Aggressive renal angiomyolipoma extending into the renal vein and inferior vena cava - an uncommon entity

Multiple renal angiomyolipomas with asymptomatic nontraumatic pulmonary fat embolus: A case report

Although retroperitoneal bleeding and massive hematuria are potential complications of angiomyolipoma (AML), the pulmonary embolism as a presenting symptom is extremely rare. It is important to be aware that benign AMLs can present with pulmonary fat embolism.

Angiomyolipoma of the kidney-Clinicopathological analysis of 52 cases

The renal angiomyolipoma (AML) is a benign tumor characteristically composed of fat, smooth muscle tissue, and vessels. We collected AMLs from our nephrectomy database, reclassified them according to their histological appearance, recorded the demographic, clinical, and pathological parameters, and compared them with oncocytoma (RO) and renal cell carcinoma (RCC). Immunohistochemistry was ordered in 41 cases. In 2224 nephrectomies, we found 52 AMLs with a 53 mm median size. The mean age was 52.76. Forty-eight tumors were sporadic, while four were hereditary. The revision resulted in 31 classic, 13 leiomyoma-like, five lipoma-like, two epithelioid, and one AML with epithelial cysts. SMA was diffusely positive, except for the epithelioid type, while MelanA harbored stronger expression than HMB45. AML was more frequent in females and appeared ten and 7 years earlier than RO and RCC, respectively. The follow-up time was 7.42 years, and neither tumor-related death nor relapse occurred. AML is rare in nephrectomies and develops primarily in females in their 50s with an average size of 50-60 mm at the surgery. The histological appearance in order of frequency is classic, leiomyoma-like, lipoma-like, epithelioid, and cystic. The MelanA, HMB45, and SMA immunohistochemistry can support the light-microscopic findings.

Adult renal angiomyolipomas: A retrospective analysis of the histological subtypes and their clinicoradiological correlates

Background

Renal angiomyolipomas (AMLs) are rare, benign mesenchymal tumors of the kidney. Asian data on the prevalence of the subtypes of AMLs and their association with tuberous sclerosis are sparse prompting us to evaluate the clinicopathological characteristics of these tumors.

Materials and Methods

We included cases diagnosed from 2001 to 2021 extracting demographic details, clinical presentation, syndromic association with tuberous sclerosis, and preoperative clinicoradiological features from the electronic medical records.

Results

Ninety-five cases of adult renal AML were diagnosed among 2402 renal tumors, a prevalence of 3.95%. Forty tumors (42%) were detected incidentally; two patients had life-threatening retroperitoneal hemorrhage. Tuberous sclerosis complex (TSC) was associated with ten cases (10.5%). These patients were a decade younger than those in the non-TSC group (P = 0.008) and had bilateral, multiple, and larger tumors (P = 0.0009, 0.001, and 0.047, respectively). Microscopically, classic and epithelioid subtypes were seen in 87 (91.6%) and 8 cases (8.4%), respectively. Hemorrhage was more common in the epithelioid subtype (P = 0.13). HMB-45, melan-A, and smooth muscle actin immunohistochemistry were useful in cases which lacked the prototypical classic histology and for confirming a diagnosis of epithelioid AML.

Conclusions

The prevalence of renal AML in our series was four times higher, and the mean age at diagnosis was a decade earlier than that reported in Western literature but similar to data from two Asian countries. Similar studies from other countries will help ascertain if these differences in prevalence can be attributed to ethnic differences.

Radical nephrectomy and vena caval thrombectomy with the use of cardiopulmonary bypass and hypothermic circulatory arrest: Experience at a large tertiary institution

Objective:

This study aimed to review the experience at a large regional tertiary centre of open radical nephrectomy (RN) with vena caval thrombectomy with cardiopulmonary bypass (CPB) and hypothermic circulatory arrest (HCA) for the management of renal masses.

Method:

Data on patients with renal masses who had undergone RN and vena caval thrombectomy with CPB and HCA had been prospectively collected at two centres over a 19-year period (2000–2019). Twenty-three consecutive patients were identified and retrospectively analysed for operative and tumour characteristics and for postoperative outcome. Kaplan–Meier survival analysis was performed to compare patient outcomes based on tumour characteristics.

