Touch Preps of Core Needle Biopsies from Renal Masses: 5 Years Retrospective Review and Interpretation Pitfalls
Sarah J Carroll, Elizabeth Hubbard, Stuart Van Meter, Laurentia Nodit. University of Tennessee Medical Center Knoxville, Knoxville, TN
Background: Due to increased use of radiologic studies, incidental renal cell carcinoma is more frequently detected. Minimally invasive techniques like percutaneous radiofrequency ablation are available for treatment of high risk patients and require documentation of presence of a neoplasm by CT-guided core needle biopsies. Touch preps of core needle biopsies are performed to evaluate adequacy of specimen collection and documentation of a malignant neoplasm allows interventional radiologists to perform radiofrequency ablation in a single procedure.
Design: We reviewed our electronic records from Jan. 2008-Apr. 2012 and identified 60 cases of CT-guided biopsies of renal masses on which intra-operative touch preparations were performed. Diff-Quik and rapid H&E stained smears were examined by cytopathologists blinded to the original interpretation or results of permanent sections and correlated to final biopsy diagnosis or follow-up where available.
Results: The series included 46 malignant renal neoplasms (renal cell carcinoma, oncocytic neoplasm, mixed epithelial and stromal tumor and urothelial carcinoma), 3 metastases from lung carcinomas, 2 angiomyolipomas and 12 benign inflammatory processes. Interpretation of intraoperative touch preps correctly identified the lesion as neoplastic or not in 47 of 60 cases (78.3%). Six cases were interpreted as neoplastic on touch preps, however, permanent sections of the core biopsy were benign (false positive rate of 10%) and 7 cases were called non-neoplastic on touch preps with a malignant neoplasm demonstrated on follow-up (false negative rate 11.6%). Angiomyolipoma, oncocytic change in renal tubular epithelium and infarcted parenchyma were the most frequent causes of false positive interpretation, whereas sparse cellularity and sampling were the main reasons for false negative results.
Conclusions: Touch preps of CT-guided core needle biopsies from renal lesions are imperfect tools in predicting malignant neoplasms. Knowledge of the limitations in interpretation of these samples allows the radiologist to take a more informed decision regarding performing radiofrequency ablation in a one versus two step procedure.
Monday, March 4, 2013 1:00 PM
Poster Session II # 98, Monday Afternoon