Immunohistochemical phenotype and molecular pathological characteristics of metanephric adenoma.

To assess the clinicopathological, immunohistochemical and molecular features of metanephric adenoma (MA). Clinicopathologic data were obtained for 5 cases of MA with follow-up information. Specimens from these patients were stained by HE and immunohistochemistry for the detection of WT1, vimentin, S-100 protein, CK7, P504s, CD10 and renal cell carcinoma marker (RCC). Fluorescence in situ hybridization (FISH) was performed on 4 tumors. The patients included 1 male and 4 females, aged from 30 to 49 (mean=39) years. Tumor diameters ranged from 3 to 5.5 cm. Histologically, the tumors had tubular, papillary, or glomeruloid architectures, and were composed of cells with uniform and round nuclei, inconspicuous nucleoli, and high ratio of nucleus to cytoplasm. Nuclear polymorphism and mitotic figures were not observed. Immunohistochemically, they expressed WT1 (5/5), vimentin (5/5), S-100 (4/5), CK7 (2/5), P504s (2/5), and CD10 (1/5) and not RCC. FISH study was carried out on 4 metanephric adenoma cases, and no abnormalities were observed in chromosomes 3, 7, 17, and P16 gene of chromosomes 9. MA is an uncommon renal tumor. Its diagnosis depends on morphological, immunohistochemical and molecular features.