The Role of Fine Needle Aspiration Biopsy and Rapid Onsite Evaluation in the Diagnosis of Kidney Lesions.

Background: Although core needle biopsy is widely preferred for evaluating renal lesions, fine needle aspiration (FNA) combined with rapid on-site evaluation (ROSE) remains a valuable diagnostic method in selected cases. This study aims to assess the diagnostic efficacy of renal FNA and highlight the impact of ROSE on achieving definitive diagnoses.

Methods: This retrospective study included 273 patients who underwent ultrasound- or CT-guided FNA for renal lesions between 2010 and 2018 at Istanbul University-Cerrahpaşa, Cerrahpaşa Faculty of Medicine. Lesions were evaluated based on size, radiologic features, localization, ROSE status, and number of smears. Cytopathological results were categorized as nondiagnostic, limited, non-neoplastic, or neoplastic. Histopathological correlation was assessed in available cases. Statistical analyses were performed using SPSS v25.0, with p < 0.05 considered significant.

Results: Of the 273 cases, 218 (79.8%) yielded diagnostic results. Definitive diagnosis rates increased with lesion size and were significantly higher in solid (86.3%) and mixed (91.4%) lesions compared to cystic lesions (60%) (p = 0.001). ROSE was performed in 177 cases, significantly improving diagnostic yield compared to cases without ROSE (85.8% vs. 68.7%, p = 0.001). Histopathological follow-up was available in 119 cases, with an overall cytological-histological concordance of 84%, reaching 98% in cases with adequate material.

Conclusion: Renal FNA remains a reliable and accurate diagnostic method when combined with ROSE, especially in well-sampled cases. It aids in identifying both primary and metastatic tumors and can guide clinical decision-making, particularly when surgery is not feasible.