An autopsy case of a cystic variant of thymic carcinoma mimicking a thymic cyst.

An autopsy case of thymic carcinoma is reported. The surgically excised cystic tumour from a 38-year-old Japanese male mimicked a thymic cyst pathologically. After a clinical course of 6 years, postmortem examination disclosed extensive metastases, including cystic lesions lined by benign-looking squamous epithelium. This evidence suggested that the present tumour was not of the specific variants of thymic carcinoma and not a thymic cyst with malignant transformation.