Cytogenetic Analysis Demonstrates Relatively Conserved Karyotypes When Taken from Multiple Areas of Individual Renal Cell Carcinomas
M Gupta, K Gill, P Dal Cin, MS Hirsch. Brigham and Womens Hospital, Boston, MA
Background: Renal cell carcinomas (RCCs) are a group of heterogeneous tumors with differences in gross, histologic and genetic features. Even within a single tumor, variable morphology and Fuhrman nuclear grade (FNG) can be seen. Although clinical stage is the strongest predictor of prognosis, RCC subtype and cytogenetic abnormalities also play a role in predicting clinical outcome. The aim of this study was to analyze if morphological (gross and microscopic) variation in RCCs reflect heterogeneity at the cytogenetic level.
Design: 57 consecutive, unselected RCCs were evaluated grossly at the time of surgery. From each tumor, 2 to 4 samples were collected for cytogenetic analysis (G Banding), and corresponding sections were submitted for routine histologic examination from the same areas. After processing was complete, cases were excluded if tumor cells did not grow in culture, and if only 1 karyotype or normal karyotypes were obtained. Comparisons were then made between histologic findings and karyotypic abnormalities.
Results: 23 cases with 2 or more corresponding morphologic and cytogenetic findings were available for final analysis. The majority of cases (18; 78%) were classified as clear cell (CC) RCC, and the remaining 5 cases were classified as papillary (4) and chromophobe (1) RCC. Two CC RCCs, 1 papillary RCC and the 1 chromophobe RCC demonstrated sarcomatoid differentiation. 14 cases (61%) had identical karyotypes and 9 cases (39%) had similar “base karyotypes” with a diagnostic finding consistent with a particular RCC subtype, but also showed additional losses, gains, or translocations in at least one of the other samples collected from a different area of the tumor. Of the latter 9 cases, the distribution of T stage was T1 (1), T2 (3), T3 (4) and T4 (1). Most of these cases contained cells with FNG III nuclei, and only 1 was associated with sarcomatoid differentiation. None of the cases demonstrated unique karyotypes from 2 or more cultures.
Conclusions: Although a heterogeneous group of tumors, the cytogenetic findings within a single RCC are relatively conserved, most (61%) with identical karyotypes. Those that were not identical still had a similar underlying diagnostic findings classic for a particular subtype of RCC, but also showed cytogenetic heterogeneity in the form of additional gains, losses or translocations. Further evaluation is necessary to determine if the latter findings, which were frequently associated with high grade and stage, have any independent prognostic value.
Category: Genitourinary (including renal tumors)
Wednesday, March 24, 2010 9:30 AM
Poster Session V # 88, Wednesday Morning