We report a rare case of rosette-forming thymoma. Imprinting cytology specimens from the tumor showed tumor cells arranged in small clusters with radial fibrous bands on their surface. These cells also showed epithelial cells without cellular atypia. These cytological findings were helpful in distinguishing this tumor from a carcinoid tumor or thymic cancer. Although 2 years have passed since surgical resection, the patient is mostly well and has no tumor recurrence. To our knowledge, this is the first report on cytological figurs in a tumor.
