Synchronous metastatic omental melanoma and colonic adenocarcinoma: a case report

BACKGROUND: Malignant melanoma is a rare malignancy of the skin with very high mortality rates. Distal metastases are common especially to other areas of the skin, subcutaneous tissues lungs or liver. There are no previously reported cases of skin melanoma metastasizing to the omentum. CASE PRESENTATION: A 62 year-old white British man with a past medical history of a malignant melanoma of the skin underwent a laparotomy for a partially obstructing sigmoid tumour. Intra-operatively, a round, smooth textured black lesion was identified on the anterior surface of the omentum; the nodule was confirmed to be a metastatic malignant melanoma with abundant brown pigment and a focal necrotic area. CONCLUSION: A metastatic malignant melanoma was discovered incidentally on the omentum during a laparotomy for bowel obstruction. The significance of this is unclear but it is possible that the omentum may have played a protective role in limiting its spread systemically.