Adult mesoblastic nephroma with ciliated epithelium. A case report

A case of renal pelvic tumors occurring in a 44-year-old man is reported. T here were two polypoid renal pelvic tumors which consisted of, glandular an d stromal components. Some glands in the tumors had ciliated epithelium and were quite similar to the epididymal tubules. Other glands in the tumors r esembled the collecting duct or the mesonephric remnant seen in female geni talia. Immunohistochemistry and electron microscopy revealed smooth muscle differentiation of the stromal cells of these tumors. Some psammoma bodies were seen in the glands of the tumors. We diagnosed these tumors as adult m esoblastic nephroma (MN). The patient has been followed up for 14 months, s howing no evidence of recurrence. Differentiation of the tumors from angiom yolipoma, leiomyoma, and nephrogenic adenofibroma is discussed. Adult renal tumors that consist of epithelial and stromal components have been reporte d under various names. They constitute clinicopathologically different enti ties originating from pediatric MN. We suggest that these tumors should be termed "adult MN".