for the Diagnosis of Renal Oncocytomas and Hybrid Oncocytic/Chromophobe Tumors

available at http://www.ncbi.nlm.nih.gov/pubmed/26386607 Editorial Comment: For decades diagnostic imaging of renal tumors has roughly relied on cross- sectional imaging and magnetic resonance imaging. An enhancing renal mass was considered suspicious for cancer and accordingly a treatment plan was devised. Once considered unuseful, nuclear imaging is now emerging as a means to differentiate clear cell renal cell carcinoma (RCC) from other subtypes, or as in this preliminary report as a possible way to differentiate benign lesions and those with low agressiveness, eg oncocytomas, chromophobe RCCs and hybrid oncocytic chromophobe tumors (HOCTs) from other RCCs. In this study 50 patients with a solid cT1 renal mass underwent imaging with 99m technetium- sestamibi single photon emission computerized tomography before surgical resection. Two nuclear medicine specialists blinded for pathology reports reviewed the preoperative scans and quantified maximum uptake of radiotracer in normal renal parenchyma and tumor. Relative radiotracer uptake was calculated as the ratio of tumor/parenchyma uptake, and the mean across 4 reads was calculated for each tumor. Two blinded pathologists reviewed the cases collaboratively and the consensual diagnosis served as the standard for comparison of the index test. Sestamibi correctly identified 5 of 6 oncocytomas and the 2 HOCTs for an overall sensitivity of 87.5% and specificity of 95.2% for diagnosis of oncocytoma/HOCT. Still 50% of chromophobe RCC and 1 of 8 oncocytoma plus HOCT cases were false-positive. This study is simple and well designed, and the methodology is adequate for the purposes of a diagnostic series. With caution ascribed to a preliminary report with as yet insufficient data to establish definitive conclusions, the idea is novel and if confirmed in a wide sample will signify an important advance in noninvasive diagnostic methods when RCC is suspected.