Abstract: PD52-04
Sources of Funding: None

Introduction

The proportion of oncocytic renal neoplasms diagnosed on renal mass biopsy (RMB) with discordant surgical pathology is unknown. We aimed to estimate the proportion confirmed as oncocytoma after surgery, the discordant pathologic findings, and indications leading to intervention.

Methods

A retrospective institutional cohort (2006-2015) identified patients with localized renal masses diagnosed with an oncocytic renal neoplasm on RMB suggestive of an oncocytoma. Concordance of surgical histopathology was evaluated for patients undergoing surgery. Additionally, a systematic review and meta-analysis of the literature (1997-July 1, 2016) was conducted to quantify all cases in the reported literature. Indications for intervention, when available, were assessed.

Results

A total of 31 (13.2%) of 234 core RMBs suggested oncocytoma, with 6 masses in 5 patients proceeding to surgery with none (0%) identified as oncocytoma, 3 (50%) diagnosed as renal cell carcinoma (RCC), and 3 (50%) diagnosed as other benign or indolent tumors. Nine additional studies were included in the meta-analysis for a total of 205 RMBs identifying oncocytic renal neoplasms with 46 (22.4%) proceeding to surgery. One additional study identified 2 neoplasms not captured by the primary RMB series for a total of 48 unique lesions included in the analysis. Surgical pathology showed oncocytoma (64.6%), chromophobe RCC (12.5%), other RCC (12.5%), hybrid oncocytic/chromphobe tumor (6.3%), and other benign lesions (4.2%). Positive predictive value of oncocytoma on RMB was 67% (95% confidence interval 34% to 94%) with significant heterogeneity between studies (I2=71.8%, p<0.01). Risk of bias was judged to be low for 4 of the 10 series.

Conclusions

Confidently diagnosing a localized renal mass as a benign lesion, such as an oncocytoma, has implications for the ultimate management strategy a patient will undergo. RMB was found to be unreliable in confidently diagnosing a localized renal mass as an oncocytoma with 1 in 4 found to be RCC on surgical pathology. Patients and physicians should be aware of the uncertainty in diagnosis when considering management strategies.

Funding

None