대한대장항문학회

Although anal canal is the most common site for the development of malignant<br>melanoma in the alimentary tract, it is extremely rare and melanoma can occur primarily<br>at lower rectum. Anorectal melanoma constitutes 0.4% to 0.8% of colorectal malignancies<br>and less than 2% of melanomas. The prognosis may depend on the extent of disease<br>and depth of invasion. It generally seems to be very poor in spite of aggressive<br>treatment. We have treated four patients of rectal melanomas out of 1,477 cases of all<br>colorectal cancer between September, 1989 and January, 1997 ; a 39-year-old female<br>with the intermittent blood-tinged stool, a 51-year-old male with hematochezia, a<br>59-year-old male with anal bleeding and a 65-year-old female with anal bleeding. They<br>were treated by abdominoperineal resection with pelvic lymph node dissection and<br>were confirmed histologically rectal melanomas.<br>