Abstract

BACKGROUND
Gastrointestinal tract melanomas are usually of metastatic origin, with primary melanomas being relatively rare. Controversy arises about the existence of primary melanoma in the gastrointestinal tract except in areas where melanocytes exist. The appearance of primary colon melanoma is rare due to the embryological absence of melanocytes in the large intestine, with some authors denying its existence at all.
CASE REPORT
We present a clinical case of a female patient with a primary melanoma of the descending colon. The patient came to the clinic with nausea without vomiting, abdominal swelling and pain, difficult and irregular defecation, and data on a tumor process of the left colon from the performed colonoscopy. Laparoscopic left hemicolectomy with lymphatic dissection was performed. The conclusion to be drawn from histological results was that the malignancy is poorly-differentiated adenocarcinoma. However, the immunohistochemical examination showed colon melanoma. Postoperative complete dermatological and ophthalmic examinations showed no evidence of a cutaneous or an ocular primary lesion, so we decided that this could be a primary colon melanoma.
CONCLUSIONS
Because of the colonoscopy we were able to make a detailed histological examination of the tumor, which allowed us to differentiate it from common colon adenocarcinomas. Surgical treatment is important in the removal of the primary tumor. The method of choice, with excellent postoperative results, is laparoscopic left hemicolectomy with selective cut-off of the colic vessels at the site of separation and removal of the affected segment together with the mesentery-bearing regional lymphatic basin.

Keywords: Histology, Comparative; Nevi and Melanomas; Colorectal Surgery; Colonoscopy