黑色素瘤主要发生于皮肤,也可发生于黏膜,其发病率占皮肤恶性肿瘤的7%~20%~([1])。直肠肛管原发性恶性黑色素瘤(anorectal malignant melanoma,ARMM)仅次于皮肤黑色素瘤和眼睛黑色素瘤,位居第3位,但其发病率仅占肛管恶性肿瘤的4%~([2]),而且病理组织形态变化多样,当缺乏黑色素时,其误诊率高达80%~([3])。作者医院诊治1例原发性肛管直肠 Melanoma occurs mainly in the skin, can also occur in the mucosa, the incidence of skin cancer accounted for 7% to 20% ~ ([1]). Rectal anal primary malignant melanoma (anorectal malignant melanoma, ARMM) after the skin melanoma and eye melanoma, ranked No. 3, but the incidence of anal canal malignant tumors accounted for only 4% ~ ([2 ]), And the pathological changes in morphology, when the lack of melanin, the misdiagnosis rate as high as 80% ~ ([3]). A hospital diagnosis and treatment of primary anal canal