Pyoderma gangrenosum mimicking a diabetic foot infection: a case report.

An adult with ulcerative colitis and diabetes presented with a painful, swollen, edematous left foot. Diagnostic images and laboratory tests were inconclusive. Antibiotics were started immediately but aggravated his symptoms, and the laboratory results worsened. His foot was debrided twice per protocol for treating diabetic foot ulcers or cellulitis. After debridement, his condition worsened rapidly. Pyoderma gangrenosum was correctly diagnosed on the basis of massive neutrophilic infiltration detected in the biopsy tissue and because the lesion was well-defined and colored deep red to violet, unlike the bullosis diabeticorum blisters observed in the diabetic foot. His foot improved with systemic corticosteroids and topical wound care, and a skin defect was treated with a skin graft. After 9 months, his foot was well healed. Pyoderma gangrenosum can be diagnosed by careful examination and must be distinguished from an ulcerated diabetic foot lesion.