Metanephric Adenoma. Description of 11 Cases with a Demonstration ofCollagenous Spherules in One Case

Overview

Eleven cases of metanephric adenoma are reported. The tumors were selected out of 6500 tumorousand pseudotumorous lesions of the kidney in our registry. Female to male ratio was 1:1.2.The average age of the patients was 48.3 years, with a range of 13-79 years. The mean size of thetumors was 7.2 cm. The tumors were spherical in shape, whitish to yellowish in colour. Histologically,they were arranged in a mainly tubular pattern with short pseudopapillae. The tumorouscells were deeply eosinophilic to basophilic with predominantly round nuclei. Psammomatousbodies were numerous. Immunohistochemically, they reacted positively with antibodies againstcytokeratins, vimentin, and WT1. Ultrastructurally, the cytoplasm contained mitochondria, RER,and ribosomes. A collagenous spherulosis, identical with those in salivary gland and mammarytumors, was revealed in one case. The spherules were located mainly inside tubular structures.Ultrastructurally, they were composed of basement membrane-like material, which was surroundedby epithelial cells. Follow-up all of our patients was negative (if known) for 10 months to 4years.

Key words:
kidney - metanephric adenoma - collagenous spherules