Mucous membrane pemphigoid
Editor-In-Chief: C. Michael Gibson, M.S., M.D. ;Associate Editor(s)-in-Chief: Kiran Singh, M.D. 
Mucous membrane pemphigoid, also known as cicatricial pemphigoid (which means scarring pemphigoid) is a skin-blistering autoimmune disease. This is a rare condition with an incidence of approximately one in a million of the population.
In mucous membrane pemphigoid, the autoimmune reaction occurs in the skin specifically at the level of the basement membrane, the layer that holds the skin to the underlying tissue. When the condition is active, the basement membrane is dissolved by the antibodies produced, and areas of skin lift away at the base, causing hard blisters which scar if they burst. In other words, this is a desquamating/blistering disease in which the epithelium "unzips" from the underlying connective tissue, allowing fluid to gather that subsequently manifest as bullae, or blisters.
Differentiating Mucous Membrane Pemphigoid from other Diseases
Epidemiology and Demographics
Natural History, Complications and Prognosis
The autoimmune reaction most commonly affects the mouth, causing lesions in the gingiva or gums, but can also affect areas of mucous membrane elsewhere in the body, such as the sinuses, genitals and anus. When the cornea of the eye is affected, repeated scarring may result in blindness.
antibodies (IgG) precipitates complement (C3) in the lamina lucida of the basement membrane. Circulating auto-antibodies to BP-1 antigen (located in hemidesmosome). 50% have BP-2. Positive Nikolsky sign. IgG, C3 deposition at BM creating smooth line in immunofluorescent analysis.