胸腔鏡下に摘出した縦隔内胸管囊胞の1例

Mediastinal Thoracic Duct Cyst Under Thoracoscopic Surgery：Report of a Case

はじめに　縦隔内に発生する囊胞は全縦隔腫瘍の10％程度を占めるとされ，気管支原性囊胞，食道囊胞，心膜囊胞，胸腺囊胞などの先天性囊胞が大部分を占める．われわれは，全縦隔腫瘍のうち0.05％ときわめてまれな囊胞性の縦隔腫瘍である胸管囊胞の1例を経験したので，若干の文献的考察を加えて報告する．

A 58-year-old woman was pointed out an abnormal electrocardiogram during a physical examination. A chest computed tomography （CT） scan revealed a 50-mm-sized cystic mass in the posterior mediastinum near the tracheal bifurcation. The mass exhibited growth during follow-up imaging, leading to a surgical resection. The tumor appeared as a smooth mass lesion with milky white and turbid internal content, suggestive of a chyle. The presence of a contiguous lymphatic duct and positive CD31 staining on histopathological examination confirmed the diagnosis of a thoracic duct cyst. Thoracic duct cysts have the risk of rapid growth and rupture, so in addition to checking for the appearance of new subjective symptoms, we suggest that surgical treatment should be considered if a tendency toward enlargement is observed as part of a shorter-than-usual imaging follow up. Careful identification and management of the thoracic duct flowing into and out of the tumor are important to prevent postoperative complications, especially chylothorax.