Bilateral Parapelvic Cyst Misdiagnosed as Hydronephrosis.

A 36-year-old man visited our hospital with a suspected bilateral hydronephrosis that was detected during a routine check-up. Ultrasonography at the local clinic revealed a wide hypoechoic area in the center of both kidneys instead of a central echogenic complex (Fig. 1). Oliguria or abnormal laboratory values were not observed. On an axial view of the computed tomography with intravenous pyelogram (CT IVP) scan, low attenuated lesions with a cauliflower appearance were observed in the pelvises and calyces of both kidneys (Fig. 2A). No hydronephrosis or obstructive lesions in the urinary tract were observed on reconstructed intravenous pyelogram (IVP) image (Fig. 2B). A parapelvic cyst is a hypoechoic lesion located in the renal pelvis, which is often misdiagnosed as hydronephrosis because of its thin wall.12 In conclusion, CT IVP is a useful test for the differential diagnosis of parapelvic cysts.

FIG. 1

Ultrasonography image of left kidney. Septa between the parapelvic cysts are well defined on ultrasonographic exam.

FIG. 2

Abdominal computed tomography scan with intravenous pyelogram (CT IVP) image. (A) Axial view of the CT IVP scan with contrast showing low attenuated lesions involving both the renal pelvis and calyces. (B) Urinary tract obstruction was not observed on reconstructed CT IVP image.