There are two major subtypes of IgA pemphigus: (1) subcorneal pustular dermatosis-type, and (2) intraepidermal neutrophilic-type.
The subcorneal pustular dermatosis-type is characterized by IgA autoantibodies directed against desmocollin 1, with a neutrophilic infiltrate localized to the upper epidermis, just beneath the stratum corneum. The intraepidermal neutrophilic-type is characterized by a heterogeneous group of autoantigens (including desmoglein 1 or desmoglein 3), and it yields a neutrophilic infiltrate confined to the lower portions of the epidermis.
Epidemiological data on IgA pemphigus is limited. Studies suggest a slight predominance among women with an average age of onset in the sixth decade, although the condition has been reported in patients ranging in age from 1 month to 80+ years. The clinical phenotype of IgA pemphigus is generally milder than other forms of pemphigus, although significant morbidity may be observed on occasion.
Associated diseases include gastrointestinal disorders (eg, inflammatory bowel disease and dermatitis herpetiformis), monoclonal gammopathies, autoimmune diseases (eg, Sjögren syndrome and rheumatoid arthritis), and malignancies (eg, multiple myeloma, lung cancer, and lymphoma).
L10.89 – Other pemphigus
402717008 – IgA Pemphigus
- Sneddon-Wilkinson (classic subcorneal pustular dermatosis) – Identical clinical and histologic features of IgA pemphigus, but the direct immunofluorescence in Sneddon-Wilkinson is negative.
- Pemphigus foliaceus – Look for superficial, fragile vesicles or bullae upon the scalp, face, and trunk in a seborrheic distribution.
- Bullous impetigo – Superficial, flaccid vesicles that progress to serous or yellow-filled bulla with minimal erythema. Secondary yellow crusting is common.
- Linear IgA bullous dermatosis of childhood – Look for grouped or annular papules, vesicles, or bullae on the extensor surfaces and buttocks. New lesions may present at the peripheral edge of a previous blister giving it a "crown of jewels" appearance.
- Pustular psoriasis – Localized or widespread, erythematous, sterile pustules that may be distributed in "sheets" or in a more localized, annular pattern.
- Dermatitis herpetiformis – Classically presents as fragile, clustered vesicles commonly on the elbows, knees, and buttocks in the setting of an underlying gluten-sensitive enteropathy.