Clinical behavior and management of three types of renal angiomyolipomas

Comprehensive Insights Into Renal Perivascular Epithelioid Cell Neoplasms: From Molecular Mechanisms to Clinical Practice

Perivascular epithelioid cell neoplasms (PEComas) are a rare category of mesenchymal tissue tumors, manifesting across various tissues and organs such as the kidneys, liver, lungs, pancreas, uterus, ovaries, and gastrointestinal tract. They predominantly affect females more than males. PEComas characteristically express both melanocytic and smooth muscle markers, making immunohistochemistry vital for their diagnosis. Renal angiomyolipoma (AML) represents a common variant of PEComas, typically marked by favorable prognoses. Nonetheless, only a small fraction of subtypes, especially epithelioid AML, possess the capacity to be malignant. Renal PEComas usually appear as asymptomatic masses accompanied by vague imaging characteristics. The main methods for diagnosis are histopathological analysis and the application of immunohistochemical stains. Presently, a uniform treatment plan for renal PEComas is absent. Strategies for management include active surveillance, selective arterial embolization, surgical procedures, and drug-based treatments. The focus of this review is on renal PEComas, shedding light on their pathogenesis, pathological characteristics, clinical presentations, diagnosis, and treatment modalities, and incorporating a clinical case study.

Clinical practice recommendations for kidney involvement in tuberous sclerosis complex: a consensus statement by the ERKNet Working Group for Autosomal Dominant Structural Kidney Disorders and the ERA Genes & Kidney Working Group

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by the presence of proliferative lesions throughout the body. Management of TSC is challenging because patients have a multifaceted systemic illness with prominent neurological and developmental impact as well as potentially severe kidney, heart and lung phenotypes; however, every organ system can be involved. Adequate care for patients with TSC requires a coordinated effort involving a multidisciplinary team of clinicians and support staff. This clinical practice recommendation was developed by nephrologists, urologists, paediatric radiologists, interventional radiologists, geneticists, pathologists, and patient and family group representatives, with a focus on TSC-associated kidney manifestations. Careful monitoring of kidney function and assessment of kidney structural lesions by imaging enable early interventions that can preserve kidney function through targeted approaches. Here, we summarize the current evidence and present recommendations for the multidisciplinary management of kidney involvement in TSC.

Natural History and Management of Ultrasound-detected Small Renal Angiomyolipoma

Background

Recent advances in imaging methods increased the incidental detection of small renal angiomyolipoma (AML). However, guidelines for managing small AML are lacking, and decisions about imaging frequency and timing of intervention are made on an individual basis. This study aims to investigate the clinical behavior of small sporadic AML and propose an optimal follow-up strategy.

Methods

The study is a retrospective analysis of 168 individuals who had hyperechoic lesions, suggestive of AML detected during abdominal ultrasound as a part of their health checkup. The clinical information of the individuals, including tumor characteristics and renal function, was reviewed. Statistical analysis was performed to identify factors associated with tumor growth and renal function.

Results

Most AMLs were small (≤20 mm) and did not exhibit malignant characteristics. The tumors showed a slow growth rate, with a mean growth rate of 0.24 mm/year. Only a small proportion of cases (1.2%) required intervention due to significant enlargement. Factors such as tumor size and gender were not significantly associated with tumor growth rate or renal function. However, younger patients showed a higher tumor growth rate and a more pronounced decline in renal function.

Conclusion

Small sporadic AMLs have a slow growth rate and little risk of malignancy. Neither tumor size nor gender was predictive factors for tumor growth or renal function. Nevertheless, close monitoring of tumor growth and renal function is advised, particularly in younger patients. This study highlights the need for further research and guidelines to establish an optimal surveillance protocol for small AMLs.

Wunderlich Syndrome: A Seldom Presentation of a Relatively Ubiquitous Tumor

Wunderlich syndrome (WS) is characterized by spontaneous renal or perinephric hemorrhage in the absence of known trauma. WS is much rarer than haemorrhage caused by iatrogenic or traumatic conditions. The classic WS presentation of Lenk's triad of acute onset flank pain, flank mass, and hypovolemic shock is seen in less than a quarter of patients. The majority of patients present with only isolated flank pain and are frequently imaged in the emergency department with an unenhanced computed tomography (CT). The underlying aetiology varies, with the majority of cases attributed to neoplasms, vascular disease, cystic renal disease, and anticoagulation. We hereby present a case of an 80-year-old female who presented with severe discomfort in her left flank for three days in the absence of trauma. The patient was brought in a state of hypovolemic shock. After a thorough evaluation, a diagnosis of WS secondary to angiomyolipoma was made, for which selective angioembolization of the left renal artery was performed. However, due to further deterioration, a left nephrectomy had to be performed. The patient had an uneventful recovery and showed no deterioration on follow-up. The treatment modalities are vivid depending on the hemodynamic status of the patient, ranging from conservative management to operative intervention, and should be tailored to the vital state on admission.

