頸部多房性胸腺囊胞の1例

A case of cervical multilocular thymic cyst

はじめに

　頸部囊胞性腫瘤は日常診療において比較的よくみられるが，その鑑別は感染や良性疾患から悪性疾患まで多岐にわたる。しかし，身体所見や画像診断，術前の病理組織学的検索のみでは診断に至らないこともまれではない。今回われわれは，頸部囊胞性腫瘤に対して側頸囊胞やリンパ管囊腫を疑い手術を施行したが，手術病理にて頸部多房性胸腺囊胞（multilocular thymic cyst：MTC）と診断された症例を経験したため報告する。

　We report a rare case of a cervical multilocular thymic cyst. A 44-year-old man presented with a right neck mass since childhood. Imaging revealed a well-defined multilocular cystic lesion anterior to the sternocleidomastoid muscle and adjacent to major cervical vessels. The lesion was initially suspected to be a branchial cleft cyst or lymphangioma. Surgical excision was performed, and histopathology showed thymic tissue with Hassall's corpuscles, confirming the diagnosis. As cervical cystic lesions have diverse etiologies, including malignancies, accurate diagnosis can be difficult. Awareness of multilocular thymic cysts is important preoperatively to ensure proper differential diagnosis and avoid misinterpretation.