Cystic tumours of the kidney Bosniak IIF-III – occurrence and histopathology

113 Cystic tumours of the kidney Bosniak IIF-III – occurrence and histopathology Pitra T.1, Kalusova K.1, Travnicek I.1, Urge T.1, Hes O.2, Mirka H.3, Hora M.1 1 Medical School and Teaching Hospital Pilsen, Charles University, Dept. of Urology, Pilsen, Czech Republic, 2Medical School and Teaching Hospital Pilsen, Charles University, Dept. of Pathology, Pilsen, Czech Republic, 3Medical School and Teaching Hospital Pilsen, Charles University, Dept. of Radiology, Pilsen, Czech Republic INTRODUCTION & OBJECTIVES: Based on literature, for about 10% of renal tumours is presented by cystic tumours. The typical representatives are multilocular cystic renal cell carcinoma (MCRCC), mixed epithelial and stromal tumor (MEST) and cystic nephroma (CN). We can find secondary cystic modified tumours such as clear cell renal cell carcinoma (CRCC) and papillary renal cell carcinoma (PRCC). Cystic tumours of kidney are classified by Bosniak into the 5 groups. The purpose of this study was to describe occurrence and histopathology of cystic tumours of kidney - Bosniak IIF and Bosniak III. MATERIAL & METHODS: Using an institutional database, we retrospectively reviewed the data of patients, who underwent surgery for a tumor of kidney. RESULTS: Between 1/2010 and 12/2014 973 patients underwent surgery for renal tumor at our department. From these, 72 (7.4%) were identified as cystic lesion. According to Bosniak classification based on CT and MR imaging studies, 65 tumours were classified by Bosniak. 5 cases (7.7%) as Bosniak IIF, 29 cases (44.6%) as Bosniak III and 28 cases (43.1%) as Bosniak IV. Groups Bosniak I and II weren't included. The most common histologic finding in whole group was CRCC (50.8%) followed by PRCC (34.5%) and MCRCC (6.35%). In contrast, in the lesions identified preoperatively as Bosniak IIF, the most common histologic finding was PRCC (60%). 5 cases were identified as a simple cyst. CONCLUSIONS: Based on our institutional data Bosniak III cystic tumours present 44.6% of cystic tumours which underwent surgery. According to histological findings in our cohort, there is reasonable indication for surgical treatment of Bosniak IIF lesions, as more than 60% were presented as PRCC and 20% as CRCC. Eur Urol Suppl 2015; 14(6): e1275