Clinical analysis of anorectal malignant melanoma

Abstract

To summarize the clinicopathological characteristics of primary anorectal malignant melanoma (AMM). Clinical data of nine patients with AMM were reviewed retrospectively from January 1999 to March 2005. Anorectal malignant melanoma had a female predominance. The average age was 56 years old and average course of disease was 5.8 months. The onset of symptom was hematochezia, then anus prolapses. 94.7% of patients had AMM within 5 cm from anus margin; the average tumor size was (3.3+/- 2.1) cm. The polyp and ulcer were most common types. More than a half (54.5%) of the tumor was movable, 19.1% smooth surfaced, 6.6% soft textured. Synchronous metastasis was found in 14.0% of the patients, the first common metastasis was found in liver, the secondary was superficial inguinal lymph node metastasis. Half of the patients were misdiagnosed,and over 50% of patients were misdiagnosed as benign disease. Mile's operation was performed in most of patients (63%), while anal resection was performed in 30% of the patients. Anorectal malignant melanoma is often misdiagnosed,surgical procedure is the first choice for patients with AMM.