Pemphigus (/ˈpɛmfɪɡəs/ or /pɛmˈfaɪɡəs/) is a rare group of blistering autoimmune diseases that affect the skin and mucous membranes.

In 1964, researchers found that the blood of patients with pemphigus contained antibodies to the layers of skin that separate to form the blisters.

[13] Definitive diagnosis requires examination of a skin or mucous membrane biopsy by a dermatopathologist or oral pathologist.

Thus, the superficial (upper) portion of the epidermis sloughs off, leaving the bottom layer of cells on the "floor" of the blister.

These antibodies appear as IgG deposits along the desmosomes between epidermal cells, a pattern reminiscent of chicken wire.

One of the most dangerous side effects of high-dosage steroid treatments is intestinal perforations,[citation needed] which may lead to sepsis.

A meta-analysis of the literature found insufficient evidence to determine the optimal treatment regimen for pemphigus vulgaris and pemphigus foliaceus, but it found that adding cyclophosphamid and azathioprine to a glucocorticoid regimen reduced the amount of glucocorticoid needed for treatment, and topical epidermal growth factor significantly reduced lesion healing time.

If paraneoplastic pemphigus is diagnosed with pulmonary disease, a powerful cocktail of immunosuppressant drugs is sometimes used in an attempt to halt the rapid progression of bronchiolitis obliterans, including methylprednisolone, ciclosporin, azathioprine, and thalidomide.

[22] Pemphigus foliaceus has been recognized in pet dogs, cats, and horses, and is the most common autoimmune skin disease diagnosed in veterinary medicine.