Clinical and pathological features of renal epithelioid angiomyolipoma (PEComa): A single institution series

Renal Epithelioid Angiomyolipoma: Prognostic Implications of Targeted Immunohistochemical and Molecular Markers in Conjunction with Clinicopathologic Features

Epithelioid angiomyolipoma (eAML) is an uncommon subtype of angiomyolipoma, a subset of which can demonstrate malignant behavior. While some studies have proposed histopathologic features predictive of aggressive behavior in eAML, there is limited data on the use of immunohistochemistry (IHC) and/or next-generation sequencing (NGS) to identify biomarkers for poor clinical outcome. Moreover, there is limited data on the proposed genetic dichotomy (tuberous sclerosis complex [TSC] alteration versus TFE3 rearrangement) of eAML. Clinicopathologic features (including purported histologic features associated with adverse outcome) of 30 eAML were recorded with IHC performed on 1 whole-slide section per tumor for the following markers (interpretations): p16 (positive or negative), p53 (wild type or mutant), TRIM63 ISH (>10% as positive or ≤10% as negative), ATRX (retained or lost), and RB1 (retained or lost). NGS was performed on 23 tumors. The 30 eAML tumors were from 30 patients (23 female, 7 male) of an age range 22 to 77 years (mean=51.9 y). Clinical follow-up was available from 27 patients (mean=36 mo). The features significantly associated with metastatic disease included ≥70% atypical epithelial cells (P=0.04), ≥2 mitotic figures per 10 high-power fields (P=0.0013), atypical mitotic figures (P=0.0003), and necrosis (P=0.0213). Other features such as local invasion, vascular invasion, tumor size, and immunohistochemical profile (p16, TRIM63, p53, ATRX, and RB1) showed no significant association with the development of metastasis. Interestingly, among the 7 tumors with clinical follow-up showing TFE3 rearrangement, 5 developed metastases (OR=4.50), while 6 of 14 TSC/MTOR mutated tumors with clinical follow-up had metastatic disease (OR=0.222). Notably, TRIM63 ISH showed high sensitivity (100%) for eAML with TFE3 rearrangement but with poor specificity (38%). The genetic dichotomy of eAML comes in the form of TSC/MTOR alterations or TFE3 rearrangement elucidated by NGS, both of which may be associated with poor outcome, and therefore show potential therapeutic implications. As eAML may show overlap with TFE3-rearranged/TFEB-altered renal cell carcinoma, shared TRIM63 ISH positivity for these tumor types represents an important potential diagnostic pitfall.

Renal PEComa in a young male: A case report and insights from the literature

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms, commonly found in the uterus and retroperitoneum. Renal PEComas are exceedingly rare, often posing diagnostic challenges due to their resemblance to renal cell carcinoma (RCC) on imaging. We present the case of an 18-year-old male who presented with non-specific symptoms of fever, chills, and shivering. Imaging revealed a renal mass, initially suspected to be RCC. However, following a right radical nephrectomy, histopathological examination confirmed the diagnosis of malignant PEComa. This case highlights the rarity of renal PEComa and underscores the importance of early diagnosis and appropriate surgical management to prevent complications.

Massive simultaneous hepatic and renal perivascular epithelioid cell tumor benefitted from surgery and everolimus treatment: A case report

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm that predominantly affects the kidney and uterus. The occurrence of this tumor in the liver, particularly with simultaneous involvement of the liver and kidney, is exceedingly uncommon. Pathological diagnosis is the gold standard. PEComas usually show positive immunohistochemical staining for melanocytic (HMB-45, Melan-A) and myoid (SMA, muscle-specific actin) markers.

CASE SUMMARY

We presented a noteworthy case of malignant PEComa affecting both the liver and kidney in a 53-year-old man with tuberous sclerosis complex (TSC). FAT2 and TP73 mutations in the kidney were identified and positive expression of diagnostic markers including HMB-45, Melan A, and TFE3 were detected. In addition, we demonstrated that hepatic artery perfusion chemotherapy was ineffective for hepatic PEComa, while surgery remained the most effective approach. Everolimus showed an excellent efficacy in the postoperative treatment of the tumor.

