

What pemphigus vulgaris looks like under a microscope

One of the tests which is usually done if your doctor thinks you might have PV is called a biopsy (see ‘How will pemphigus vulgaris be diagnosed?’). This is where a sample of skin is taken from a blister or lesion after first making the skin numb with an injection of local anaesthetic. The sample is then looked at under a microscope, which makes it possible to see if there are any blisters in the top layer of the skin (which is called the epidermis), a feature of PV.

This picture of PV under a microscope shows blisters in the epidermis.

The epidermis is made up of several layers of skin cells arranged like a brick wall. In PV, antibodies stick to the surface of these cells. In direct immunofluorescence, the skin biopsy is processed to show up these antibodies. When viewed under a microscope, the antibodies can be seen outlining the cells like a chicken-wire fence. This is the best test for diagnosing PV (see ‘How will pemphigus vulgaris be diagnosed?’).

This picture shows the chicken-wire fence pattern of fluorescent green which shows where the antibodies have stuck to the skin cells.

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