METANEPHRIC ADENOMA OF THE KIDNEY - ULTRASTRUCTURAL, IMMUNOHISTOCHEMICAL AND LECTIN HISTOCHEMICAL-STUDIES

A case of metanephric adenoma, a rare benign tumor of the kidney is re ported, and the results of ultrastructural, immunohistochemical, and l ectin histochemical studies are presented. The patient was a 47 year o ld Japanese man presenting with a left renal tumor by ultrasonography. The nephrectomy material revealed a well-demarcated tumor with medull ary appearance, and on histological examination the tumor was composed of cuboidal cells forming regular small tubules with hyalinous stroma . Incomplete glomeruloid structures were formed in a few elongated tub ules composed of columnar cells. Metanephric blastema was not observed in the tumor or in the normal kidney. By electron microscope, the tum or cells were observed to be immature cells with microvilli at the api cal surfaces. The neoplastic tubules were surrounded by basal lamina. The tumor cells were immunoreactive for Leu 7, epithelial membrane ant igen, vimentin, and low molecular weight cytokeratin, and were weakly immunoreactive for S-100 protein. Peanut agglutinin, soybean agglutini n, and Dolichos biflorus agglutinin were bound to the apical surfaces of the tumor cells.