CONCLUSION

Surgical treatment is preferred for malignant PEComa affecting liver and kidney, especially with TSC; everolimus is effective postoperatively.

Renal epithelioid angiomyolipomas overexpress TFE3 and the TFE3-regulated gene TRIM63 in the absence of TFE3 rearrangement

Angiomyolipoma (AML) is a neoplasm within the perivascular epithelioid cell tumor family that occurs somewhat frequently in the kidney. Most are indolent and discovered incidentally, with rare tumors demonstrating malignant clinical behavior. A small subset of renal AMLs with epithelioid features are associated with aggressive behavior, and may demonstrate morphologic overlap with renal cell carcinomas (e.g., clear cell renal cell carcinoma (RCC), TFE3-rearranged RCC). Prior studies of spindle cell and epithelioid AMLs have identified rare examples with underlying TFE3 gene fusions. TFE3 protein expression (demonstrated by immunohistochemistry) with no evidence of concurrent TFE3 rearrangements has been reported previously in 4/24 AMLs (17%) (Argani et al. Am J Surg Pathol 34:1395-1406, 2010). Currently, the relationship between TFE3 protein expression, TFE3 fusions, and expression of TFE3-mediated genes remains incompletely understood in renal epithelioid AMLs. We sought to explore these relationships using TFE3 break-apart fluorescence in situ hybridization (FISH) and TRIM63 RNA in situ hybridization (ISH) on epithelioid AMLs with moderate to strong TFE3 expression by immunohistochemistry. RNA sequencing (fusion panel) was performed on two cases with negative FISH results to assess for FISH-cryptic gene fusions. The series comprised five epithelioid AMLs from four patients (three women, one man) aged 13 to 76 years. All were considered positive for TFE3 by immunohistochemistry (2 + /3 + expression). TRIM63 ISH was performed on four specimens from three patients, yielding positive results in 3/3 tumors (100%) that were successfully analyzed. TFE3 break-apart FISH was performed on all samples, demonstrating a TFE3 rearrangement in only 1/4 tumors (25%). RNA sequencing demonstrated the absence of productive TFE3 gene fusions in three tumors with negative break-apart TFE3 FISH results. This study demonstrates that renal epithelioid AMLs overexpress TFE3 and TFE3-mediated genes (TRIM63) even in the absence of TFE3 rearrangements. This finding could be explained by functional upregulation of TFE3 secondary to activation of the mammalian target of rapamycin complex 1 (mTORC1). Expression of TFE3 and TRIM63 in this tumor type represents a potential pitfall, given the morphologic and immunophenotypic overlap between epithelioid AML and TFE3-altered renal cell carcinoma.

Oncocytoma-Like Angiomyolipoma of the Kidney: A Closer Look into the Clinicopathologic, Immunohistochemical, and Molecular Characteristics of a Rare Entity with Review of the Literature

Introduction. Angiomyolipoma (AML) is a mesenchymal neoplasm that belongs to the perivascular epithelioid cell tumor family (PEComa). AMLs can be subtyped into several patterns dependent on cell type, morphology, and tissue composition. One of the patterns, oncocytoma-like AML is a rare entity with only three cases published in the literature. Case presentation. We present a case of a previously healthy 29-year-old woman who underwent a left partial nephrectomy secondary to a 4.6 cm heterogeneous renal neoplasm. Gross examination demonstrated a well-circumscribed renal mass. Modified Giemsa stain preparation showed oncocytic cells in syncytial pattern with ample granular cytoplasm and round nuclei with prominent nucleoli. Histology assessment showed an oncocytic neoplasm with interspersed adipose tissue. The tumor exhibited tubular architecture with the tubules lined by eosinophilic epithelioid cells with nuclear atypia and prominent nucleoli. Thick blood vessels with emanating epithelioid cells were present. High-grade histology features were not identified. The tumor cells were positive for HMB-45 and SMA and negative for PAX8, keratins, KIT, and vimentin. A diagnosis of oncocytoma-like AML was rendered. Next-generation sequencing (NGS) and RNA fusion were performed. NGS revealed no pathogenic variants and RNA fusion identified no rearrangements. Chromosomal copy number alterations were present in the long arm of chromosome 1 (1p) and chromosome 22. Conclusions. We describe and discuss the clinical, cytomorphologic, histologic, and molecular findings of oncocytoma-like AML, a rare renal neoplasm, and provide a review of the literature.

