Renal artery aneurysm mimicking a solid parenchymal lesion

Giant Renal Artery Aneurysm With Hydronephrosis and Severe Atrophy of the Renal Parenchyma: Case Report and Literature Review

Background:

It is known that renal artery aneurysms may lead to hydronephrosis, but utter shrinking of the renal parenchyma due to a giant renal artery aneurysm has not yet been reported. This report is of an 88-year-old woman with resistant hypertension, hydronephrosis, and renal atrophy due to a giant saccular aneurysm of the left renal artery.

Case Report:

The patient presented with 2 weeks of worsening low back pain on the left side and resistant hypertension. The discovery of a left flank mass on physical examination, lead to the ultrasound detection of a para-aortic mass and a cyst-like partially septate structure replacing the left kidney. Thereafter, a contrast-enhanced computed tomography scan revealed a giant saccular aneurysm of the left renal artery causing severe hydronephrosis with severe parenchymal thinning. The extreme parenchymal atrophy of the left kidney made it an unlikely culprit of resistant hypertension, therefore the interventional radiologist considered that an endovascular attempt to re-establish the patency of the left renal artery would have scarcely produced any benefit. Given the advanced age of the patient, the vascular surgeon considered that risk of a nephrectomy outweighed the benefit, in agreement with the patient’s unwillingness to accept an invasive intervention. Therefore, she was discharged with blood pressure lowering and pain relief medication and was thereafter lost to follow-up.

Conclusion:

To our knowledge, this is the most severe kidney parenchymal shrinking in association with a renal artery aneurysm reported in the literature.

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.

Magnetic resonance imaging (MRI) of the renal sinus

This article presents methods to improve MR imaging approach of disorders of the renal sinus which are relatively uncommon and can be technically challenging. Multi-planar Single-shot T2-weighted (T2W) Fast Spin-Echo sequences are recommended to optimally assess anatomic relations of disease. Multi-planar 3D-T1W Gradient Recalled Echo imaging before and after Gadolinium administration depicts the presence and type of enhancement and relation to arterial, venous, and collecting system structures. To improve urographic phase MRI, concentrated Gadolinium in the collecting systems should be diluted. Diffusion-Weighted Imaging (DWI) should be performed before Gadolinium administration to minimize T2* effects. Renal sinus cysts are common but can occasionally be confused for dilated collecting system or calyceal diverticula, with the latter communicating with the collecting system and filling on urographic phase imaging. Vascular lesions (e.g., aneurysm, fistulas) may mimic cystic (or solid) lesions on non-enhanced MRI but can be suspected by noting similar signal intensity to the blood pool and diagnosis can be confirmed with MR angiogram/venogram. Multilocular cystic nephroma commonly extends to the renal sinus, however, to date are indistinguishable from cystic renal cell carcinoma (RCC). Solid hilar tumors are most commonly RCC and urothelial cell carcinoma (UCC). Hilar RCC are heterogeneous, hypervascular with epicenter in the renal cortex compared to UCC which are centered in the collecting system, homogeneously hypovascular, and show profound restricted diffusion. Diagnosis of renal sinus invasion in RCC is critically important as it is the most common imaging cause of pre-operative under-staging of disease. Fat is a normal component of the renal sinus; however, amount of sinus fat correlates with cardiovascular disease and is also seen in lipomatosis. Fat-containing hilar lesions include lipomas, angiomyolipomas, and less commonly other tumors which engulf sinus fat. Mesenchymal hilar tumors are rare. MR imaging diagnosis is generally not possible, although anatomic relations should be described to guide diagnosis by percutaneous biopsy or surgery.

Multiple visceral artery aneurysms

A 63-year-old woman patient was presented with 3 visceral artery aneurysms, which were identified accidentally at nuclear magnetic resonance imaging carried out because of small mass in the left adrenal gland, which was suspected by ultrasound. Computed tomography (CT) examination was indicated and showed fusiform aneurysm on splenic artery, saccular aneurysm of right renal artery, and saccular aneurysm of left segmental renal artery. Also, she experienced hypertension, cardiomyopathy, thyroid gland strum with normal hormone levels, osteoporosis, and rheumatoid arthritis. The patient was treated by open conventional surgery followed by end-to-end anastomosis reconstructions firstly of the right renal and then splenic artery. In 5 days, the patient was released from hospital in good condition. Control CT examination in 9 months did not show enlargement of remaining aneurysm. Histopathology confirmed just typical aneurysm degeneration based on atherosclerosis.