Bullous pemphigoid: A disease characterized by tense blisters on the skin. The condition is caused by antibodies that accumulate abnormally in a layer of the skin called the basement membrane. The antigen of this autoimmune disease is localized to the hemidesmosome. Most cases of the disease are in older people but the disease can affect younger people, even babies. Bullous pemphigoid can be chronic, mild and not affect the general health or it can be severe and compromise the health of the sufferer. The diagnosis can be confirmed by a skin biopsy showing the abnormal antibodies deposited in the skin layer. Treatment is with topical cortisone creams, but especially severe cases may sometimes require high doses of cortisone-like drugs (steroids) or immune suppression drugs, such as azathoprine (Imuran).