Colonic melanoma, primary or regressed primary

Primary melanoma originating in the gastrointestinal tract is very rare and the majority of these tumors arise in the mucosa of the anus or rectum, A case of solitary colonic melanoma in a 79-year-old man is described with a review of pertinent literature. The surgically excised neoplasm was evaluat ed by routine histology and immunohistochemistry stains. Pathologic examina tion of the excised cecal mass revealed an 8 x 5-cm tan-pink mass with a ce ntral green-black necrotic area. Histologically, there were solid sheets of S100- and HMB-45-positive pigmented cells extending from the mucosal ulcer ated surface through the bowel wall, The patient had no evidence of cutaneo us or ocular primary melanoma. He remained free of recurrent disease 5 year s after surgical resection of the colonic melanoma. The unique pathologic f eatures and clinical outcome support the diagnosis of primary colonic melan oma in this patient.