Objective: To summarize the clinicopathological characteristics of primary anorectal malignant melanoma (AMM).
Methods: Clinical data of nine patients with AMM were reviewed retrospectively from January 1999 to March 2005.
Results: 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.
Conclusions: Anorectal malignant melanoma is often misdiagnosed,surgical procedure is the first choice for patients with AMM.