前立腺癌に続発したと考えられた射精管閉塞性精嚢嚢胞の1例

Abstract

79歳男.主訴は尿閉.直腸診にて前立腺部に表面平滑, 弾性軟で波動を伴う4横指の腫瘤を触知した.経直腸超音波検査(TRUS)にて前立腺から膀胱の後面に, 中隔構造を持ち不均一な低エコーを示す径7cmの嚢胞性腫瘤を認め, 造影CTでは嚢胞壁と中隅に造影効果を認め, MRIでは嚢胞壁はT1WI, T2WI共にlow intensity, 嚢胞内容はTIWIで尿よりややhigh intensity, T2WIで尿と同等のhigh intensityを示した.入院後, 37℃台の発熱を数回認め, CRP高値も持続したため, 嚢胞感染を疑いLVFX 300mg/日を投与し, 腰椎麻酔下に精管精嚢造影及びTRUSガイド下経会陰的前立腺針生検・嚢胞内容液穿刺吸引を施行した.針生検の結果, 前立腺左葉より中分化型腺癌が検出され, 前立腺癌(T2aN0M0)に合併した射精管閉塞性精嚢嚢胞と診断した.前立腺癌に対してbicalutamideとgoserelin acetateによるホルモン療法を開始した.嚢胞は穿刺吸引後, 著明に縮小し, 排尿困難も消失した.治療開始6ヵ月後の現在, 再燃なく, 嚢胞内溶液の再貯留も認めていない

We report a case of a seminal vesicle cyst supposed to be associated with prostate cancer in a 79-year-old Japanese man presenting with urinary retention. A fist-sized soft mass was palpated at the anterior wall of the rectum and serum prostate-specific antigen (PSA) was elevated to 59.8 ng/ml. Transrectal ultrasonography, computed tomography and magnetic resonance imaging revealed a retrovesical cystic mass measuring 7 cm in diameter and the absence of bilateral seminal vesicles. On vasography the lumen of the cystic lesion was visualized immediately, but the radiopaque fluid did not flow into the urethra. Transperineal prostate biopsy revealed moderately differentiated adenocarcinoma and puncture of the cyst revealed bloody fluid including sperm with a low PSA level. These findings strongly suggested that the mass was a seminal vesicle cyst caused by ejaculatory duct obstruction associated with prostate cancer. He has received endocrine therapy with goserelin acetate and bicalutamide for 6 months with no enlargement of the cystic lesion.