Congenital Peri Anal Lipoma, a Case Report and Review

Background: Congenital lipoma is a rare benign tumor in infants, commonly affecting areas such as the trunk, neck, abdomen, forearms, buttocks, and thighs. However, it is infrequently observed on the face, scalp, and calves. Perineal lipomas are exceedingly rare and are typically associated with genitourinary or anorectal anomalies, with isolated cases being extremely uncommon. Case Summary: A 2-year-old male child presented with a perianal mass for evaluation. The prenatal, perinatal, and postnatal histories were unremarkable, and there were no significant medical issues. At birth, a soft, round, 1.5 cm mass was noted to the left of the anal verge. Despite the mass, the child had normal urinary and bowel function and was discharged without intervention. MRI revealed a fat-signal intensity lesion measuring 7 × 5 cm in the left perianal space, causing lateral displacement of the anal canal. No associated anomalies, such as spina bifida or bladder dysfunction, were identified. The lesion was surgically excised along with surrounding subcutaneous tissue while preserving the external sphincter muscle. Post-surgical assessment using an electrical muscle stimulator confirmed intact sphincter function. The surgical site was closed with interrupted sutures. Gross examination demonstrated a well-circumscribed, yellowish, lobulated fatty mass measuring 7 × 5 cm. Histopathological analysis confirmed the diagnosis of benign lipoma, composed of mature adipose tissue and fibrovascular trabeculae, with no evidence of malignancy. The patient experienced an uneventful recovery with normal bowel function and satisfactory cosmetic results. A follow-up period of 1.5 years showed no recurrence or complications. Conclusion: Careful physical examination at birth, coupled with magnetic resonance imaging (MRI) and contrast enema studies, is critical for characterizing perineal lipomas and identifying associated anomalies. Surgical excision requires meticulous planning, especially when the lesion is deeply embedded near the sphincter muscles or accompanies anorectal anomalies. The use of an electrical muscle stimulator during resection helps preserve sphincter integrity, ensuring optimal postoperative bowel function.