A 3-week-old full-term African American boy presented for evaluation of a perianal ulcer (Figure 1) that had begun to develop on the third day of life. He was not febrile and was otherwise feeding well and thriving. He had been admitted to 2 hospitals and treated intravenously with both clindamycin and ampicillin-sulbactam, without improvement.
Physical examination revealed a 1-cm shallow ulcer with a slightly rolled border and surrounding erythema on the right buttock near the anal verge. There was a similar 5-mm shallow ulcer superiorly. A 3-mm punch biopsy specimen was obtained from the edge of the ulcer and stained with hematoxylin-eosin (Figure 2).
Knispel J, Shaw JC. Nonhealing Perianal Ulcer. Arch Dermatol. 2001;137(3):365-370. doi: