Descriptive report of complex cystic renal mass fluid cytology: a cross-sectional analysis.

Abstract

Background: During surgical extirpation of cystic renal masses, surgeons attempt to avoid cyst rupture due to the theoretical risk of tumor seeding. Whether the concern regarding tumor seeding is warranted is debatable. Our objective was to evaluate the presence of malignant cells in the fluid of complex renal cysts.

Methods: This was a cross-sectional analysis of adult patients undergoing radical or partial nephrectomy to address a cystic renal mass. Patients undergoing a partial or radical nephrectomy by open or robotic approach for a clinically localized (< cT2N0M0) cystic renal mass were included. Following excision, fluid from the mass was aspirated and sent for cytologic analysis. Cyst fluid was prepared by processing up to 50 mL into a PreservCyt^® vial on a ThinPrep^® 2000 or ThinPrep^® 5000 processor using standard protocols, resulting in a pap-stained ThinPrep glass slide. The second half of the fluid was processed into a cellblock using a plasma/thrombin process resulting in a Formalin-Fixed Paraffin-Embedded (FFPE) block cut to produce a hematoxylin and eosin (H&E)-stained slide. Both the pap-stained and H&E slides were evaluated for malignant cells by a cytotechnologist and pathologist.

Results: Twenty-three patients underwent resection of 24 cystic tumors including 17 (73.9%) males and 6 (26.1%) females. The median patient age was 58 years [interquartile range (IQR), 43-68 years]. The median tumor diameter was 3.7 cm (IQR, 3.2-6.1 cm). Most patients underwent robotic partial nephrectomy (n=19, 83%). Renal cyst cytology was benign in 46% (n=11), atypical in 29% (n=7), suspicious in 8% (n=2), positive for neoplasm in 4% (n=1), and positive for malignancy in 4% (n=1). Clear cell renal cell carcinoma was the most common histologic subtype (n=17, 71%).

Conclusions: Based on routine cytologic analysis, there is no clear pattern with the presence or absence of malignant cells in the fluid of complex renal cysts. More sophisticated testing may provide insight into the malignant potential of renal cyst fluid.