肺静脈を指標に切除辺縁を確保した胸腔鏡下左S3bc亜区域切除術

Thoracoscopic left S3bc subsegmentectomy with adequate surgical margins by using inter-segmental veins as landmarks

◆要旨：小型肺癌の縮小手術では，十分な切除辺縁を確保することが重要である．腫瘍の局在が同定可能な場合にはそれは容易であるが，同定不能例では工夫が必要である．症例は85歳，女性．膵臓癌術後のCTで左S³bに最大径2.3cm（充実径0.6cm）の結節を認め，原発性肺癌の疑いで切除辺縁を確保するため3D-CTを参考に4ポート下に胸腔鏡下左S³bc亜区域切除術を施行した．腫瘍の局在は同定不能なためV³b，V³c根部，V^1＋2aの分枝をそれぞれ尾側断端，深部断端，頭側断端に設定しS³bcを切除した．微小浸潤肺腺癌（最大径：1.5cm，浸潤径：0.4cm）の診断で，腫瘍は切除標本中央に位置し，切除辺縁は2.0cm以上を確保した．小型肺癌の縮小手術では，肺静脈を指標とした亜区域切除術も考慮可能な術式と考えられた．

　Securing a sufficient surgical margin is important in limited resections for small-sized lung cancers. Specific surgical strategies are necessary if the tumor cannot be localized during surgery. During a follow-up after pancreatic cancer treatment, an 85-year-old female patient was admitted with a suspicious lung cancer nodule with an overall diameter of 2.3cm（solid-part : 0.6cm）in the left S³b on CT. We planned thoracoscopic left S³bc subsegmentectomy under four-port access to secure an adequate surgical margin using the inter-segmental veins as the landmarks for the margin. The tumor could not be localized. The intra-operative frozen section identified no hilar lymph node metastases. The inter-segmental parenchyma between S³ and S⁴ was dissected along V³b（caudal-edge margin）. After the root of V³c（deep-edge margin）was dissected and divided, the branches of V^1＋2a（cranial-edge margin）were divided, and then A³bc was divided. B³bc was selectively closed with a slip-knot made with a monofilament thread after bilateral lung insufflation and divided with a stapler. S³bc was removed by dividing the peripheral parenchyma at the inter-segmental line along V^1＋2a. Histopathological examination diagnosed the tumor as a minimally invasive adenocarcinoma with a maximum diameter of 1.5cm（invasive size of 0.4cm）located in the center of the resected specimen. The surgical margin was more than 2.0 cm in all planes. Thoracoscopic anatomical subsegmentectomy using inter-segmental veins as a demarcation for sufficient surgical margin is considered to be feasible for small-sized lung cancer.