Radiological features of renal pelvic hemangioma: a case series

BACKGROUND: Renal pelvic hemangioma (RPH) is often misdiagnosed as renal pelvis cancer (RPC) due to its similarity in presentation, and there are few reports on the imaging findings of RPH. This study is aimed at improving the understanding of imaging findings specific for RPH by a retrospective analysis of the imaging findings of RPH. METHODS: RPH cases confirmed by pathology and with high-quality images were collected in the analysis. Nine cases of RPH were enrolled, of which 6 cases underwent ultrasound (US); 7 cases underwent computed tomography (CT), including 6 cases with an enhanced scan; and 2 cases underwent magnetic resonance imaging (MRI), including 1 case with an enhanced scan. All images of cases were analyzed and sorted independently by two senior attending radiologist blinded to the pathological results, according to the imaging indicators, such as the density and intensity on CT and MRI respectively. When the opinions between radiologists were inconsistent, images were re-evaluated together until a consensus was reached. RESULTS: Nine cases of RPH were collected from 5 males and 4 females, aged 16–70 years old, with a median age of 41 years. Five cases were located in the left kidney and 4 cases were located in the right kidney. The clinical symptoms mostly presented with hematuria. Nine cases demonstrated solitary masses, with 4 cases with blurred margins and 5 cases with well-defined margins. The size of the mass was about 1.5–8.0 cm, and the median size was 2.5 cm. The US showed mostly hypoechoic masses and color Doppler flow imaging (CDFI) showed minimal to no blood flow signal. Unenhanced CT scans showed mostly hypodensity and mostly mild continuous enhancement on an enhanced scan. The intensity of lesions was commonly heterogeneous on MRI due to hemorrhage and necrosis. One case showed mild continuous enhancement on an enhanced MRI scan. CONCLUSIONS: The imaging findings of RPH commonly present as a focal lesion with blurred or well-defined margins, mild and continuous enhancement, and no cachexia of the clinical symptoms. RPH should be differentiated from malignant tumors of the renal pelvis for treatment.