Rapid On-Site Evaluation of Core Needle Biopsy of Renal Masses Using Touch Preparation: An Institutional Experience

Summary: Introduction: Incidental detection of clinical stage 1 renal masses by imaging has been increasing steadily. The role of renal mass biopsy, once considered of limited use, has been revisited as 20% of clinical stage 1 renal masses may represent benign disease and could benefit from less aggressive management. The aim of the study is to determine the performance of the rapid on-site evaluation of touch preparation (TP) of core needle biopsy (CNB) relative to the final core needle biopsy (CNB) diagnosis at our institution. Materials and Methods: Routine cytologic-histologic correlation (CHC) was performed using the results of the TP diagnostic category against the final CNB diagnosis. TP diagnostic categories included: nondiagnostic, negative, indeterminate (atypical and neoplasm of uncertain malignant potential) and positive (suspicious for malignancy and malignant). The correlations were categorized as Agree, Disagree-Minor (DSMN), Disagree-Major (DSMJ). Table 1 demonstrates the rationale for correlation outcome designation. Results: Over a period of 6 months, 72 cases of CNB with TP were available. Agreement between TP and CNB diagnosis was reached in 48 (67%) cases while DSMN was present in 18 (25%) cases. and DSMJ in 6 (8%) cases. Table 2 illustrates the correlation results of TP against CNB diagnosis. Three of 4 angiomyolipomas were interpreted as malignant or suspicious for malignancy and only 1 of 4 oncocytic neoplasms was correctly identified as indeterminate. DSMJ resulted from equal number of overcalls /undercalls. Conclusions: Our study shows that TP of CNB is an appropriate tool for the evaluation of renal masses. While TP correctly identified the majority of malignant tumors, oncocytic neoplasms and angiomyolipomas were the most common source of DSMN. DSMJ was associated with overcall of renal tubular sheets with or without oncocytic changes or undercall in paucicellular samples and predominantly cystic tumors. DSMN amd DSMJ cases identify areas for education and improvement.