Clinicopathologic analysis of renal epithelioid angiomyolipoma: Consecutively excised 23 cases

Renal mass biopsy - a practical and clinicopathologically relevant approach to diagnosis

Advancements in imaging modalities have increased the frequency of renal mass discovery. Imaging has typically been considered sufficient to guide management for a large proportion of these tumours, but renal mass biopsies (RMBs) have an increasing role in determining malignancy and can be a valuable tool for preventing unnecessary surgery in patients with benign tumours. A structured approach should be used to help to navigate the expanding repertoire of renal tumours, many of which are molecularly defined. In terms of tumour subtyping, the pathologist's strategy should focus on stratifying patients into clinically different prognostic groups according to our current knowledge of tumour behaviour, including benign, low-grade or indolent, intermediate malignant or highly aggressive. Crucial pathological features and morphological mimicry of tumours can alter the tumour's prognostic group. Thus, pathologists and urologists can use RMB to select patients with tumours at a reduced risk of progression, which can be safely managed with active surveillance within a tailored imaging schedule, versus tumours for which ablation or surgical intervention is indicated. RMB is also crucial in the oncological setting to distinguish between different high-grade tumours and guide tailored management strategies.

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.

Epitheloid Angiomyolipomas of the Kidney: Rare Renal Tumors Associated With Poor Prognoses

OBJECTIVE

To demonstrate the clinical spectrum and challenges associated with clinical management of epitheloid angiomyolipomas (eAML).

METHODS

We retrospectively reviewed the surgical database of a high-volume tertiary kidney cancer center from 2015 to 2020 to identify cases with a final histological diagnosis of eAML. Descriptive analysis of all cases was conducted.

RESULTS

Five surgical cases of eAMLs were identified. Two of which have had no tumor recurrence since surgery, and three patients passed away due to disease progression.

CONCLUSION

eAML are rare renal tumors which the World Health Organisation (5th Edition, 2022) and International Classification of Diseases for Oncology classify as having unspecified, borderline, or uncertain behavior. Here, we report that can also demonstrate aggressive behavior with fatal consequences. Post-operative follow-up should be recommended for all, with shorter intervals for patients with poor prognostic factors.

Advancements in the diagnosis and treatment of renal epithelioid angiomyolipoma: A narrative review

Renal epithelioid angiomyolipoma (EAML) is a unique subtype of angiomyolipoma that contains a variety of cytoplasmic-rich, eosinophilic cytoplasm epithelioid cells in addition to mature adipocytes, hyaline thick-walled vessels, and smooth muscle-like spindle cells. In recent years, increasing evidence has shown that EAML is a potentially malignant tumor. Due to the lack of typical clinical manifestations and imaging features, it is difficult to diagnose before surgery, and the diagnosis mainly depends on postoperative histopathological examination. With the advancement of pathological diagnostic techniques, more EAML cases has been discovered, but clinicians still lack a comprehensive understanding of EAML. This review comprehensively describes some pathological and clinical features of EAML, with special attention to the pathogenesis and treatment of malignant EAML in order to assist with clinical diagnosis and treatment.

Renal epithelioid angiomyolipoma: computed tomography manifestation and radiologic-pathologic correlation depending on different epithelioid component percentages

BACKGROUND

Renal epithelioid angiomyolipoma (EAML) is a rare and potentially malignant mesenchymal lesion mainly composed of epithelioid cells. Although some case reports or small case series have been published, the computed tomography (CT) manifestations and radiologic-pathologic correlation depending on different epithelioid component percentages have not been studied before.

OBJECTIVE

To investigate the CT manifestation and radiologic-pathologic correlation between renal EAML and angiomyolipoma (AML) with epithelioid component.

