[An unusual case of pyoderma gangrenosum with necrotizing granulomatous dermatitis].

Four distinctive clinical and histological variants of pyoderma gangrenosum have been proposed: (1) ulcerative, (2) pustular, (3) bullous, and (4) vegetative. The rate of progression and associated systemic diseases, as well as the histopathologic changes, can vary considerably between these clinical variants. A 64-year-old man presented with ulcerative pyoderma gangrenosum associated with renal cell carcinoma and IgA paraproteinemia; he responded to oral thalidomide. Histopathology revealed unusual findings with signs of leukocytoclastic vasculitis, basophilic degeneration of collagen and zones of suppuration with a palisaded histiocytic and epithelioid granulomatous infiltration throughout the dermis.