ロボット支援下に摘出しえた骨盤内神経鞘腫の1例

A case of pelvic schwannoma resected by robotic-assisted surgery

◆要旨：患者は68歳，男性．PSA高値を指摘され，当科を紹介受診し，生検にて前立腺癌を検出した．骨盤造影MRIにて右骨盤内に境界明瞭な腫瘍を認め，T2強調画像では辺縁高信号，内部は不均一な造影効果がみられた．発生部位，画像所見から神経鞘腫が考えられたが，本症例では骨盤内腫瘍がリンパ節転移など，前立腺癌由来であることを否定できなかったため，ロボット支援下に前立腺全摘術と骨盤内腫瘍摘出術を同時に施行した．病理組織学的所見では，骨盤内腫瘍に悪性像はなく，神経鞘腫と診断された．神経鞘腫はSchwann細胞から発生する腫瘍で，骨盤内後腹膜に発生する頻度は1％と極めて稀である．治療法は被膜を含めた外科的切除が第一選択であるが，できる限り発生神経を確認し，神経損傷をきたさないよう慎重な剝離が重要である．本症例のように狭小な骨盤深部の手術においては，ロボット支援下手術は低侵襲かつロボットアームの操作性，3D画像による視認性に優れ，有用なアプローチである.

The patient was a 62-year-old man who complained of high PSA level. Magnetic resonance imaging（MRI） showed a pelvic mass. T2-weighted images on pelvic contrast MRI showed a marginal high signal, with the interior showing a non-uniform contrast effect. The mass was believed to be a schwannoma considering the tumor site and imaging findings. However, because metastasis of prostate cancer could not be ruled out, tumorectomy was performed with robotic-assisted prostatectomy（RARP）. Histopathological findings showed no malignancy in the pelvic tumor, and the patient was diagnosed as having schwannoma. Schwannoma is a tumor generated from Schwann cells, and its frequency in the pelvic retroperitoneum is extremely rare, comprising approximately 1％ of pelvic retroperitoneal tumor. The first choice treatment is surgical resection including the capsule, but it is important to dissect the tumor carefully and preserve its originated nerve to avoid postoperative neurogenic disorder. In a surgery of narrow deep pelvis, as in the present case, robotic-assisted surgery is minimally invasive, offers excellent mobility of robotic instruments and visibility of 3D view, and is a useful approach.