多中心性発生と考えられた多発胸腺腫の1例

Synchronous Multiple Thymoma Suggested to be Multi-centric Origin：Report of a Case

はじめに　胸腺腫の多発は比較的まれな病態であり，発生メカニズムについては議論のあるところである．われわれは，多中心性発生と考えられた同時多発胸腺腫の1例を経験したので報告する．

A 57 years-old man was referred to our hospital because of an abnormal shadow in the left hilum on a screening chest X-ray. His physical exam and laboratory data were not notable. Chest computed tomography （CT） showed two nodules one of which is cystic in the anterior mediastinum, and positron emission tomography with 18F-fluoro-2-deoxy-D-glucose showed relatively mild uptake in both tumors. We suspected mucosa associated lymphoid tissue （MALT） lymphoma or multiple thymomas, and performed thoracoscopic thymo-thymectomy. The operative findings showed two separated tumors in the thymus. Histopathological examination revealed that both tumors were type B1 thymomas of 35 mm and 40 mm in size. Since both tumors were encapsulated without continuity, multi-centric origin was suggested.