Kidney Cancer Cytological Punctures in the Diagnosis of Renal Tumours: A Study on Accuracy and Reproducibility Intan P.E.D. Ku ¨ mmerlin a , Frank Smedts b , Fiebo J.W. ten Kate c , Thomas Horn d , Ferran Algaba e , Isabel Trias f , Hessel Wijkstra a , Jean J.M.C.H. de la Rosette a , M. Pilar Laguna a, * a Academic Medical Center, University of Amsterdam, Urology, Amsterdam, The Netherlands b Eastern Union of Hospitals, Pathology, Groningen, The Netherlands c Academic Medical Center, University of Amsterdam, Pathology, Amsterdam, The Netherlands d Herlev University Hospital, Pathology, Copenhagen, Denmark e Fundacio ´ Puigvert I.U.N.A., Pathology, Universitat Autonoma de Barcelona (UAB), Barcelona, Spain f Clı ´nica Plato ´ -Fundacio ´ Privada, Pathology, Barcelona, Spain european urology 55 (2009) 187–198 available at www.sciencedirect.com journal homepage: www.europeanurology.com Article info Article history: Accepted April 24, 2008 Published online ahead of print on May 7, 2008 Keywords: Kidney Renal neoplasm Classification Pathology Consensus Cytology Abstract Background: Fine needle aspiration (FNA) cytology is under consideration as an auxiliary pre- operative diagnostic technique in the diagnosis of renal masses. However, reports for FNA are contradictory with regard to diagnostic accuracy and applicability. Objective: To evaluate the diagnostic accuracy and reproducibility of FNA from renal masses. Design: FNAs performed in-bench (hematoxylin and eosin [H&E] stains) from 66 consecutive renal tumours (58 malignant and 8 benign tumours) were presented twice with a 6-mo interval to five pathologists with little experience in renal cytology. Pathologists were blinded for the results of the first round as well for the surgical specimen. The FNAs were stained for Papanicolaou and Giemsa. Measurements: Diagnostic accuracy, concordance between smears and surgical specimens, and the generalized kappa for interobserver/intraobserver agreement were calculated. Results and limitations: The number of nondiagnostic and nonconclusive cases ranged from 5–14% in the first and 3–8% in the second round. Overall accuracy varied between 73–89% and 71–91% for the first and second round, respectively. Sensitivity (72–97%) and positive predictive value (PPV) (93–100%) to classify a malignant tumour in both rounds was high. Sensitivity (25–100%) and PPV (28–100%) to classify a benign tumour was lower with a wide confidence interval. Overall con- cordance in subtyping ranged from 39–70% in the first, and from 52–74% in the second round. Interobserver agreement ranged from fair (k = 0.039) to substantial (k = 0.540) for the different subtypes. The intraobserver agreement (mean k = 0.357, CI 95% = 0.304–0.411) was moderate for all pathologists. The low number of benign tumours in this study precludes sound statements regarding the diagnostic accuracy of FNA to classify benignity. Conclusion: Despite the lack of experience in renal cytology, all pathologists showed a high diagnostic yield and good overall accuracy in distinguishing between malignant and benign tumours. Concordance in subtyping varied widely among pathologists and was reliable only for clear cell renal cell carcinoma (ccRCC). These results suggest that FNA may have a potential role in the diagnosis of renal tumours although its value in subtyping was limited in our setting. # 2008 European Association of Urology. Published by Elsevier B.V. All rights reserved. * Corresponding author. Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Tel.: +31 20 566 60 30; fax: +31 20 566 95 85. E-mail address: m.p.lagunapes@amc.uva.nl (M.P. Laguna). 0302-2838/$ – see back matter # 2008 European Association of Urology. Published by Elsevier B.V. All rights reserved. doi:10.1016/j.eururo.2008.04.072