A 66-year-old white woman presented with a black necrotic ulcer on the lateral aspect of her face. The lesion had developed over 6 days, beginning as an erythematous plaque. The patient's medical history included a renal transplantation 2 months before the lesion appeared, and her medications included cyclosporine, azathioprine, and prednisolone. There was no history of trauma to her face.
Physical examination revealed a large 3.5-cm necrotic ulcer with an erythematous border on the patient's face, next to her left eye (Figure 1). Routine laboratory investigations showed a C-reactive protein level of 20.4 mg/dL (reference value, <0.5 mg/dL) and a white blood cell count of 4.6 × 109/L (reference range, 4.0-10.0 × 109/L). The patient's fasting blood glucose level was 8.7 mmol/L (156 mg/dL). Two biopsy specimens from the peripheral part of the lesion were obtained for culture and pathologic examination. They were stained with hematoxylin-eosin (Figure 2).