Active Surveillance for Renal Angiomyolipoma Less Than 4 Centimeters: A Systematic Review of Cohort Studies

The aim of this review is to evaluate the current evidence regarding the best management in terms of active surveillance of angiomyolipoma (AML) cases less than 4 cm, particularly the optimal timing of active surveillance. In addition, we aimed to describe their initial size, clinical presentation, and growth rates. The present systematic review included prospective and retrospective studies that evaluated and followed up patients with AML through active surveillance. Studies were retrieved through an online bibliographic search of the Medline database via PubMed, SCOPUS, Web of Science, and Cochrane Library from their inception to January 2022. Seven studies were included in the present systematic review. Concerning the active surveillance protocol, only four studies describe the frequency of active surveillance and the utilized imaging modality. Some studies followed up lesions by ultrasound annually for two to five years, while other studies followed-up patients twice for the first year, then annually for a median follow-up period of 49 (9-89) months. The used modalities were ultrasound, CT, and magnetic resonance imaging (MRI). Notably, the incidence of spontaneous bleeding was consistent across the included studies (ranging from 2.3 - 3.1%), except for one study which showed an incidence rate of 15.3%. In terms of the need for active treatment, the rate of active treatment was slightly higher in some studies than the others. However, this variation could not be considered clinically relevant to favor one surveillance strategy over the other. We concluded that active surveillance is the first line of management in all small asymptomatic ALMs. ALMs less than 2 cm do not require active surveillance. The current published literature suggested that active surveillance for two years may provide the same benefits as a five-year surveillance strategy, with fewer radiation hazards and less socioeconomic burden.

Transarterial Embolization for Sporadic Renal Angiomyolipoma: Patient Selection and Technical Considerations for Optimal Therapeutic Outcomes

Although renal angiomyolipoma (AML) is a benign tumor, treatment may be necessary occasionally because it can cause potentially life-threatening retroperitoneal hemorrhage. Transarterial embolization (TAE) is a safe and effective treatment option to prevent the hemorrhagic rupture of AMLs and relieve the symptoms caused by enlarged lesions or active bleeding. However, there is no clear consensus regarding the indications for prophylactic TAE in patients with sporadic renal AMLs. In urgent TAE for bleeding AMLs, there is a likelihood of incomplete embolization when the focus is on stabilizing the clinical symptoms. This pictorial essay discusses the patient selection and technical considerations to achieve optimal therapeutic effects as well as the follow-up findings after TAE.

Is There a Higher Incidence of Sporadic Renal Angiomyolipoma in Childhood Cancer Survivors?

Background

Cancer treatment can cause various long-term side effects, including those that impact ultrasound findings. During follow-up of childhood cancer survivors (CCSs), we often detected sporadic renal angiomyolipomas without histological confirmation (SAMLs), which is why we initiated this study. We compared the occurrence of SAML in CCSs to the previously reported data from a non-cancer population and correlated SAML with cancer treatment-related factors.

Methods

The cohort included 1098 CCSs (median age at cancer diagnosis (dg) 4.3 years) who had ultrasound follow-up (2014-2019). Of the CCSs, 525 (48%) were female, 132 (12%) had subsequent neoplasms (SNs), and 110 (10%) had genetic syndromes. CCSs were treated for lymphomas 269 (24%) and solid tumors 829 (76%). None of the CCSs had tuberous sclerosis complex (TSC).

Results

SAML developed in 48 (4.4%) CCSs; of these, 20 (42%) had SNs. The coincidence of SAMLs and SNs was found in CCSs with a follow-up period exceeding 20 years. The median age at SAML dg was 27.9 years (interquartile range (IQR) 22.3-34.1), and the median time to SAML dg was 22.6 years (IQR 17.4-27.6). Twenty-one (44%) CCSs developed multiple or bilateral SAMLs lesions; of these, six (12%) were in the radiotherapy field. SAML occurrence correlated with radiotherapy of the retroperitoneum (1.65-fold higher with 95% CI 0.90-3.02). The correlations with other cancer treatment factors and with female sex were less clear.

