[Pyoderma gangrenosum].

Pyoderma gangrenosum is a very strange disease usually diagnosed on clinical grounds only and without any characteristic biological disturbance. It must be neither missed nor diagnosed too easily at the expense of vascular or infective ulcerations which are much more frequent. Its physiopathology remains shrouded in mystery since the abnormalities that have been found were extremely varied and sometimes conflicting, and were observed in short series. Thus, pyoderma gangrenosum appears as a syndrome which if often causeless or due to multiple diseases and might well be split into different entities in the forthcoming years. Despite its obscure pathogenesis, most patients can be cured by systemic corticosteroid therapy, sulfones or clofazimine. The main point of interest of that disease is that in almost 50 percent of the cases it is associated with a severe underlying pathology.