Pathology of hereditary renal cell carcinoma syndromes: Tuberous sclerosis complex (TSC)

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disease characterized by hamartomatous tumors involving multiple organs such as the brain, skin, heart, lung and kidney. TSC is caused by inactivating mutations in TSC1/TSC2, which encodes hamartin and tuberin, respectively, and forms a complex that regulates mechanistic target of rapamycin complex 1 (mTORC1), resulting in cell overgrowth and oncogenesis. Since a leading cause of morbidity and mortality in TSC relates to chronic kidney disease and the ability to preserve renal function, this review describes the important pathologic findings in TSC-associated renal neoplasms and their correlating sporadic counterparts. The most common renal tumor in TSC patients are AMLs, followed by a heterogeneous spectrum of renal epithelial tumors, which may provide clues to establishing a diagnosis of TSC.

Recurrence of Pigmented Epithelioid Angiomyolipoma of the Kidney With Xp11 Translocation: A Case Report

This case report pertains to a 70-year-old male patient with a medical history marked by atrial fibrillation, ankylosing spondylitis, and Crohn's disease. Eight years prior, the patient underwent a left radical nephrectomy due to the presence of a pigmented epithelioid angiomyolipoma (PEComa) in the kidney. Notably, pathological examination revealed an unusual subtype of PEComa characterized by Xp11 gene translocation, indicating a more aggressive clinical profile. Following a five-year observation period without recurrence, the patient was discharged. However, eight years after initial treatment, he presented with vague symptoms of left loin discomfort and fullness, which had persisted for several weeks. Subsequent evaluation via computed tomography (CT) scanning showed a small lesion at the site of the renal bed. Surgical resection confirmed the return of the identical tumour. Key clinical points elucidated by this case include the varied behaviour of PEComas, the essential need for prolonged surveillance, and a recognition that recurrences can transpire even after extended disease-free intervals. Prior studies suggest recurrence rates of up to 31.8% for this specific PEComa subtype, emphasising the requirement for prolonged follow-up protocols.

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.

Differentiating renal epithelioid angiomyolipoma from clear cell carcinoma: using a radiomics model combined with CT imaging characteristics

PURPOSE

This study aims to assess the computed tomography (CT) findings of renal epithelioid angiomyolipoma (EAML) and develop a radiomics-based model for differentiating EAMLs and clear cell renal cell carcinomas (RCCs).

METHOD

This two-center retrospective study included 28 histologically confirmed EAMLs and 56 size-matched clear cell RCCs with preoperative three-phase kidney CTs. We conducted subjective image analysis to determine the CT parameters that can distinguish EAMLs from clear cell RCCs. Training and test sets were divided by chronological order of CT scans, and radiomics model was built using ten selected features among radiomics and CT features. The diagnostic performance of the radiomics model was compared with that of the three radiologists using the area under the receiver-operating characteristic curve (AUC).

RESULTS

The mean size of the EAMLs was 6.2 ± 5.0 cm. On multivariate analysis, a snowman or ice cream cone tumor shape (OR 16.3; 95% CI 1.7-156.9, P = 0.02) and lower tumor-to-cortex (TOC) enhancement ratio in the corticomedullary phase (OR 33.4; 95% CI 5.7-197, P < 0.001) were significant independent factors for identifying EAMLs. The diagnostic performance of the radiomics model (AUC 0.89) was similar to those of genitourinary radiologists (AUC 0.78 and 0.81, P > 0.05) and superior to that of a third-year resident (AUC 0.63, P = 0.04).

CONCLUSIONS

A snowman or ice cream cone shape and lower TOC ratio were more closely associated with EAMLs than with clear cell RCCs. A CT radiomics model was useful for differentiating EAMLs from clear cell RCCs with better diagnostic performance than an inexperienced radiologist.