Summary
Pemphigus is a group of chronic autoimmune skin diseases characterised by blisters formation on the outer layer of the skin and the mucous membranes. Three clinical forms have been characterised, of which paraneoplastic pemphigus is extremely rare. The prevalence of this form of pemphigus is unknown. More than 60 cases have been published so far. Paraneoplastic pemphigus occurs in a background of suspected or proven neoplasia. The associated cancers are mostly lymphomas, chronic lymphoid leukaemia and in some cases, Kaposi sarcoma, thymomas, carcinomas, and poorly differentiated sarcomas. The disease almost always begins with severe diffuse blisters (bullae) in the mouth, on the lips and on the oesophagus. Eyes are frequently involved. Skin lesions vary and can be misleading, presenting as bullous lichenoid lesions, evocative of urticaria or polymorphous erythema. Lungs can also be involved (in 30% to 40% of cases), as well as the gastrointestinal tract. Histopathological analysis shows intra-epidermal acantholysis with the presence of necrotic keratinocyte cells, vacuolisation of the basal layer and dermic lichenoid inflammatory infiltrate. Direct immunofluorescence test shows linear IgG deposits at the dermo-epidermal junction, as well as linear or granulous deposits of complement on the basal membrane. IgA and IgM can also be detected. Anti-plakine antibodies can be present, as well as anti-desmoglein 1 and 3 antibodies. The progression of paraneoplastic pemphigus rarely parallels neoplastic progression. Immunosuppressant drugs are often required. Paraneoplastic pemphigus is often fatal (in 90% of cases), however, the prognosis is improved when the associated tumour is benign. *Author: Orphanet (November 2007)*.