METHODS

The clinicopathologic and imaging data of 53 patients with an original diagnosis of EAML or AML with epithelioid component were retrospectively collected from three hospitals. All tissue specimens were re-sectioned and re-observed under the microscope. Samples were divided into an EAML group (≥ 80% epithelioid component, n = 25) and AML with epithelioid component group (5% ≤ epithelioid component < 80%, n = 28). Two radiologists reviewed the images in consensus, describing and comparing the CT manifestation, including the long diameter of the tumor, morphology, presence of necrosis or cystic change, hemorrhage, fat, calcification, enlarged blood vessels, and dynamic enhancement pattern according to the Hounsfield unit value of each CT phase between the two groups. The radiologic-pathologic correlation depending on the different percentages of epithelioid component were studied.

RESULTS

The long diameter of the tumor, presence of necrosis or cystic change, fat, enhancement pattern, and tumor-to-cortex enhancement ratio of the cortical phase between the two groups were significantly different (z =  - 2.932, P = 0.003; χ² = 18.020, P < 0.001; χ² = 16.377, P < 0.001; P = 0.020; and T =  - 3.944, P < 0.001, respectively). In multivariate logistic regression analysis, the significant predictive factors of EAML included the presence of necrosis or cystic change [odds ratio (OR) 11.864, P = 0.001] and absence of fat (OR 0.095, P = 0.003). Correlation analysis found that the presence of necrosis or cystic change (r = 0.679, P < 0.001) and fat (r =  - 0.603, P < 0.001) were both moderately related to the epithelioid component percentage. The combined model based on the presence of necrosis or cystic change and absence of fat yielded the best diagnostic performance in discriminating EAML and AML with epithelioid component with the highest area under the curve (0.887).

CONCLUSION

EAML has characteristic CT signs; these characteristic CT signs are closely related to the epithelioid component percentage. The presence of necrosis or cystic change and the absence of fat were independent predictors of EAML.

A rare case of spontaneous rupture of epithelioid angiomyolipoma

A male patient, 40 years of age, arrived at our Institute with diffuse abdominal tenderness, right flank pain, hematuria and early stage of hemorrhagic shock with anemia and initial hypotension. The immediate clinical history revealed no significant previous trauma, only subsequently was reported inconstant pain in the right flank for 4–5 days with pallor and asthenia, signs and symptoms that the patient had not investigated. Abdominal CT scan with angiographic evaluation was performed showing right kidney mass and perirenal fluid collection by blood component. Immediate nephrectomy was performed and histopathological and further immunohistochemical study, revealed the epithelioid variant of angiomyolipoma.

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.

Renal angiomyolipoma with tuberous sclerosis complex: How it differs from sporadic angiomyolipoma in both management and care

Renal angiomyolipoma (AML) is the most common benign tumor of the kidney. It consists of blood vessels, smooth muscle and fat components in varying proportions. AML is divided into the sporadic type and tuberous sclerosis complex (TSC)-associated type. TSC-associated AML develops at a younger age and tends to exhibit a much faster growth rate over time than sporadic AML. AMLs are classified as classic AML, fat-poor AML and epithelioid AML. Epithelioid AML, though rare, shows aggressive behavior leading to distant metastasis and mortality. TSC-associated AML is more likely to have an epithelioid component than sporadic AML. Active surveillance is the suggested management for small AML. Clinical intervention is mainly indicated when there is a substantial risk of rupture. Minimally invasive therapies, including partial nephrectomy, transcatheter arterial embolization, and mammalian target of rapamycin (mTOR) inhibitor treatment are employed for patients who require treatment. An updated algorithm for the management of AML is herein described. According to this algorithm, treatment intervention is recommended for TSC-associated AML >3 cm, even in asymptomatic cases. In cases with asymptomatic sporadic AML >4 cm in size or with an intra-tumoral aneurysm of >5 mm, treatment, including transcatheter arterial embolization or partial nephrectomy, is advised. The major complication of AML is intra-tumoral or retroperitoneal hemorrhage due to rupture that may be serious and life threatening. Thus, correct diagnosis, proper observation, and appropriate treatment are very important in the management of renal AML.