Paraneoplastic pemphigus.

Paraneoplastic pemphigus (PNP) is a distinct autoimmune blistering disease that can affect multiple organs other than the skin. It occurs in association with certain neoplasms, among which lymphoproliferative diseases are most commonly associated. The clinical presentation of PNP consists typically of painful, severe oral erosions that may be accompanied by a generalised cutaneous eruption and systemic involvement. The eruption may be of different morphology, consisting of lesions that resemble pemphigus, pemphigoid, erythema multiforme or graft versus host disease, as well as lesions resembling lichen planus. Similarly, the histological findings also show considerable variability. PNP is characterised by the presence of autoantibodies against various antigens: desmoplakin I (250 kd), bullous pemphigoid antigen I (230 kd), desmoplakin II (210 kd), envoplakin (210 kd), periplakin (190 kd), plectin (500 kd) and a 170-kd protein. This 170-kd protein has recently been identified as alpha-2-macroglobulin-like-1, a broad range protease inhibitor expressed in stratified epithelia and other tissue damaged in PNP. The prognosis of PNP is poor and the disease is often fatal. Immunosuppressive agents are often required to decrease blistering, and treating the underlying malignancy with chemotherapy may control autoantibody production. The prognosis is better when PNP is associated with benign tumours and these should be surgically excised when possible.