Abstract
A 65-year-old woman underwent tumor resection on the suspicion of an invasive thymoma of Masaoka stage IV. The pathological and immunohistochemical findings revealed that this tumor had components of large cell neuroendocrine carcinoma and small cell carcinoma, and it was finally diagnosed as poorly differentiated neuroendocrine carcinoma of the thymus. Although we performed complete resection, a distant relapse was detected 8 months after surgery. Poorly differentiated neuroendocrine carcinomas of the thymus are very rare. Because these tumors have a poor prognosis, it is necessary to document and study cases of this tumor to understand its pathology and suitable treatment.
