SIMULTANEOUS CHROMOSOME-7 AND CHROMOSOME-17 GAIN AND SEX-CHROMOSOME LOSS PROVIDE EVIDENCE THAT RENAL METANEPHRIC ADENOMA IS RELATED TO PAPILLARY RENAL-CELL CARCINOMA

Purpose: Metanephric adenoma has recently been recognized as a unique renal tumor characterized by an unusual degree of cellular differentia tion and maturation. We recently studied metanephric adenoma using met aphase analysis and observed concomitant chromosome Y loss and chromos ome 7 and 17 gain. To determine if these chromosomal anomalies are con sistently present in renal metanephric adenoma, we studied all 11 tumo rs in the pathology tissue registry at our institution using fluoresce nce in situ hybridization (FISH). Materials and Methods. FISH, using d eoxyribonucleic acid probes for chromosomes 1, 7, 8, 17; X and Y, was performed in isolated nuclei from 11 paraffin embedded renal metanephr ic adenoma specimens. Results: Of the 11 tumors (73%) 8 demonstrated c hromosome 7 and 17 gain by FISH, and the remaining 3 were found to hav e an apparently normal chromosomal content. Of the 8 tumors (75%) from men showed 6 chromosome 7 and 17 gain with Y chromosome loss. Of the 3 tumors (33%) from women 1 had chromosome 7 and 17 gain with X chromo some loss, while 1 had chromosome 7 and 17 gain without sex chromosome aneusomy. Metaphase analysis performed on 2 tumors revealed chromosom e 7 and 17 gain and Y chromosome loss in 1, and no apparent chromosome anomaly in the other, confirming the results of FISH analysis. Conclu sions: FISH analysis of renal metanephric adenoma identified frequent chromosome 7 and 17 gain and sex chromosome loss. These results are co nsistent with a clonal neoplastic disorder in which chromosomes 7, 17, X and Y are likely to be involved in the pathogenesis of this tumor. These characteristic chromosomal alterations have also been observed i n papillary renal cell adenoma and papillary renal cell carcinoma, pro viding evidence that these tumors may be related.