Results:

Median operating time was 358 minutes (interquartile range (IQR)=94 minutes), median bypass time was 117 minutes (IQR=28.5 minutes) and median circulation arrest time was 25 minutes (IQR=18.5 minutes). The median hospital length of stay was 11 days (IQR=5.3 days). Total complication rate was 52% ( n=12), consisting of four minor and eight major complications (Clavien–Dindo score >IIIa), including one intraoperative death. The overall five-year survival rate was 73% (11/15), with a median follow-up time of 53.1 months. Eleven (48%) patients were surgically cured, with a median follow-up time of 60.1 months (IQR=71.8 months). Disease recurrence was seen in eight (35%) patients, of whom four died. Patients who died survived for a median of 46.5 months. Median survival after the diagnosis of metastatic disease was seven months.

Conclusions:

We report the largest Australian cohort of RN with vena caval thrombectomy with CPB and HCA. We demonstrate outcomes comparable to major overseas centres, with an overall five-year survival rate of 73%. This suggests that even patients with extensive venal caval thrombus from renal masses can experience long-term survival benefit from RN and venal caval thrombectomy.

Level of evidence:

Level 3.

The Renal Vasculature: What the Radiologist Needs to Know

The physiologic role of the kidneys is dependent on the normal structure and functioning of the renal vasculature. Knowledge and understanding of the embryologic basis of the renal vasculature are necessary for the radiologist. Common anatomic variants involving the renal artery (supernumerary arteries and prehilar branching) and renal vein (supernumerary veins, delayed venous confluence, retroaortic or circumaortic vein) may affect procedures like renal transplantation, percutaneous biopsy, and aortic aneurysm repair. Venous compression syndromes (anterior and posterior nutcracker syndrome) can be symptomatic and can be diagnosed with a combination of radiologic features. Renal artery stenosis is commonly atherosclerotic and is diagnosed with Doppler US, CT angiography, or MR angiography. Fibromuscular dysplasia, the second most common cause of renal artery narrowing, has a characteristic string-of-beads appearance resulting from multifocal stenoses and dilatations. Manifestations of renal vasculitis differ depending on whether the affected vessels are large, medium, or small. Renal vascular injury is graded according to the American Association for the Surgery of Trauma (AAST) renal injury scale, which defines vascular injury and active bleeding in renal injuries. Both renal arteries and veins are affected by primary neoplasms or secondarily by neoplasms from adjacent structures. Differentiation between bland thrombus and tumor thrombus and the extent of involvement dictate management in malignancies, especially renal cell carcinoma. Aneurysms, pseudoaneurysms, arteriovenous malformations, and arteriovenous fistulas can affect renal vessels and can be diagnosed with specific imaging features. The radiologist has a critical role in identification of specific imaging characteristics and establishing the diagnosis in the varied pathologic conditions affecting the renal vasculature, which is critical for directing management. Thus, the renal vasculature should be an integral part of radiologists' checklist. ^©RSNA, 2021.

Aggressive Renal Angiomyolipoma in a Patient With Tuberous Sclerosis Resulting in Pulmonary Tumor Embolus and Pulmonary Infarction

Renal angiomyolipoma (AML) is the most commonly encountered mesenchymal tumor of the kidney which can present spontaneously or in association with tuberous sclerosis complex. Rarely, renal AMLs may demonstrate aggressive features such as renal vein invasion. This common entity and its uncommon complications are diagnosed based on physical examination and computed tomography results. Here we report imaging findings of a renal AML with renal vein and inferior vena cava invasion resulting in pulmonary tumor embolus and pulmonary infarction.

