1. A disease resembling pemphigus but significantly distinguishable histologically and clinically.
2. A blistering disease of the elderly that often starts with uriticarial or pruritic erythematous lesions which later develop large tense blisters.

The bullae (large vesicles or blisters) are subepidermal (immediately below the upper skin), and intact epidermis forms the roof. Immunoglobulin and complement are found in the basement membrane zone in perilesional skin (around a break or infection in the skin) and circulating antibodies specific for this site are found in the majority of subjects.

A chronic, generally benign disease, most commonly of old age, caused by antibodies that accumulate abnormally in a layer of the skin called the basement membrane: "Bullous pemphigoids can be chronic, mild and not affect the general health or they can be severe and compromise the health of the sufferer."

"Although most cases of bullous pemphigoids are in older people, the disease can affect younger people, and even babies."

"The diagnosis of bullous pemphigoid can be confirmed by a skin biopsy showing the abnormal antibodies deposited in the skin layer and treatment is with topical cortisone creams; however, severe cases may sometimes require high doses of cortisone-like drugs (steroids) or immune suppression drugs; such as, azathioprine (Imuran). Azathioprine attacks proteins that the immune system considers to be foreign."