Analysis of the histogenesis of thymoma

点击翻译按钮获取中文摘要

We examined thymomas immunohitochemically. Type A thymoma (14 cases) were composed solely of pCK+/EMA-/VM)-/CDN-1+ shout spindle epithelial cells. Thy nor TCDM were not found at all. Metaplastic thymoma (1 case) was found to be mosaic of two different components, pCK+/VM-/EMA-/CDN-1+ tumor cells of type A thymoma and pCK-/VM+/EMA+/CDN-1- fibroblastoid metaplastic epithelial cells (FMECs). In the majority of type AB thymoma (14 of 19 cases), type A-like areas were composed of FMECs. In contrast, type A-like areas of remaining 5 cases were composed of type A thymoma cells. These findings indicate that there are two different subtypes in type AB thymoma, metaplastic type AB thymoma and conventional type AB thymoma. The presence of a considerable numbers of TCDM in types B thymomas and β5t-immunoreactivity of tumor cells indicates that type B thymomas are basically tumor of c-TECs. We also found that there are two subtypes of type B3 thymoma, the differentiated subtype containing TCDM and the anaplastic subutype lucking TCDM, although clinical between them remains unclear. We also found that type B3 thymoma are able to be distinguished from thymic carcinoma by proper use of markers such as thy/TCDM, β5t, c-Kit and/or CD5