A rare case of renal angiomyolipoma involved both inferior vena cava and pulmonary arteries

Angiomyolipoma is a benign mesenchymal tumour, which rarely involve inferior vena cava (IVC) and pulmonary arteries. Here we reported a 41-year-old man, who presented symptoms of chronic pulmonary embolism. After multiple images evaluation, a large tumour with the same properties as the pulmonary embolism was found in the right kidney. One-staged surgery to remove both pulmonary embolism and right kidney was performed. Histological study showed the tumour and embolism as angiomyolipoma. The present study reported a rare case with renal angiomyolipoma and both IVC and pulmonary arteries involvements, which provided a good example for differential diagnosis in the emergency department and treating a rare type of chronic pulmonary embolism after renal angiomyolipoma.

Renal Angiomyolipoma With Caval Extension and Pulmonary Fat Embolism: A Case Report

Renal angiomyolipoma (AML) is a rare benign tumor of the kidney. Occasionally, it may extend into the renal vein or the inferior vena cava (IVC), but so far of pulmonary embolism in patients with renal AML was rarely reported. Here, a case of symptomatic pulmonary embolism secondary to AML that was placed IVC filter before the operation and then treated with radical nephrectomy is reported.This case highlights the rare possibility of renal vein and IVC involvement with symptomatic pulmonary fat embolism in renal AML, which may potentially result in fatal complications if not appropriately and cautiously managed with surgical intervention.

Ten uncommon and unusual variants of renal angiomyolipoma (AML): radiologic-pathologic correlation

Classic (triphasic) renal angiomyolipoma (AML) is currently classified as a neoplasm of perivascular epithelioid cells. For diagnosis of AML, the use of thin-section non-contrast enhanced CT (NECT) improves diagnostic accuracy; however, identifying gross fat within a very small AML is challenging and often better performed with chemical-shift MRI. Although the presence of gross intra-tumoural fat is essentially diagnostic of AML; co-existing intra-tumoural fat and calcification may represent renal cell carcinoma (RCC). Differentiating AML from retroperitoneal sarcoma can be difficult when AML is large; the feeding vessel and claw signs are suggestive imaging findings. AML can haemorrhage, with intra-tumoural aneurysm size >5 mm a more specific predictor of future haemorrhage than tumor size >4 cm. Diagnosis of AML in the setting of acute haemorrhage is complex; comparison studies or follow-up imaging may be required. Not all AML contain gross fat and imaging features of AML without visible fat overlap with RCC; however, homogeneity, hyperdensity at NECT, low T2-weighted signal intensity and, microscopic fat are suggestive features. Patients with tuberous sclerosis often demonstrate a combination of classic and minimal fat AML, but are also at a slightly increased risk for RCC and should be imaged cautiously. Several rare pathological variants of AML exist including AML with epithelial cysts and epithelioid AML, which have distinct imaging characteristics. Classic AML, although benign, can be locally invasive and the rare epithelioid AML can be frankly malignant. The purpose of this review is to highlight the imaging manifestations of 10 uncommon and unusual variants of AML using pathological correlation.

Comprehensive clinical and pathological analysis of aggressive renal epithelioid angiomyolipoma: report of three cases

Renal angiomyolipoma (AML) is recognized as a benign hamartomatous lesion arising in the kidney with no obvious malignant potential. However, epithelioid AML (EAML), a rare variant of AML, is potentially malignant, with aggressive clinical features. It can occur in patients with or without tuberous sclerosis. Because EAML may mimic renal cell carcinoma in imaging studies, differentiation of this tumor from renal cell carcinoma preoperatively is difficult. At times, the lesions may extend into the renal vein and inferior vena cava or metastasize to other organs such as the lung and liver. To clarify the biological nature of EAML, three specific cases that we encountered in clinical practice are analyzed and reported in detail.

Treatment of renal angiomyolipoma: surgery versus angioembolization

Renal angiomyolipoma (AML) is a benign mesenchymal tumour. AML often leads to haemorrhagic complications such as retroperitoneal haematoma. Treatment varies from case to case, ranging from minimally invasive approaches such as selective embolization of the renal artery to invasive wedge resection, partial nephrectomy or, in more severe cases, radical nephrectomy. Here we report a case of retroperitoneal haematoma secondary to AML, treated with conservative approach by super-selective embolization of the lower-pole segmental renal artery.