Conclusion

This study revealed the occurrence of SAMLs in CCSs to be 10 times higher than that in non-cancer studies. The current characteristics of CCSs with SAMLs: younger age, and more bilateral or multiple lesions are more similar to TSC associated angiomyolipoma. Moreover, we observed a coincidence of SAMLs with SNs. Our results support the hypothesis that SAML development in CCSs is not simply a late effect of therapy, and indicates other factors are involved in SAML development.

Evidence-based protocol-led management of renal angiomyolipoma: A review of literature

Renal angiomyolipomas (R-AMLs) are rare benign tumors, which occur sporadically and in association with genetic conditions such as tuberous sclerosis complex (TSC) and lymphangioleiomyomatosis (LAM). The key clinical concern is life-threatening hemorrhage. There is uncertainty about the optimal management strategy for patients with R-AMLs. We aim to review the evidence and provide a protocolled approach for the management of R-AMLs. A literature search of R-AML was conducted using MEDLINE and EMBASE for articles published between January 1990 and March 2020. Patient with TSC and sporadic cases were included. Treatment strategies, including active surveillance, surgery, selective arterial embolization (SAE), ablation, and systemic therapies, were reviewed. Outcomes from contemporary case series of active surveillance, surgery, and SAE were collated. There were no randomized controlled trials on this topic. The retrospective case series reviewed showed that many R-AMLs can be managed safely with active surveillance. Tumor size is the most important predictor of bleeding, and other factors such as rate of growth, women of child-bearing age, aneurysm size, and symptoms should be considered when deciding on prophylactic treatment. There is limited evidence for the traditional 4-cm cutoff for treatment, which may lead to overtreatment. The primary intervention options are SAE and surgery; whereas SAE is a less invasive option, nephron sparing surgery offers a lower risk of recurrence. Both appear to have similar morbidity, and the current evidence does not recommend one over the other in most cases. Thermal ablation has promising results but has only been trialed in small case series. Patients with TSC can be offered mammalian target of rapamycin inhibitors of which everolimus appears to cause the greatest shrinkage of tumors with an acceptable side-effect profile. R-AMLs should be assessed for their risk of bleeding. Low-risk tumors should be treated with active surveillance. High-risk tumors should be treated with SAE or surgery. Systemic treatments are the first-line of treatment for patients with TSC to preserve renal parenchyma.

Partial nephrectomy can be a successful treatment option for renal epithelioid angiomyolipoma: a case report and literature review

Background

Renal epithelioid angiomyolipoma is a rare tumour which involves kidneys in most cases. It is known for its aggressive behaviour as a significant number of cases have been associated with metastatic epithelioid angiomyolipoma. Usually, radical treatment with systemic therapy is recommended. Only a small number of cases of epithelioid angiomyolipomas have been reported with the standard treatment being radical or partial nephrectomy. We present a  case report showing that partial nephrectomy can be a successful treatment option for renal epithelioid angiomyolipoma. This is the first case of this nature in Lithuania.

Case presentation

In this case, a 40-year-old male with epithelioid angiomyolipoma of the left kidney is presented. In 2012, a cystic left renal mass 40 × 41 mm in size was diagnosed incidentally while performing ultrasound and later confirmed by MRI. Due to the size of the tumour and the possibility of renal cell carcinoma, surgery was scheduled. Left partial nephrectomy was performed successfully. Final pathology report came back with the diagnosis of renal epithelioid angiomyolipoma. The patient had yearly follow-up for six years by CT scan, and neither recurrence nor progression were observed.

Conclusions

Early detection and diagnosis are crucial for treatment as the tumour tends to have malignancy potential. With early diagnosis, partial nephrectomy can be performed with yearly follow-up and no systemic treatment required.

A scoring system based on clinical features for the prediction of sporadic renal angiomyolipoma rupture and hemorrhage

