A 4-month-old term white girl was referred to pediatric dermatology by her pediatrician and a pediatric surgeon for evaluation of a congenital perineal lesion. The mother’s pregnancy was unremarkable, and the infant was healthy. The lesion had been stable and uncomplicated since birth. Barrier creams were attempted for presumed diaper dermatitis without response. Physical examination showed a well-demarcated, erythematous, superficial ulcer anterior to the anus (Figure, A). A fungal culture was negative. At the 1-month follow-up, the ulcer remained unchanged. The infant underwent 1 treatment with pulsed-dye laser for the possible diagnosis of ulcerated hemangioma, which led to improvement in the erythema. Six months later, when the ulceration remained largely unchanged, a skin biopsy was performed. Histologic specimens showed hyperkeratosis, hypergranulation, fibrosis, and vascular dilatation. Abdominal and pelvic ultrasonography was performed to rule out associated anomalies, and the findings were normal. A diagnosis of perineal groove was ultimately made clinically without further intervention. The lesion remained asymptomatic and stable at last follow-up, patient age, 16 months.