Coexisting undifferentiated thymic carcinoma and thymic carcinoid tumor

Thymic carcinoma is an unusual neoplasm, and the undifferentiated type is rare. Thymic carcinoid is also rare. This report describes a patient with coexisting undifferentiated thymic carcinoma and a carcinoid tumor. Both lesions were completely excised. The carcinoid cells showed argyrophilic granules by Grimelius' method and immunoreactivity against neuron-specific enolase, whereas the undifferentiated carcinoma cells were negative for argyrophilic stain and immunostaining against neuron-specific enolase.