Melanoma metastatic to the gallbladder and small bowel: report of a case and review of the literature

From post-mortem case records, the small bowel is the most frequent site of metastatic melanoma in the gastrointestinal (GI) tract, with gallbladder involvement occurring in 15% of cases. However, few cases have been documented in living patients and, when found, are associated with a poor prognosis. We report a case of a Caucasian man with metastatic gallbladder and small bowel melanoma from an unknown primary. He presented with diffuse abdominal pain, vomiting and progressive asthenia; subsequently, intestinal obstruction occurred. He had no past history of malignant melanoma and the primary lesion was not found. The multiple lesions, together with the absence of mucosal involvement in both the gallbladder and small bowel, led us to believe that the lesions were metastatic deposits from a probably regressed primary melanoma. It should be emphasized that surgical resection for melanoma metastatic to the GI tract is recommended for palliative reasons and can be performed safely. The clinical presentation, diagnosis, treatment and prognosis of previously reported cases of melanoma metastatic to the gallbladder and small bowel are reviewed. The differences between primary and secondary GI tract melanomas are also discussed.