肛管直肠恶性黑色素瘤6例临床病理分析

Clinical pathologic features and differential diagnosis of 6 cases of anorectal malignant melanoma

目的探讨原发性肛管直肠恶性黑色素瘤的临床特点、病理特征、鉴别诊断及误诊原因，避免误诊误治，从而为治疗及预后提供依据。方法对2005年1月至2014年2月河南省安阳市肿瘤医院收治的6例原发性肛管直肠恶性黑色素瘤患者的临床病理资料进行回顾性分析并进行随访，所有病理标本均进行免疫组化检测。结果临床误诊痔疮3例、息肉1例，肿瘤2例。肿物镜下形态主要表现实性片状或腺泡状结构，瘤细胞呈上皮样或梭形形态，导致误诊为肛管直肠低分化腺癌有4例，1例考虑为低分化鳞癌；总体病理误诊率达83．3％。随后免疫组化黑色素瘤特异性抗体S-100、Melan-A、HMB-45均为阳性。随访患者6例，例1至例5分别于30、42、26、46、52个月后死亡，例6患者术后拒绝化疗，28个月后死亡。结论原发性肛管直肠恶性黑色素瘤罕见，且组织形态多变，容易误诊为其他恶性肿瘤。随访发现，肿物大者、浸润深度、伴有淋巴结转移者及不接受化疗和生物治疗者生存期明显缩短。目前手术是主要的治疗手段，晚期患者采用化疗联合生物治疗以提高患者预后，但不甚明显。

Objective To study the clinical and pathological characteristics and differential diagnosis and misdiagnosis reasons of primary anorectal malignant melanoma, so as to provide some references for the treatment and prognosis. Methods The clinical and pathological data of 6 patients with primary anorectal malignant melanoma treated at our hospital from January, 2005 to February, 2014 were retrospectively analyzed. And the patients were followed up. All the pathological specimens were immunohistochemically detected.Results 3 cases were misdiagnosed as hemorrhoids, 1 polyps, and 2 tumor. Microscope mainly showed solid flake or gland bubble structure and epithelioid or spindle shape tumor cells, leading to misdiagnosis for anorectal poorly differentiated adenocarcinoma in 4 cases and low differentiated squamous carcinoma in 1 case; the general pathological misdiagnosis rate was 83.3%. Tmmunohistochemical specific antibody S-100 of melanoma, Melan-A, and HMB-45 were all positive. All the 6 patients were followed up. Case 1 to 5 survived 30, 42, 26, 46, and 52 months, and case 6 refused chemotherapy after operation and survived 28 months. Conclusion Primary anorectal malignant melanoma is rare and its histomorphology varies, so it is easily be misdiagnosed as other malignant tumors. The follow-up found that the mass, infiltration depth, having lymph node metastasis, and not being treated with chemotherapy, and biological treatment can significantly shorten survival time. Surgery is the main treatment at present. Chemotherapy combined biological treatment for terminally ill patients can improve the patients＇ prognosis but not very obviously.