尿閉を主訴とし, 肺小細胞癌に合併したLambert-Eaton筋無力症候群の1例

Abstract

65歳男性.尿閉状態で受診し内服治療を行うも排尿不可で尿道カテーテルを留置したが, 食欲不振で約1ヵ月間に10kgも体重が減少したため入院となった.膀胱鏡, 尿道・膀胱造影では異常は認めず, 膀胱内圧測定では尿意はあるが無収縮性膀胱を呈し, 胸腰椎MRIでも異常は認めなかった.また, 胸部X線やCTでは肺門部腫瘤陰影と縦隔リンパ節腫大が認められた.これらの所見より, 経尿道的前立腺切除術を施行し残尿率83%で導尿を継続したが, 術後まもなく便失禁, 上肢脱力感などの神経症状が出現し, 神経学的検査所見, 胸部画像所見から肺小細胞癌によるLambert-Eaton筋無力症候群を疑い, 左鎖骨上リンパ節および右肺門部腫瘤の生検を施行し, 肺小細胞癌と診断された.治療として全身化学療法を施行し, さらにその後, 放射線療法を行うことで排尿可能となり, 体重も増加し, 神経症状も改善した

A 65-year-old male was admitted with the chief complaint of voiding difficulty on 28 October, 2001. He was in the state of urinary retention. Urological investigation including cystosocopy, urethrocystography, and urodynamic study revealed an areflex-type bladder, according to the new International Continence Society (ICS) classification with no prostatic urethral obstruction. He was diagnosed with neurogenic bladder although the cause of detrusor areflex was unknown. Because all medication was ineffective, transurethral resection of prostate was performed on 11 January, 2002, but urinary retention could not be relieved. After operation, he complained of muscle weakness of upper extremities and poor control of bowels. He was diagnosed with Lambert-Eaton myasthenic syndrome associated with small cell lung carcinoma. His myasthenic symptoms, including autonomic symptoms were relieved after chemotherapy and radiation for small cell lung carcinoma.