Application value of contrast-enhanced ultrasound in differential diagnosis of complex renal cysts and clear renal cell carcinoma with cystic change

Objective To investigate the value of contrast-enhanced ultrasound(CEUS) in differential diagnosis of complex renal cysts and clear renal cell carcinoma with cystic change(CRCCC). Methods The ultrasonographic datas of 82 lesions in 82 patients with complicated renal cysts or CRCCC confirmed by pathology were analyzed. The characteristics of conventional ultrasound and CEUS were observed and evaluated. The lesions were graded according to Bosniak classification criteria. Results Pathological examination showed that 36 cases were complicated renal cysts and 46 cases were CRCCC. Routine ultrasound showed there were 9 cases (25.0%) with cystic masses and 27 cases (75.0%) with solid and cystic masses in complex renal cysts, of which 14 cases (38.9%) could detect color flow signals. In CRCCC, 2 cases (4.3%) were with cystic masses and 44 cases (95.7%) were with solid and cystic masses, of which 33 cases (75.0%) could detect color flow signals. CEUS showed that only 18 cases (50.0%) of the complex renal cysts showed enhancement of cystic wall or septum, with equal or low enhancement at the peak, 9 cases (50.0%) accompanied by decrease of renal cortex, 35 cases (97.2%) had thin and regular cystic wall, no enhancement of cystic wall in all lesions, and 33 cases (91.7%) had septal thickness less than 1 mm. Forty-five cases (97.8%) of CRCCC showed enhancement of cystic wall or septum, 40 cases (88.9%) showed equal or high enhancement at peak, 30 cases (66.7%) were faster than the decrease of renal cortex, 37 cases (80.4%) showed uneven thickness of cystic wall, 24 cases (52.2%) showed enhancement of cystic wall nodules, and 28 cases (60.9%) showed uneven thickness of septum. After CEUS, 33 cases (91.7%) of complex renal cysts were classified as grade Ⅰ and Ⅱ, while 42 cases (91.3%) of CRCCC were classified as grade Ⅲ and Ⅳ. Conclusions The CEUS manifestations of complex renal cysts are different from those of CRCCC. The application of Bosniak criteria in CEUS is helpful for the differential diagnosis of complex renal cysts and CRCCC. Key words: Contrast-enhanced ultrasound; Complex renal cysts; Clear renal cell carcinoma with cystic change; Differential diagnosis