LAUSR

There are a variety of benign renal tumors that can be identified on biopsy material (either fine ‐ needle aspiration [FNA] or core needle biopsy). Renal cysts are the most common benign renal lesion and need to be distinguished from cystic renal tumors including multi-locular cystic renal neoplasms of low malignant potential. Fortunately, the vast majority of renal cysts are diagnosed by radiology because biopsy is unreliable with a sensitivity of approximately 10% for purely cystic renal cell carcinoma. 1 Oncocytoma, angiomyolipoma (AML), and papillary adenoma have been the most common solid benign renal tumors, and criteria for their diagnosis are well described. In the most recent World Health Organization classification of renal tumors, 2 clear cell papillary renal cell carcinoma has been renamed clear cell papillary renal cell tumor (CCPRCT) to better reflect that fact that, at least to date, this tumor is also benign. How then should cytologists diagnose specimens in which they may be considering these diagnoses? The