Case report of primary rectal melanoma and review of the etiology of melanoma.
BACKGROUND
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.


OBJECTIVE
A case of primary rectal melanoma is reported, and the theories of the etiology of melanoma are reviewed.


RESULTS
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.


CONCLUSIONS
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.
Division of Dermatology, University of Ottawa, Ottawa, Ontario, Canada. lfrat038@uottawa.ca
Lauren
L
Fratesi
Raed
R
Alhusayen
James
J
Walker
D000368:Aged; D003113:Colonoscopy; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008545:Melanoma / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000209:etiology / Q000601:surgery