Imaging description

Fluid-filled structures (e.g., varices or parapelvic cysts) or solid hypoechoic masses (e.g., lymphomas or related conditions) in the renal hilum may simulate a dilated pelvicaliceal system at imaging and result in an erroneous diagnosis of hydronephrosis (Figures 46.1–46.3) [1–9].

Importance

Misidentification of intrarenal varices as hydronephrosis is potentially the most serious error, since attempted percutaneous nephrostomy tube placement could conceivably result in catastrophic bleeding. Misidentification of parapelvic cysts or solid hilar tumors as hydronephrosis could also lead to inappropriate treatment or a missed opportunity for earlier diagnosis and management of malignancy.

Typical clinical scenario

Renal hilar varices are typically manifestations of renal arteriovenous malformations, which may be congenital or acquired due to trauma, surgery, biopsy, malignancy, or inflammation [3]. Parapelvic cysts are found at 1.2 to 1.5% of autopsies, and may be congenital or acquired due to lymphatic blockage [10, 11]. Renal involvement by lymphoma or other malignancies of reduced echogenicity may occur at any age, but is commoner in adults.

Differential diagnosis

Hilar varices are easily recognized at ultrasound, provided Doppler images are acquired, since they contain internal flow. They are also easily recognized as tubular enhancing vascular structures at CT or MRI.