Objective:

Collecting duct carcinoma (CDC) is a rare renal malignancy with high aggressiveness and poor prognosis. The aim of this paper is to improve the understanding of ultrasonic imaging of this kind of carcinoma.

Methods:

In this study

the ultrasonographic images of 5 patients with CDC were analyzed retrospectively

and those 5 patients all had their pathological results.

Results:

There were 5 CDC patients aged 58~80 years

including 4 males

and 1 female. The maximum diameter of the tumor ranged from 25 to 94 mm

mean (53.6024.86) mm. On conventional ultrasound images

2 cases of CDC presented hypoechoic mass without bulbous blood flow signal at the edge. Two patients showed full kidney shape without signs of mass effect. One patient presented local protuberance of renal parenchyma without abnormal blood flow signal. On CEUS images

CDC of 2 cases of mass and 1 case of local protrusion showed low enhancement of slow advance and fast retreat. The enhancement of mass was heterogeneous and the edge had no annular high enhancement. The other 2 cases of CDC with swollen renal morphology showed no obvious space occupying signs in the arterial stage

while in venous stage

patchy low-enhancement areas were found in the kidney with heterogeneous enhancement.

Conclusion:

CDC is a kind of hypo-vascular renal cell carcinoma with infiltrative growth

which is easy to be misdiagnosed. CEUS is helpful to show the features of microvascular perfusion between tumor and surrounding renal parenchyma

and to facilitate the detection and diagnosis of lesions.