Primary malignant melanoma of the right colon.

The small and large intestines are the most common sites for metastases from cutaneous malignant melanoma. However, primary melanomas in these sites are exceedingly rare. There are several case reports of patients with primary melanoma of the small bowel, but finding of a solitary primary melanoma in the colon is exceedingly rare. We describe a patient that was operated on for bowel obstruction due to colonic intussusception resulting from a right colonic tumor. Histopathological examination confirmed a diagnosis of malignant melanoma. A thorough postoperative investigation did not reveal a primary lesion in any other site. Two years after surgery, there was no evidence for recurrent disease. The treatment and prognosis of metastatic and primary melanoma of the gastrointestinal tract is discussed as well as the embryonic base for development of primary malignant melanoma of the intestine. Primary malignant melanoma of the intestine is an extremely rare lesion that may arise in the large bowel as well. It must be differentiated from other intestinal tumors and mandates a thorough investigation to rule out the possibility of being a metastasis from another more common primary site.