Ileus secondary to a retroperitoneal malignant melanoma

Retroperitoneal malignant melanomas, either primary or metastatic, are rare. We present our clinical experience concerning one case with ileus secondary to a huge retroperitoneal malignant melanoma. A 77-year-old woman was admitted to the hospital due to progressive abdominal fullness and decreased appetite for 4 months. Plain films showed soft-tissue density in the left lower quadrant of the abdomen, as well as rightward displacement of the intestine. Laboratory data excluded any metabolic or septic causes of ileus. Abdominal computed tomography scan identified a huge retroperitoneal tumor with invasion of the left lower peritoneal space. The mass measured approximately 18.2 × 21.5 cm in the largest section. Immunohistochemical analysis of the tumor biopsies at minilaparotomy showed positive staining of tumor cells for S-100 protein, human melanoma black-45, and vimentin. Thus, a diagnosis of malignant melanoma with peritoneal metastases was established. This case highlights the possibility of a retroperitoneal malignant melanoma exerting a mass effect on the surrounding organs. The authors suggest that malignant melanoma should be taken into consideration as a possible differential diagnosis of retroperitoneal neoplasms.