ANALYSIS OF SOLID RENAL DYSPLASIA BY FLOW-CYTOMETRY - MALIGNANT POTENTIAL

Renal nodular blastema/nephroblastomatosis is a recognized precursor o f Wilms tumor. It also has been shown that nodular renal blastemata ar e seen in association with dysplastic renal parenchyma secondary to ob structive uropathy (i.e., ureteroceles or ectopic ureters). In an atte mpt to improve our understanding of the critical relationship between renal dysplasia and neoplasia, we performed flow cytometric evaluation on 16 paraffin-embedded specimens of dysplastic kidneys removed durin g the period 1984-1989. All nephrectomy specimens were associated with obstruction, either duplex collecting systems (10), ectopic ureters ( 2) or posterior urethral valves (2), or vesicoureteral reflux (2). One specimen was found to contain nodular renal blastema. No evidence of malignancy was found in any specimen. A specimen of normal kidney and two of Wilms tumor (favorable histology) were studied for comparison. Nuclear deoxyribonucleic acid (DNA) ploidy studies were performed on s ingle dissociated nuclei after deparaffinization and staining with pro pidium iodide. All dysplastic specimens, including the specimen with n odular renal blastema, demonstrated a diploid pattern of DNA as did th e specimens of normal renal tissue. The Wilms tumor specimens demonstr ated a diploid and a tetraploid pattern. In view of the fact that Wilm s tumor may demonstrate diploid DNA patterns on flow cytometry, the fi ndings of diploid patterns on all specimens of solid dysplasia militat e against but do not eliminate the possibility of malignant degenerati on.