Primary colonic malignant melanoma.

摘要: Primary malignant melanoma originating in the digestive tract is extremely rare. A case of primary descending colon described. The tumor was an elevated mass with surface necrosis. Histologically, cells were arranged compact nests surrounded by fibrous stroma. had pleomorphic nuclei and rich cytoplasm. In some areas, signet ring-like appearance found. An immunohistochemical examination showed that most positive for S-100 protein, HMB-45, melan-A, vimentin CD38. Ultrastructural confirmed premelanosomes. EWS-ATF-1 fusion transcript, which usually detected clear cell sarcoma, not demonstrated on reverse transcriptase-polymerase chain reaction. Because there no evidence either cutaneous or ocular melanoma, thus diagnosed as colonic melanoma. patient has remained free recurrent disease 3 years after a surgical resection. Colonic must be differentiated from other intestinal tumor, possibility metastasis another more common site ruled out.