Autoimmune bullous skin diseases. Part 2: diagnosis and therapy.

Autoimmune bullous skin diseases represent a heterogenous group of disorders of skin and mucosa which are commonly associated with IgG or IgA autoantibodies against distinct adhesion molecules of the skin. The antibodyinduced loss of adhesion between epidermis and dermis results in blister formation and extensive erosions. There is a great need for rapidly establishing the diagnosis of these disorders since they may run a severe and potentially life-threatening course. In addition, because of their rarity and heterogeneous symptoms, autoimmune bullous skin diseases often pose a major diagnostic challenge. While histopathological examinations provide evidence for the level of blister formation, immunofluorescence microscopy has been established to identify tissue-bound and circulating autoantibodies. Direct immunofluorescence microscopy represents the gold standard for detecting tissue-bound autoantibodies. Indirect immunofluorescence microscopy with defined tissue substrates is considered the first step in detecting circulating autoantibodies. Confirmatory tests such as ELISA, immunoblot or immunoprecipitation analyses are performed utilizing recombinant proteins or keratinocyte extracts. The later assays can be used for primary diagnosis as well as for immunoserological follow-up. Systemic immunosuppressive drugs usually represent the main therapeutic regimen. Initially, systemic corticosteroids are commonly administered in combination with steroid-sparing, immunosuppressive agents. Novel targeted treatments such as immunoadsorption, rituximab or high-dose intravenous immunoglobulins have proven to be highly effective in severe and refractory pemphigus. This review presents a state-of-the-art algorithm for making the diagnosis of autoimmune bullous disorders and provides an overview on currently available therapeutic options.