Scimitar症候群を伴う左転移性肺腫瘍の1例

Left Metastatic Lung Tumor for a Patient with Scimitar Syndrome：Report of a Case

はじめに　部分肺静脈還流異常症（PAPVC）は肺静脈4本のうち1〜3本が体循環系に異常還流する疾患である．Scimitar症候群はその一亜型であり，右肺の低形成と右肺静脈の大部分が下大静脈へ還流するまれな先天性疾患である．PAPVCは無症状で経過し，術前検査などではじめて指摘されることも多い．PAPVCを伴う患者の肺切除では，非切除肺葉にPAPVCが存在すると右-左シャントが増大し重篤な右心不全をきたすことがあり1），還流静脈の修復が必要となる．われわれは，scimitar症候群を伴う左転移性肺腫瘍例に対して，血行再建術を施行した後に肺切除術を行ったので報告する．

Scimitar syndrome is a subtype of partial anomalous pulmonary venous connection, a rare congenital disorder associated with hypoplasia of the right lung. In addition to the difficulty of isolated lung ventilation, resection of the left lung is associated with the risk of developing right heart failure due to increased right-to-left shunts. We report a case of a left lung metastasis of a patient with scimitar syndrome. The patient, a 58-year-old male, was diagnosed with scimitar syndrome at the age of 26 but had never experienced any symptoms. He underwent chemoradiotherapy for mid-pharynx carcinoma and achieved complete response. During follow-up, a nodule appeared in the lower lobe of the left lung. Since right heart catheterization revealed a pulmonary blood flow/systemic blood flow ratio （Qp/Qs） ratio of 2.6, intra-cardiac blood flow was diverted prior to pulmonary resection. Stanford type A acute aortic dissection occurred intra-operatively, and total aortic arch replacement was performed. Three months later, partial pulmonary resection was performed with extracorporeal membrane oxygenation （ECMO） on standby. As oxygenation was maintained by placing a blocker in the left lower lobe bronchus and ventilating the left upper lobe with high frequency jet ventilation, the operation was completed without using ECMO. The nodule was pathologically diagnosed as metastasis of mid-pharynx carcinoma. He did not develop heart failure and was discharged on post operated day 15.