[Pathogenesis of pyoderma gangraenosum].

Pyoderma gangraenosum (Pg) is regarded as an indicator of internal primary diseases of mainly auto-immunological character. Gammopathies as basic diseases are very often of the IgA-type. In contrast to the characteristic clinical picture we have observed unspecific, cellular traits. New investigations have reported immunological findings such as deposition of IgG and IgM as well as C3-complexes at the vascular walls. A decreased function of T-cells is described. Pg often develops in consequence of minor traumata. In these cases the disproportion between the primary lesion and the ulcerous process becomes obvious. By presentation of a typical case in addition to a literature survey, it is discussed whether the primary disease is responsible for this development. Because of the close relationship between Pg and the underlying immunopathology it is proposed that Pg - in analogy to the neoplastic cutaneous syndrome - be classified dipolar-like as a paraimmunological syndrome.