[Recurrence of thymoma as pleural dissemination 23-years after surgery].

A 63-year-old female, who was noticed a chest mass approximately 4 cm in diameter on a chest X-ray, was admitted to our hospital. We thought that it was a benign chest wall tumor such as a neurogenic tumor by the findings of the chest computed tomography (CT). Resection of the tumor was performed. Neurogenic tumor was suspected by the frozen section. But it turned out to be a thymoma type AB in permanent preparation. Since she had undergone thymothymectomy 23-years ago, the tumor was considered to be a pleural recurrence of thymoma. We thoroughly checked the chest CT again, and detected another tumor at the right of the thoracic vertebra. Third surgery was performed and the tumor was resected. We experienced recurrence of thymoma as pleural dissemination 23-years after surgery. Thymomas are low-grade malignant tumor, but long-term clinical follow-up is necessary.