Pyoderma gangrenosum involving the head and neck.

In six patients with pyoderma gangrenosum, the head and neck region was a major site of ulcerative skin disease. In two patients, the disease was limited to this anatomic site. Corticosteroids were effective therapy in five cases. In one case, occurring in association with ulcerative colitis, total proctocolectomy was required to control ulcerative scalp disease. Detailed histologic examination of a primary lesion in one case with 0.5-micron sections demonstrated morphologic evidence of mast cell activation, suggesting that mast cells may contribute to the pathogenesis of the inflammatory process in pyoderma gangrenosum.