Case Report of Primary Rectal Melanoma and Review of the Etiology of Melanoma

Abstract

Primary rectal melanoma is a very rare and aggressive malignancy. It is defined as melanoma arising in the rectal mucosa, more than 4 cm from the anal verge. A case of primary rectal melanoma is reported, and the theories of the etiology of melanoma are reviewed. This article reports a case of a 75-year-old woman who presented with lower gastrointestinal bleeding and abdominal discomfort. A polyp was removed from the low-lying rectum during colonoscopy. After immunohistochemical staining and microscopic examination, it was diagnosed as melanoma. In light of primary melanoma in sun-shielded regions such as the rectum, theories of causation other than sun exposure merit consideration. Factors such as genetics, immunosuppression, and virus infections, as well as ultraviolet radiation, may play a role in the etiology of melanoma.