Bosniak renal cyst classification : 12 years experience of a single center

Abstract

Objective To evaluate the clinical value of Bosniak renal cyst classification in the treatment of renal cyst disease.Methods The data of 509 patients,diagnosed with renal cystic disease from 2001 to 2012 in our institution,were retrospectively reviewed.Of those patients,there were 304 males and 205 females.The average age was 54 years (range 15-82 years).The average diameter of renal cysts was 6.8 cm (range,1.0-16.0 cm).According to Bosniak classification,there were 371 cases of category Ⅰ,60 cases of category Ⅱ,23 cases of category Ⅱ F,41 cases of category Ⅲ and 14 cases of category Ⅳ.Laparoscopic decortication of renal cysts was performed in 439 cases.Nephron sparing surgery was performed in 45 cases,including laparoscopic procedure in 20 cases.Radical nephrectomy was performed in 25 cases,including laparoscopic procedure in 5 cases.Results Benign lesions were diagnosed in 470 cases,including simple renal cyst in 448 cases,multilocular renal cyst in 15 cases,cystic nephroma in 3 cases,old hematoma in 2 cases,teratoma in 1 case and angiomyolipoma in 1 case.Malignant tumors were diagnosed in 39 cases,including clear cell carcinoma in 20 cases,multilocular renal cell carcinoma in 18 cases,and papillary renal cell carcinoma in 1 case.Based on Fuhrman nuclear grade classification,there were 28 cases (72％) of grade Ⅰ,9 cases (23％) of grade Ⅱ,2 cases (5％) of grade Ⅲ.In pathologic stage,T1 was diagnosed in 36 cases (92％),T2 was diagnosed in 3 cases (8％).The malignant rate was 1％ in Bosniak category Ⅰ (3/371),3％ in category Ⅱ (2/60),17％ in category ⅡF(4/23),44％ in category Ⅲ (18/41),and 86％ in category Ⅳ (12/14).Thirty-seven cases of malignancy were followed up for 3-144 months (median 53 months).All cases survived without recurrence or metastasis.Conclusions The Bosniak classification is helpful for diagnosis and management of renal cystic disease.There is a low malignant rate in category Ⅰ and Ⅱ cysts,but category Ⅲ and Ⅳ usually require surgical removal due to their high malignant rate.It should make effort to undertake laparoscopy and nephron-sparing surgery if technically feasible. Key words: Kidney diseases, cystic ; Bosniak classification ; Laparoscopes ; Nephron-sparing surgery