Ningbo Diagnostic Pathology Center, Huan Cheng Bei Lu, Ningbo, China.
Int J Surg Pathol. 2022 Aug;30(5):564-568. doi: 10.1177/10668969211070484. Epub 2021 Dec 31.
The correlation of histogenesis between metaplastic thymoma and thymic sarcomatoid carcinoma is unclear. We report a case of metaplastic thymoma transformed into high-grade sarcomatoid carcinoma. A 64 × 54 × 32 mm anterior mediastinal mass in a 61-year-old woman microscopically consisted mainly of classic metaplastic thymoma, with the center dominated by high-grade sarcomatoid carcinoma. In some areas, both epithelial and spindle cell components of the metaplastic thymoma showed increased cellular atypia, mitotic activity, and focal necrosis and gradually transformed into the polygonal/pleomorphic and spindle cell components of sarcomatoid carcinoma. Immunohistochemically, the characteristics of the polygonal/pleomorphic sarcomatoid cells were similar to those of the epithelial component of metaplastic thymoma, while the spindle sarcomatoid cells were more similar to the spindle cells component of metaplastic thymoma. The Ki-67 index was less than 5% in the metaplastic thymoma areas but up to 70% in the sarcomatoid carcinoma area. Radical operation and postoperative radiotherapy were performed. Multifocal relapses at the pleura occurred 13 months after surgery.
胸腺瘤的化生与胸腺癌的相关性尚不清楚。我们报告了一例由胸腺瘤化生为高级别肉瘤样癌的病例。一名 61 岁女性的前纵隔有一个 64×54×32mm 的肿块，显微镜下主要由经典的胸腺瘤化生组成，中心以高级别肉瘤样癌为主。在某些区域，胸腺瘤的上皮和梭形细胞成分均表现出细胞异型性增加、有丝分裂活性和局灶性坏死，并逐渐转化为肉瘤样癌的多边形/多形性和梭形细胞成分。免疫组化染色显示，多边形/多形性肉瘤样细胞的特征与胸腺瘤的上皮成分相似，而梭形肉瘤样细胞则更类似于胸腺瘤的梭形细胞成分。胸腺瘤区 Ki-67 指数小于 5%，而肉瘤样癌区高达 70%。行根治性手术和术后放疗。术后 13 个月胸膜出现多处复发。
