Unusual presentation of intraparenchymal renal artery aneurysm mimicking cystic renal cell carcinoma: a case report

Large renal artery aneurysm masquerading as renal cell carcinoma

Renal artery aneurysms (RAAs) are rare. Diagnosis is typically incidental with most cases asymptomatic and detected on routine imaging. Rarely large saccular RAAs may appear to extend to the neighbouring renal parenchyma. Differentiating these from renal tumours can be difficult and subsequent investigation with biopsy may result in fatal rupture. Our case describes an RAA arising from the right renal artery masquerading as renal cell carcinoma (RCC). Emphasis is placed upon thorough radiological evaluation ensuring that RAA is considered and excluded from the differential diagnosis prior to biopsy or surgical intervention. The role of multidisciplinary input is also emphasised.

Multimodality imaging review of focal renal lesions

Background

Focal lesions of the kidney comprise a spectrum of entities that can be broadly classified as malignant tumors, benign tumors, and non-neoplastic lesions. Malignant tumors include renal cell carcinoma subtypes, urothelial carcinoma, lymphoma, post-transplant lymphoproliferative disease, metastases to the kidney, and rare malignant lesions. Benign tumors include angiomyolipoma (fat-rich and fat-poor) and oncocytoma. Non-neoplastic lesions include infective, inflammatory, and vascular entities. Anatomical variants can also mimic focal masses.

Main body of the abstract

A range of imaging modalities are available to facilitate characterization; ultrasound (US), contrast-enhanced ultrasound (CEUS), computed tomography (CT), magnetic resonance (MR) imaging, and positron emission tomography (PET), each with their own strengths and limitations. Renal lesions are being detected with increasing frequency due to escalating imaging volumes. Accurate diagnosis is central to guiding clinical management and determining prognosis. Certain lesions require intervention, whereas others may be managed conservatively or deemed clinically insignificant. Challenging cases often benefit from a multimodality imaging approach combining the morphology, enhancement and metabolic features.

Short conclusion

Knowledge of the relevant clinical details and key imaging features is crucial for accurate characterization and differentiation of renal lesions.

Renal artery aneurysm mimicking renal calculus with hydronephrosis

A 51-year-old woman was found to have a left renal calculus with hydronephrosis. She underwent unsuccessful extracorporeal shock wave lithotripsy, leading to the recommendation that percutaneous lithotomy was necessary to remove the renal calculus. In view of the unusual shape of the calculus and absence of abnormalities in urine sediment, preoperative computed tomography and renal angiography were performed, which instead showed a calcified left renal artery aneurysm. Subsequent efforts to perform an aneurysmectomy also failed, eventually necessitating left nephrectomy. This case illustrates the pitfalls in the diagnosis of a renal artery aneurysm, which is a relatively common condition that may have unusual presentations. Hence, it is suggested that the possibility of a renal artery aneurysm be considered in the differential diagnosis when one detects a renal calculus with an unusual appearance. In addition, we propose that 3-dimensional reconstruction computed tomography be performed before considering surgical options for such renal calculi to rule out the possibility of a renal artery aneurysm.