Variations in gastrointestinal melanoma metastases.

In 10 patients with gastrointestinal metastases from cutaneous malignant melanoma, metastases to the stomach were found in 2, the small bowel in 9, and the large bowel in 3. Gastric metastases typically appeared as target lesions. However, the morphology of secondary melanoma deposits to the small and large intestine varied significantly, target lesions being only one possible manifestation. Less common appearances of gut metastases were found in 4 patients. One presented atypically with matted loops of distal ileum resulting in prolonged stasis of barium in the affected areas. In 3 patients, infiltrative and stenotic lesions were found in the distal ileum, terminal ileum and cecum. One stenotic lesion of the distal ileum was accompanied by multiple small polypoid lesions more proximally, and the cecal lesion was ulcerated. Six of the patients presented with polypoid and, occasionally, ulcerated and multiple secondary melanoma deposits. Possible causes for variations in morphology are discussed.