[Loss of BRCA associated protein 1 expression in malignant mesothelioma and its diagnostic application].

Objective: To investigate the expression of BRCA-associated protein 1 (BAP1) in malignant mesothelioma, non-small cell lung cancer and carcinosarcoma, and its application in the differential diagnosis. Methods: Twenty-two cases of malignant mesothelioma including 17 epithelioid type, 2 sarcomatoid type and 3 biphasic type were collected.As the study control, 80 non-small cell lung cancers infringement pleural membrane(including 40 lung adenocarcinomas and 40 lung squamous cell carcinomas) and 15 carcinosarcomas were included. BAP1 expression was detected using immunohistochemical method. A differential diagnosis antibody panel, including calretinin, WT1, CK5/6, D2-40, CAM5.2, CEA, TTF1, Napsin A, p63 and p40 was tested in all cases. Results: All 80 cases of non-small cell lung cancer and 15 cases of carcinosarcoma were BAP1 positive. In contrast, 64% (14/22) of malignant mesotheliomas lost BAP1 expression (P<0.01). Addition of BAP1 to the mesothelioma marker panel, the diagnostic accuracy of malignant mesothelioma was enhanced to 93%. Focal expression of BAP1 in tumors suggested multiclonal evolution of mesothelioma. Conclusions: Loss of BAP1 expression helps to confirm the diagnosis of malignant mesothelioma whereas all non-small cell lung cancer expresses BAP1. It is therefore recommended that BAP1 can be used in conjunction with other immunohistochemical markers to improve the diagnostic accuracy of malignant mesothelioma.目的： 探讨BRCA相关蛋白1(BRCA associated protein 1，BAP1)在恶性间皮瘤、肺腺癌、肺鳞癌和癌肉瘤中表达情况及其在鉴别诊断中的作用。 方法： 选取恶性间皮瘤22例，其中上皮样型17例，肉瘤样型2例，双相型3例。另选取侵犯胸膜的非小细胞肺癌共80例(肺腺癌40例、肺鳞癌40例)和全身各部位癌肉瘤15例作为对照。应用免疫组织化学方法检测BAP1在各组病例的表达情况，并分析各组表达差异。同时所有病例均检测了常规用于间皮瘤鉴别诊断的抗体组合，包括calretinin、WT1、细胞角蛋白5/6、D2－40、CAM5.2、癌胚抗原、甲状腺转录因子1、Napsin A、p63和p40。 结果： 所有80例非小细胞肺癌和15例癌肉瘤均BAP1核表达阳性，而64%(14/22)恶性间皮瘤出现BAP1表达缺失，两者差异有统计学意义(P<0.01)。间皮瘤诊断标志物组合中，增加BAP1后，诊断恶性间皮瘤的诊断正确度达93%。BAP1灶性表达表明肿瘤细胞具有多克隆性。 结论： BAP1核表达缺失有助于鉴别恶性间皮瘤和非小细胞肺癌。因此推荐BAP1与其他间皮瘤抗体一起应用于恶性间皮瘤的诊断，提高恶性间皮瘤的诊断准确性。.