Benefits of a combined approach to sampling of renal neoplasms as demonstrated in a series of 351 cases.

Percutaneous radiofrequency ablation is increasingly used for curative treatment of primary cancers of the kidney. We reviewed our experience of percutaneous sampling performed under computed tomographic guidance with fine needle aspiration biopsy (FNAB) and core biopsy (CB), and we report on the complementary roles of these 2 techniques in a series of 351 consecutive patients undergoing radiofrequency ablation for renal neoplasms. Both FNAB and CB were obtained in 290 cases, of which 156 patients (54%) were positive for neoplasm in both specimens, and 27 (9%) were negative for tumor in both specimens. In 58 (20%) patients, the FNABs were positive, but the CBs were negative, and the reverse occurred in 11 patients (4%). When suspicious interpretations by FNAB and CB are included as positives in the calculations, both their complementary nature and the relative higher diagnostic yield of FNAB persisted. In 25 cases with FNABs positive for neoplasm, the CB allowed a more specific tumor classification. The 19 cases of FNAB which were read as negative/benign had corresponding CBs that were also negative/benign in 13 cases; yet, 6 were diagnostic of renal cell carcinoma not otherwise specified (1 case), renal cell carcinoma clear cell/conventional (4 cases), and non-Hodgkin lymphoma (1 case). These and additional findings illustrate the complementary value of the combination of the 2 biopsy methods for a reliable pretherapy morphologic confirmation of specific renal neoplasms. FNAB has relatively greater sensitivity and utility for onsite evaluation, whereas CB provides an additional sample for more specific subclassification and additional studies.