Skin ulcers misdiagnosed as pyoderma gangrenosum

Background: Pyoderma gangrenosum is a diagnosis of exclusion, and the misdiagnosis of pyoderma gangrenosum can result in substantial complications in patients who have other causes of severe cutaneous ulceration. Methods: We reviewed the charts of 240 patients with a diagnosis of pyoderma gangrenosum who were evaluated at our institution from 1975 through 2000, including 157 consecutive patients treated for presumed pyoderma gangrenosum from 1984 through 1992. We also reviewed the English-language literature. Results: Ninety-five patients (49 from our institution and 46 described in the literature) had skin ulcers with a clinical resemblance to pyoderma gangrenosum. The final diagnoses were vascular occlusive or venous disease, vasculitis, cancer, primary infection, drug-induced or exogenous tissue injury, and other inflammatory disorders. Of the 95 patients studied, 64 had been treated for pyoderma gangrenosum for a median of 10 months (range, 3 to 180). These 64 included 15 of the 157 consecutive patients treated for pyoderma gangrenosum at our institution (10 percent). Of the ulcers in the 64 patients treated for pyoderma gangrenosum, it was clear that those in 23 patients (36 percent) did not respond to treatment directed at pyoderma gangrenosum, those in 8 (12 percent) were exacerbated by such treatment, and those in 15 (23 percent) improved with such treatment. Conclusions: The misdiagnosis of pyoderma gangrenosum is not uncommon and exposes patients to risks associated with its treatment. A thorough evaluation is required in all patients suspected of having pyoderma gangrenosum in order to rule out alternative diagnoses.