[Primary ano-rectal melanoma]

Abstract

Primary malignant anorectal melanoma is an uncommon disease that accounts for 1% of anorectal malignancies. Its virulent malignancy is associated with a poor prognosis and with difficult diagnostic and therapeutic problems. The operative management of these patients is controversial. Clinicopathologic features and surgical treatment of 6 patients with primary anorectal melanoma were studied retrospectively. There was a male preponderance (2:1) with a mean age of 62 years (range: 34-74). The site of origin of the melanoma was rectal in one patient and in the anorectal junction in five patients. Atypical intramucosal melanocyte proliferation was associated with rectal melanoma. The maximum tumor size from 2 to 5.5 cm. Common initial symptoms were rectal bleeding and/or tenesmus. CT was useful for tumor staging. Two patients had distant metastases at initial presentation. Four patients underwent "curative" treatments by abdominoperineal resection and 2 by local excision. The survival for the group as a whole was poor (mean: 12.6 months; range: 7-30 months). Surgery is the primary option. The prognosis, however, is poor, since metastatic disease is commonly established at presentation. Atypical intramucosal melanocyte proliferation may be a marker in association with tumor sited in the rectum.