The skin is the largest organ of the body. In addition to serving as a protective barrier, the skin is involved in many additional functions of the body such as regulating internal body temperature. Five distinct layers make up the skin; each layer is filled with specialized cells. The two main structural layers of the skin are the epidermis – the outermost, protective layer of skin – and the dermis – an underlying layer that contains numerous specialized cells, tissues and structures. Specialized proteins and structures are required for the dermis and epidermis to stick together. When the epidermis separates from the dermis a blister (bulla) may form.

A blister can be either tiny or large and consists of a fluid-filled bubble that forms underneath the surface of damaged or dead skin. Most blisters develop in response to irritation or injury of the skin. In autoimmune blistering diseases, blisters form because the body creates antibodies that attack certain proteins required for the proper health and function of the skin. In many cases, blisters can rupture becoming open sores or wounds.

In some autoimmune blistering diseases, blisters or lesions can also form on the mucous membranes, the thin, moist coverings of many of the body’s internal surfaces. Mucous membranes line the esophagus and anus, the inside of the mouth, the nasal passageways, the genitals and the throat. Associated symptoms depend on the location of blister formation, but can include gastrointestinal bleeding, difficulty swallowing or difficulty breathing.

There are several different categories of autoimmune blistering diseases including pemphigus, pemphigoid, IgA-mediated dermatoses and epidermolysis bullosa acquista. Pemphigus, pemphigoid and IgA-mediated dermatoses can be further broken down into additional subtypes.