出血合併により突然の前胸部圧迫感を生じた多房性胸腺嚢胞の1例

A case of multilocular thymic cyst presenting with sudden anterior chest pressure due to hemorrhage

多房性胸腺嚢胞（multilocular thymic cyst：MTC）は，1991年にSusterら^1）が18例をまとめ疾患概念を提唱した疾患である。先天性と考えられている単房性胸腺嚢胞と異なり，胸腺の炎症性変化に起因する後天性変化とされる。通常は無症状であり，画像所見は境界明瞭な多房性嚢胞性腫瘤を呈する。今回我々は，MTCに出血を伴い，突然の胸部圧迫感で発症し，非典型的な画像所見を呈した多房性胸腺嚢胞の1例を経験したので報告する。

A man in his 60s presented to another hospital complaining of sudden anterior chest pressure. CT and MRI revealed a 5-cm multilocular cystic lesion with hemorrhage in the anterior mediastinum. To control bleeding, embolization of the mediastinal branch of the left internal thoracic artery was performed, followed by thoracoscopic resection of the anterior mediastinal mass. Histopathological examination confirmed multilocular thymic cyst with hemorrhage. The patient was receiving anticoagulant therapy, which was considered to be related to the bleeding. Multilocular thymic cysts with massive hemorrhage may present with atypical clinical and imaging findings, making diagnosis challenging.