A case of malignant melanoma simultaneously found in the lung and small intestine.

Metastatic melanoma in the small bowel is a common cause of secondary intestinal tumors. We present a case of a 77-year-old man with melena resulting from melanoma in the small bowel that was simultaneously found with malignant melanoma in the lung. Abdominal contrast-enhanced computed tomography (CT) and position emission tomography (PET) revealed a 30 × 20 mm hypervascular lesion in the small bowel and a 9 × 9 mm right lobe lung mass with metastasis in the mediastinal and peritoneal lymph nodes, and the spleen. The bowel and lung tumor lesions were confirmed by enteroscopy and bronchoscopy, respectively, and were histologically diagnosed as malignant melanoma. In cases of small bowel malignant melanoma, an extraintestinal origin should always be suspected because intestinal melanomas are almost always metastatic. PET/CT is an effective tool for confirming intestinal melanomas because of its high sensitivity and specificity.