Pemphigus foliaceus usually begins with small (approximately 1 cm), pruritic, crusted lesions resembling corn flakes on the upper torso and face. The crusts are easily removed, leaving chronic, superficial erosions.
Over weeks to months, the condition progresses, with an increasing number of lesions appearing on the upper torso, face, and scalp. In extensive cases, lesions develop over the entire body, become confluent, and can progress to an ‘exfoliative erythroderma’.
Pemphigus foliaceus is characterised by blistering lesions on otherwise healthy-looking skin. Blisters tend to form when the skin is rubbed (Nikolsky sign).
There are currently 6 subtypes:
- Pemphigus erythematosus
- Pemphigus herpetiformis
- Endemic pemphigus foliaceus
- IgA pemphigus foliaceus
- Paraneoplastic pemphigus foliaceus
- Drug-induced pemphigus foliaceus
What causes pemphigus foliaceus?
Like the other Pemphigus diseases, Pemphigus foliaceus is an autoimmune disease. The building block cells of the epidermis are called keratinocytes. These cells are cemented together at special sticky spots called desmosomes. In pemphigus foliaceus autoantibodies bind to a protein called desmoglein-1, which is found in desmosomes in the keratinocytes near the top of the epidermis. The result is the surface keratinocytes separate from each other, and are replaced by fluid: the blister. Because the blister is very close to the surface of the skin the blisters rupture easily. In most cases the autoantibodies are immunoglobulin type G (IgG) but in IgA pemphigus foliaceus the autoantibodies are type A (IgA).
Pemphigus foliaceus is sometimes provoked by sun exposure.
Endemic pemphigus foliaceus occurs in South America, where it is commonly known as Fogo Selvagem. It appears to be set off by a virus transmitted by an insect bite.
Penicillamine, nifedipine, captopril, enalapril or nonsteroidal anti-inflammatory drugs most often provoke drug-induced pemphigus foliaceus. If the drug is stopped, there is a 50% chance the pemphigus foliaceus will clear up.
Who gets Pemphigus Foliaceous?
Pemphigus foliaceus affects people of all races, age and sex. It appears most commonly between the ages of 50-60 years.
What are the symptoms of Pemphigus Foliaceous?
Pemphigus foliaceus is confined to the skin and there is little or no involvement of mucous membranes. This is in contrast to pemphigus vulgaris where there may be extensive mucous membrane involvement.
The patient with pemphigus foliaceus is usually otherwise in good health. Small fluid-filled blisters first form on the trunk. Because they form in the upper layers of the epidermis they rupture very easily and only erosions may be seen. On the face, scalp and upper trunk the lesions are often scaly and crusty on a red and inflamed base. A burning sensation or localised pain may be felt.
Although pemphigus foliaceus is often less severe than Pemphigus Vulgaris, the doses of medications required for control are similar (although some patients may be treated with drugs like dapsone, and may not require corticosteroids or immunosuppressives).