肛管直肠恶性黑色素瘤临床病理特征分析

Clinicopathological Features of Anorectal Malignant Melanoma

目的研究肛管直肠恶性黑色素瘤的临床病理特征、手术方式、免疫组化特点及临床及病理误诊原因。方法回顾性分析11例肛管直肠原发性恶性黑色素瘤临床及病理资料,所有标本均进行HE及免疫组化染色,免疫组化采用Envision法。结果本组病例男3例,女8例,平均年龄58.3岁。主要症状便血、肛门坠胀感、肛门不适及肛门脱出物。病理大体外观:肿瘤多在齿状线附近呈结节状、息肉状、菜花状、溃疡型及平坦型,病理形态:上皮样细胞为主6例,梭形细胞为主4例,小细胞为主1例。免疫组化染色:Vimentin、S100、Melan-A在11例标本中均为阳性表达,HMB45在10例中阳性,其中1例为阴性。在这11例肛管直肠恶性黑色素瘤的病例中临床误诊率为81.8%(9/11),术前活检标本误诊率为27.27%(3/11),根治术后标本误诊率为9.1%(1/11)。结论肛管直肠恶性黑色素瘤是一种恶性程度极高、预后极差的恶性肿瘤。临床及病理极易误诊。免疫组化S100、HMB45、Melan-A/MART-1三者联合应用能提高恶性黑色素瘤病理诊断的准确性。发现肿瘤厚度与患者的预后密切相关。

Objective To study the clinicopathological features,surgical methods,immunohistochemical features,the clinical and pathological causes of misdiagnosis of anorectal malignant melanoma（AMM）.Methods A retrospective analysis was made to the clinical and pathological data of 11 cases（3 male and 8 female with the average age of 58.3 year old） with AMM;HE and immunohistochemical stain with Envision method were performed.Results The chief symptoms were hematochezia,sensation of rectal tenesmus,anal discomfort and prolapse;the pathological view with the naked eye indicated that the tumor were nodular,or polypoidal,or cauliflower-like,or ulcerative,or flat,located mostly along the dentate line;the histopathological view indicated 6 cases mainly with epithelioid cells,4 cases mainly with spindle cells and 1 case with small cells;the immunohistochemical stain indicated positive expression of Vimentin,S100 and Melan-A in the 11 cases while positive HMB45 in 10 cases and negative in 1 case;the clinical misdiagnosis was 81.8%（9/11）,the misdiagnosis of biopsy specimens before operation was 27.27（3/11）,and the misdiagnosis of specimens after radical resection was 9.1%（1/11）.Conclusions AMM is a tumor of high malignancy and worse prognosis,and it is often misdiagnosed in clinic and in pathological study;the combined application of S100,HMB45 and Melan-A/MART-1 in immunohistochemical study can raise the accuracy of pathological diagnosis of AMM;the thickness of the tumor is found to be in close relation with the prognosis of the patients.