Diagnostic Biomarkers in Eosinophilic Renal Neoplasms

Incidental small renal masses identified on imaging are increasingly investigated via needle core or fine needle aspiration biopsies with limited material provided for rendering a diagnosis. Lesions with a prominent eosinophilic or oncocytic cell presence showing morphologic overlap between well-known eosinophilic neoplasms are challenging to diagnose. We review the range of known benign and malignant eosinophilic renal neoplasms and their immunoprofiles to elucidate a useful panel of stains that may assist the pathologist in making an accurate diagnosis.