Non-thrombocytopenic purpuras

88 cases of microscopical diapedesis of the red blood cells in the superficial blood vessels of the skin were investigated clinically, histologically and immunohistologically. Polymorphonuclear vasculitis (PMNV) was found in 27 cases, 18 of which also demonstrated immunoglobulins (mostly IgM) in the vessel walls. Complement (C3) was found in 16 cases. The cases with PMNV formed a uniform group as regards preceding infections, drug consumption, clinical features, and pathological urinalysis and laboratory data. The second group consisted of 21 cases of lymphocytic perivasculitis with immunoglobulins and/or complement (LP + ig/C3). It clearly differed clinically from the former group in three respects: urinalysis was normal, a slowing of the venous outflow was found in more than half of the cases and the duration of the disease was longer. The biggest group consisted of 40 cases of lymphocytic perivasculitis without detectable immunoglobulins in the vessel walls (LP). In this group the duration of the disease was shortest. The capillary resistance was lower than in the other groups. The results of this investigation indicate that there are at least three pathogenetically differing groups among the clinical purpuric conditions.