Renal oncocytoma: a challenging diagnosis.

Purpose Of Review: The aim of the review is to provide an update on the current and evolving approaches to diagnosing the challenging clinical entity of renal oncocytoma.

Recent Findings: Renal oncocytoma is being increasingly recognized among patients with renal masses, and it can be found in up to 50% of benign small renal masses (SRMs) less than 4 cm. Renal oncocytomas have benign clinical biology but distinguishing them from some of the other renal masses with more malignant potential can be challenging due to overlapping imaging, histologic, and immunophenotypic characteristics. Increasing integration of various imaging modalities, histologic characteristics, cytogenetics, and molecular and metabolic signatures is helping better define and characterize renal masses.

Summary: Evolving and complementary diagnostic approaches, including at the molecular level, are continuing to help refine the classification of renal tumors, with implications on their clinical behavior and ultimately clinical management.