Differential diagnosis of complex renal cysts based on lesion size along with the Bosniak renal cyst classification.
OBJECTIVE
To identify size criteria for complex cystic renal masses that can distinguish renal cell carcinoma from benign cysts supplementing the Bosniak classification.


METHODS
We reviewed the records of 97 patients who underwent surgery for complex cystic renal masses from January 2001 to April 2010. The pathological results were compared with the lesion sizes measured by preoperative computed tomography and other radiological features (contrast enhancement, irregularities of cyst walls and septa, and calcification) were also obtained for categorization according to the Bosniak renal cyst classification.


RESULTS
Malignancy was significantly associated with cyst size (>2 cm), male gender, and younger patient age (<50 years). According to the Bosniak classification, there was no category I cyst, and all 8 category II cysts were benign. However, 3 of 18 (17%) category IIF cysts, 21 of 39 (54%) category III cysts, and 29 of 32 (90%) category IV cysts were malignant. All category IIF cysts were benign in patients older than 50 years of age.


CONCLUSIONS
Many complex cystic renal masses smaller than 2 cm were benign. We suggest that lesion size should be taken into account when formulating treatment plans for complex cystic renal masses.
Department of Urology, Urological Science Institute, Yonsei University College of Medicine, Seoul, Korea.
Hyun Ho
HH
Han
Kyung Hwa
KH
Choi
Young Taik
YT
Oh
Seung Choul
SC
Yang
Woong Kyu
WK
Han
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002292:Carcinoma, Renal Cell / Q000175:diagnosis / Q000000981:diagnostic imaging; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D052177:Kidney Diseases, Cystic / Q000175:diagnosis* / Q000000981:diagnostic imaging; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D014057:Tomography, X-Ray Computed; D055815:Young Adult