Pemphigus is a rare, non-contagious skin disorder in which blisters form on a person’s skin or mucous membranes (tissue lining of body cavities). In rare cases, pemphigus may spread into the bloodstream or lungs. Left untreated, this condition can be fatal. Painful, crusting blisters are the most common symptom of pemphigus.

There are three major types of pemphigus:

• Pemphigus vulgaris. The most common form of the disease, it typically begins in the mouth and then spreads to the skin.
  
  
• Pemphigus foliaceus. In most cases, this form of pemphigus only affects the skin and not the mucous membranes.
  
  
• Paraneoplastic pemphigus. This form of the disease tends to cause painful sores that form in the mouth, throat and on the lips. Patients also may develop lesions on the skin and lungs.

Scientists remain unsure of the cause of pemphigus, but believe it is caused by an autoimmune disorder in which the immune system attacks healthy proteins called desmogleins. These proteins bind skin cells together, and when they are destroyed the top layer of the skin (epidermis) begins to separate.