腎盂内にポリープ状の増殖形態を示したMixed epithelial and stromal tumorの1例

Abstract

68歳女.僧帽弁閉鎖不全症の精査加療中に腹部超音波検査で偶然右水腎症を発見された.諸検査により右腎盂腫瘍と診断し右腎尿管摘除術を施行した.腫瘍はポリープ状に腎髄質より上腎杯, 腎盂内に向かって発生していた.腫瘍の大きさは9×3×3cm, 割面は黄白色, 弾性硬, 表面平滑で, 内部には嚢胞を認めた.病理組織学的に腫瘍は間葉系組織と上皮組織から構成され, 基質にはコラーゲンの増生が著明であり, コラーゲンは束状あるいは渦状の走行を示し, その間に線維芽細胞や, 筋線維芽細胞と思われる紡錘型細胞が散在していた.腫瘍の辺縁部には一層の立方上皮からなる大小の嚢胞が存在し, 一部拡張した尿細管類似の腺管構造となっているところも認められた.構造細胞に異型性や核分裂像は認めなかった.これらの所見から良性mixed epithelial and stromal tumorと診断した.3年6ヵ月経過した現在, 再発の兆候は認めていない

A 68-year-old woman was found incidentally to have right hydronephrosis and a renal pelvic mass by abdominal ultrasonography. Radiographic examinations revealed a heterogeneous renal pelvic tumor, and right nephroureterectomy was performed. The tumor was well circumscribed yellow-whitish solid mass with scattered cysts. Histologically, the tumor was composed of both mesenchymal and epithelial components. The mesenchymal elements consisted of fibroblasts and smooth muscle cells, and the epithelial elements of cystic and tubular structures lined by cuboidal epithelium. Atypia and mitoses were not identified. The patient was free of recurrence 42 months postoperatively. Mixed epithelial and stromal tumor of the kidney is a recently recognized neoplasm that occurs almost exclusively in perimenopausal woman. Similar tumors have been reported previously under various names, including adult mesoblastic nephroma and cystic hamartoma of the renal pelvis. Histogenesis of the tumor is still controversial.