Peritoneal melanosis: case report and literature review

Peritoneal melanosis is a rare benign pigmentation disorder of the peritoneum, often discovered incidentally during surgery, alarmingly mimicking metastatic melanoma. We present the case of a 35-year-old female, who underwent emergency repair for a strangulated umbilical hernia. Intraoperatively, a 0.5 cm pigmented nodule was incidentally found on the pelvic peritoneum, alongside a similar ovarian lesion. An excisional biopsy was performed to rule out malignancy. Histopathological examination revealed fibro-adipose tissue with a dense inflammatory infiltrate and pigment-laden macrophages, confirming peritoneal melanosis. With fewer than 20 cases reported in the literature, this condition poses a significant intraoperative diagnostic challenge. Awareness is crucial for surgeons and pathologists to prevent the misdiagnosis of melanoma and prompt appropriate investigation for frequently associated occult ovarian or gastrointestinal lesions.