The purpose of this study is to analyze the risk factors of sporadic renal hamartoma and establish a risk scoring system, and to intervene in patients with high-risk sporadic renal hamartoma who are prone to rupture and bleeding as soon as possible.Retrospective univariate and multivariate logistic analyzes were conducted for clinical data of 332 sporadic renal hamartoma patients to screen out independent risk factors of tumor rupture. Score of each independent risk factor was calculated. (Calculation formula: the risk coefficient of each factor = the beta regression coefficient of each factor/the minimum value of the beta regression coefficient of all factors, the value of the smallest beta regression coefficient corresponding to all the factors was assigned 1 point. The score of each factor was equal to the risk coefficient of each variable was taken as an integer value by rounding.) The total score was equal to the sum of all factors. Then the area under the receiver operating characteristics (AUC) curve was compared between high risk factors and scoring system. Finally, the scoring system was evaluated by the area under the curve (AUC) and the Hosmer-Lemeshow method in an independent cohort of 130 patients.Factors such as symptoms at presentation, tumor size, tumor blood supply, and tumor growth pattern were significant predictors of sporadic renal angiomyolipoma rupture in both the univariate and multivariate analyses; these predictors were included in the scoring system to predict sporadic renal angiomyolipoma rupture. There were no significant differences in AUCs between high risk factors and scoring system (z = 0.6434, P = .583, AUC = 0.913, and 0.903 for high risk factors and scoring system, respectively). The sporadic renal angiomyolipoma patients who scored >6 points were prone to rupture. AUROC of the scoring system in the validation set was 0.854(95%CI:0.779, 0.928). Using the Hosmer-Lemeshow method, the value of X was 2.916, P = .893, suggesting the scoring system fitted well.A scoring system based on clinical features is simple and effective in predicting sporadic angiolipoma rupture and hemorrhage. When the score is higher than 6 points, the probability of hamartoma rupture and hemorrhage is significantly increased and early intervention is needed.

Comparisons of the safety and effectiveness of robot-assisted versus laparoscopic partial nephrectomy for large angiomyolipomas: a propensity score-matched analysis

OBJECTIVE

To compare the safety and effectiveness of robot-assisted partial nephrectomy (RAPN) versus laparoscopic partial nephrectomy (LPN) for large angiomyolipomas (AMLs).

MATERIALS AND METHODS

We retrospectively evaluated 150 patients who were treated with either RAPN or LPN for large angiomyolipomas from 2014 to 2018. Propensity score matching was performed on age, gender, BMI, Charlson Comorbidity Index, tumour side and size, preoperative eGFR and RENAL score.

RESULTS

In total, 63 and 87 patients underwent RAPNs and LPNs, respectively. There were more large and complex AMLs in the RAPN cohort, with the median tumour maximal diameters and RENAL scores differing between the two groups (8 versus 7 cm and 9 versus 8, P = 0.01). After matching, the median warm ischemic time was significantly shorter in the RAPNs versus the LPNs (17 versus 22 min, P = 0.001). The rate of intraoperative complications in the RAPNs appeared lower than the LPNs (3.2% versus 8.1%). The median postoperative length of stay was significantly shorter in the RAPN cohort than the LPNs (P = 0.001). Twelve months after surgery, RAPNs received a 94.6% renal function prevention; while this was 90.8% in LPNs (P = 0.001). Subgroup analysis indicated that prior selective arterial embolization (SAE) was related to better renal function preservation in the RAPN cohort (P = 0.01). No recurrence occurred in either of the two cohorts.

CONCLUSIONS

RAPN is a safe and effective alternative to LPNs for large AMLs with a shorter warm ischemic time and higher renal preservation rate. Recurrence was equivalent in both RAPNs and LPNs.

Huge renal epithelioid angiomyolipoma - A case report of a giant, benign renal mass

INTRODUCTION

Renal angiomyolipoma (also called renal hamartoma) is a benign Tumor, composed of adipose tissue, smooth muscle tissue, and blood vessels. Tumors more than 10 cm (referred to as "giant" AMLs) are infrequent and a very small number of reported cases were measured more than 20 cm. Epithelioid angiomyolipoma (EAML), is a rare variant of angiomyolipoma with malignant potential. There are less than 10 cases of huge EAML reported in English literature, that were all associated with recurrence and complications.

CASE PRESENTATION

Here we report a rare case of renal EAML in a 48-year-old male patient that was not associated with tuberous sclerosis. He was admitted to our hospital with a complaint of severe abdominal pain. Computer Tomography Scan (CT-scan), revealed two masses attached to the left kidney with a size of 32 × 22 × 8 cm and 20 × 10 × 3 cm. The patient underwent a radical left nephrectomy. Postoperative histopathological examination confirmed the diagnosis of an EAML. The two-year follow-up CT-scan showed no recurrence.

CONCLUSION

Malignant EAML, although rare, does exist. Thus, besides evaluations required for ruling out the diagnosis of renal sarcomas, surgeons must follow patients after total nephrectomy for possible recurrence. Benign cases can be completely cured by surgery and do not show recurrence at the end of the follow-up period.