嫌色素性腎細胞癌における超音波断層像の検討

Abstract

根治的腎摘除術を施行し, 病理組織学的に嫌色素性腎細胞癌と診断された4例(男2例, 女2例, 43～66歳, 平均55.3歳)について, 超音波断層像を中心とした画像診断の特徴について検討した.血尿を主訴とした1例を除き, 他の3例は腹部超音波検査あるいはCTにて偶然発見された.患側は左側3例, 右側1例であった.病理組織学的TNM分類はpT1aN0M0が3例, pT2N0M0が1例であった.腫瘍内のエコーレベルはhyperechoic 3例, isoechoic 1例で, 内部パターンは4例とも均一であった.パワードプラ像では4例とも内部に血流を殆ど認めなかった.造影CTでは境界明瞭な低吸収域を呈し, 淡い造影効果を認めた.腫瘍内部は比較的均一であった.腫瘍径11cmの1例のみ変成に伴いやや不均一であったが, 出血・壊死像は認めなかった.MRIでは腫瘍内に腫瘍性分を認めなかった.腫瘍内部はT1強調像で境界明瞭な低信号を呈した.造影剤による早期濃染は認めなかったが, わずかに造影効果を認めた

Chromophobe cell renal carcinoma is an uncommon type of renal cell carcinoma, and the number of reported cases in Japan is small. The ultrasonographic (US) features of this rare tumor are not defined. We reviewed the imaging findings of four pathologically proven chromophobe cell renal carcinomas. US, color Doppler US (DUS), computed tomography (CT) and magnetic resonance imaging (MRI) were performed preoperatively. The internal echo patterns of the tumors were homogeneous in all cases, and the lesion usually was hyperechoic even if the tumor was large, although one tumor was isoechoic. DUS revealed no color flow in any tumor. Both CT and MRI showed a relatively homogeneous, hypovascular tumor. These tumors had characteristic US findings, probably because they had a uniform growth pattern of tumor cells and none of them had necrosis or hemorrhage. When US shows a homogenously hyperechoic and hypovascular tumor of the kidney, we should suspect chromophobe cell renal carcinoma.