Yoneda S, Marx A, Müller-Hermelink H K
Institute of Pathology, University of Würzburg, Germany.
Pathol Res Pract. 1999;195(8):555-63. doi: 10.1016/S0344-0338(99)80005-3.
A group of biphasic low-grade thymic epithelial tumors is presented that we suggest calling low-grade metaplastic carcinoma of the thymus [37]. Four of the patients were men, their age ranging from 44 to 71 years. Three tumors invaded mediastinal fat or pleura. No metastases were present. Histologically, the tumors showed a biphasic pattern with solid carcinomatous areas merging with a spindle cell component. Only few lymphocytes were present. Cytological atypia and mitotic activity were variable in the solid areas, but low in the spindle cell component. The tumors showed expression of cytokeratin, vimentin and/or epithelial membrane antigen (EMA), both in the carcinomatous and in spindle cell components. In two cases, actin expression was also present in both components. In one case, chromogranin, S100 protein, glial fibrillary acidic protein, and neuron specific enolase were expressed in a minority of cells of both components. None of the patients had myasthenia gravis. All patients are alive without distant metastasis, but meanwhile one patient suffers from local recurrence. We conclude that metaplastic carcinoma of the thymus is a clinicopathological entity that is probably distinct from the recently described "thymoma with pseudosarcomatous stroma", and should be distinguished from the usually benign medullary thymomas and the highly aggressive carcinosarcomas and sarcomatoid carcinomas.
本文报告了一组双相性低度胸腺上皮性肿瘤，我们建议将其称为胸腺低度化生癌[37]。患者中4例为男性，年龄在44至71岁之间。3例肿瘤侵犯纵隔脂肪或胸膜。均无转移。组织学上，肿瘤呈双相性模式，实性癌区与梭形细胞成分融合。仅见少量淋巴细胞。实性区域的细胞异型性和有丝分裂活性各不相同，但梭形细胞成分中较低。肿瘤在癌性成分和梭形细胞成分中均显示细胞角蛋白、波形蛋白和/或上皮膜抗原（EMA）表达。2例中，肌动蛋白在两种成分中也均有表达。1例中，嗜铬粒蛋白、S100蛋白、胶质纤维酸性蛋白和神经元特异性烯醇化酶在两种成分的少数细胞中表达。所有患者均无重症肌无力。所有患者均存活且无远处转移，但有1例患者出现局部复发。我们得出结论，胸腺化生癌是一种临床病理实体，可能与最近描述的“伴有假肉瘤性间质的胸腺瘤”不同，应与通常良性的髓质型胸腺瘤以及高度侵袭性的癌肉瘤和肉瘤样癌相鉴别。
