Multiple colonic polyps as the initial presentation of malignant melanoma

A 72-year-old-man was admitted to the Charleston Area Medical Center with a one-month history of mild anemia and positive stools for occult blood. A prior UGI series, small bowel series, and barium enema were normal. A colonoscopy revealed 12 sessile, non-pigmented colonic polyps, two of which were removed and sent for histologic examination. The final pathology report revealed malignant melanoma. Physical examination revealed no obvious evidence of skin lesions or melanoma elsewhere. Subsequent staging, which included a chest X-ray, a CT scan of the abdomen and brain, UGI endoscopy, and bone scan revealed a metastatic disease. The colonic lesions regressed in response to combination chemotherapy, and the patient's transfusion requirement decreased. However, the patient died of brain metastases 10 months after the initial diagnosis. This case emphasizes the fact that: 1. Metastatic lesions of the gastrointestinal tract may be the initial manifestation of malignant melanoma and may occur in the absence of a clinically obvious lesion; 2. Colonic metastases may simulate simple polyps endoscopically, particularly if they are non-pigmented; 3. Biopsy and histologic examination of any colonic polyp is essential in patients with a prior history of melanoma; and 4. Regression of gastrointestinal lesions from melanoma and subsequent clinical improvement may occur in response to chemotherapy.