Tiny thymic carcinoma completely surrounded by thymic tissue. The possibility of de novo carcinoma.

We report a case of a 61-year-old man with a tiny thymic carcinoma completely surrounded by thymic tissue. First, a thoracoscopic resection of about two-thirds of the right inferior part of the thymus containing the tumor was performed to obtain the histological diagnosis. Frozen-section diagnosis at operation revealed a thymic carcinoma. Therefore we performed a median sternotomy and resected the remnant of the thymus. A tiny thymic carcinoma completely surrounded by thymic tissue is extremely rare. In this case, as the tumor was tiny and there was a homogeneous mass without a thymoma-like component, we concluded that this tumor was de novo.