International Journal of Surgical Pathology 9(3):241-247, 2001 Metastatic Metanephric Adenoma with Foci of Papillary Carcinoma in a Child

We report an example of metastatic metanephric adenoma containing foci of papil-lary carcinoma in the primitive tumor arising in the left kidney of an 11-year-old girl. Histology revealed a monomorphous population of small cells with bland cytology arranged in pseudoglandular, tubular, papillary, and glomeruloid structures with fre-quent psammoma bodies. Intermixed there were foci of and small cavities lined by larger cells with eosinophilic cytoplasm and larger nuclei with small nucleoli. A re-gional lymph node contained metastatic deposits with the former histologic pattern. By immunohistochemistry the small cells were negative for carcinoembryonic anti-gen (CEA) and keratin 7 while these antibodies reacted positively in the larger cells. A fluorescent in-situ hybridization (FISH) study for chromosome 17 in imprints from the primitive tumor revealed 3 signals in about 10 % of the nuclei while the rest was disomic. Disaggregated cells from the metastatic lymph node consistently revealed 2 signals for chromosomes 7, 16, and 17. Histology of the primitive tumor resembled the epithelial component of the so-called metanephric adenofibroma while the metastatic lymph node exhibited histologic and FISH genomic features of metanephi