Abstract
We report a case of amelanotic malignant melanoma of the anorectum with a review of 154 cases of malignant melanoma of the anorectum, especially 11 of amelanotic form including this case, seen in the Japanese literature. A 33-year-old woman complaining of proctorrhagia was diagnosed as the disease by excisional biopsy and histological examination of the biopsy specimen, which were performed under a probable diagnosis of rectal polyp. Low anterior resection was carried out. The patient is closely followed on ambulant basis, and no recurrence has been observed for 3 years and one month after operation. Amelanotic form is slightly common in younger patients compared to melanotic form. The male-to-female ratio was 1 to 10. More than half lesions arose in the rectum. Prognosis of malignant melanoma was poor in cases having distant and/or lymphnode metastasis. No significant difference was found by whether biopsy was performed or by operative procedures.
