PROSPECTIVE ANALYSIS OF MULTIFOCALITY IN RENAL-CELL CARCINOMA - INFLUENCE OF HISTOLOGICAL PATTERN, GRADE, NUMBER, SIZE, VOLUME AND DEOXYRIBONUCLEIC-ACID PLOIDY

In an effort to characterize more fully multifocal renal cell carcinom a, 100 radical nephrectomy specimens with localized renal cell carcino ma were analyzed in a prospective fashion. Analysis of each specimen c onsisted of preoperative computerized tomography or magnetic resonance imaging, standard pathological examination with frozen section and 3 mm. step sectioning under magnification. Multifocal renal cell carcino ma was found in 16 specimens. Multifocal disease was suspected by preo perative imaging in 7 specimens (44%) and confirmed after standard pat hological investigation in 10 (63%). Papillary and mixed histological patterns occurred at a significantly increased rate in specimens with multifocal disease (p = 0.011). Other parameters, such as stage, tumor size and volume, histological grade and deoxyribonucleic acid ploidy were evaluated and did not correlate with the presence or extent of mu ltifocality. The number of secondary tumors per specimen varied from 1 to 50 (median 2) and were of higher grade in 3 (19%) and of lower gra de in 2 (12%) when compared with the predominant tumor. In conclusion, information from preoperative and to some degree intraoperative tests (except histological pattern) cannot reliably predict multifocality. The true risk for unknown multifocality in a surgical setting seems to be 6%, which roughly corresponds to the incidence of locally recurren t disease in published large institutional series.