Sporotrichosis masquerading as pyoderma gangrenosum.

A 46-year-old man was diagnosed as having pyoderma gangrenosum after special stains and cultures from a skin biopsy specimen were reported as negative. Cutaneous sporotrichosis is usually diagnosed with relative ease on the basis of clinicopathologic features and prompt growth of the fungus in culture, although organisms are difficult to detect in tissue even with special stains. Identification of Sporothrix schenckii was delayed for three months in this patient because of unusual growth characteristics noted in the culture. The report of this patient's clinical course illustrates both the need to frequently reassess the diagnosis of pyoderma gangrenosum in treatment-resistant patients and the fact that S schenckii may be difficult to diagnose clinically and mycologically if the growth characteristics of the fungus are unusual.