Congenital Mesoblastic Nephromaに類似した成人腎過誤腫の1例

Abstract

A 35-year old man was hospitalized for left flank pain. IVP showed left non-visualizing kidney with multiple renal calculi. Selective renal arteriogram revealed avascular mass in the left upper pole. The upper calyx was irregularly distorted. Left nephrectomy was carried out. Grossly, the upper pole was replaced by whitish, firm and homogeneous tumor, which was 7 X 7 cm in diameter and protruded into the upper calyx. Histologically, the tumor was composed of both epithelial and mesenchymal components. The epithelial elements consisted of cysts and tubules, and the mesenchymal elements of loosely textured fibroblasts and smooth muscle cells. Other elements could not be identified. This case was diagnosed as renal hamartoma histologically resembling congenital mesoblastic nephroma of infancy. Congenital mesoblastic nephroma is rare in adults. Continued maturation may finally transform it either to benign mixed tumor as in our case or fibromatous tumor if stroma matures dominantly.