Hepatic angiomyolipoma: mutation analysis and immunohistochemical pitfalls in diagnosis

Risk prediction criteria for the primary hepatic perivascular epithelioid cell tumour family, including angiomyolipoma: analysis of 132 cases with a literature review

AIMS

The hepatic perivascular epithelioid cell tumour (PEComa), including angiomyolipoma, exhibits diverse morphology and clinical behaviour; however, its prognostic features remain undefined. This study aimed to investigate its histological features and prognostic factors.

METHODS AND RESULTS

In total, 132 patients were included. Clinical data and histopathological slides were assessed along with the p53 and Ki-67 immunohistochemistry. Targeted next-generation sequencing was performed in three cases. Based on the histologic subtypes, 7 (10%), 36 (51%), 13 (18%), and 15 (21%) patients were classified as inflammatory angiomyolipoma, conventional angiomyolipoma, epithelioid angiomyolipoma, and PEComa not otherwise specified (NOS), respectively, among 71 patients who underwent surgical resection. We proposed the risk prediction criteria after defining primary tumour size ≥7 cm, infiltrative border, mitotic rate >1/10 mm2, necrosis, vascular invasion, and PEComa NOS as worrisome features, as follows: high-risk: ≥3 worrisome features; intermediate-risk: 1-2 features; low-risk: none of the features. Applying these criteria, 4 (6%), 31 (44%), and 36 (51%) patients were classified into high-, intermediate-, and low-risk groups, respectively. One patient each in the high-risk (25%) and intermediate-risk (3%) groups developed peritoneal metastases and intrahepatic recurrence, respectively, whereas none in the low-risk group showed disease progression. A literature review of clinically malignant hepatic PEComa family tumours was conducted, and upon application of our criteria, 62% (16/26) of the patients were classified as high-risk and 35% (9/26) as intermediate- or high-risk.

CONCLUSION

Our risk prediction criteria can effectively predict the clinical outcomes in primary hepatic PEComa.

Mesenchymal Tumors of the Liver: An Update Review

Hepatic mesenchymal tumors (HMTs) are non-epithelial benign and malignant tumors with or without specific mesenchymal cell differentiation. They are relatively uncommon. Except for mesenchymal hamartoma, calcified nested stromal-epithelial tumor, and embryonal sarcoma, most mesenchymal lesions are not specific to the liver. Pathologists face challenges in diagnosing HMTs due to their diverse morphologies and phenotypic variations. Accurate diagnosis is critical for directing appropriate patient care and predicting outcomes. This review focuses on mesenchymal tumors with a relative predilection for the liver, including vascular and non-vascular mesenchymal neoplasms. It provides a thorough and up-to-date overview, concentrating on clinical and pathological features, differential diagnosis, and diagnostic approaches.

Unveiling the mystery of hepatic epithelioid angiomyolipoma: A unique case report with literature review

Hepatic epithelioid angiomyolipoma is a rare mesenchymal liver tumor within the perivascular epithelioid cell tumor family, known for its uncertain malignancy and potential for aggressive behavior. Clinical presentation, laboratory findings, and imaging results lack specificity, making pathological examination critical for definitive diagnosis. This case report presents a 61-year-old male patient with a single tumor in the right liver lobe, measuring approximately 101 mm × 99 mm. Initial imaging misdiagnosed the mass as hepatocellular carcinoma. Following multidisciplinary treatment discussions and subsequent tumor resection, histopathology and immunohistochemistry confirmed hepatic epithelioid angiomyolipoma. Accurate diagnosis of hepatic epithelioid angiomyolipoma is challenging, relying on histopathological examination and immunohistochemistry as diagnostic standards. Continuous monitoring of patients with hepatic epithelioid angiomyolipoma over an extended period is deemed essential. This report highlights the positive impact of multidisciplinary treatment in diagnosing and managing hepatic epithelioid angiomyolipoma.

Pathology and diagnostic approaches to well-differentiated hepatocellular lesions: a narrative review

Well-differentiated hepatocellular lesions (WDHLs) are liver tumors or nonneoplastic lesions in which the cells closely resemble normal hepatocytes. These lesions often include focal nodular hyperplasia, hepatocellular adenoma, macroregenerative nodule, dysplastic nodule, and well-differentiated hepatocellular carcinoma. The diagnosis of these lesions remains challenging because of their morphological similarities, particularly when examined using needle biopsy. The accurate diagnosis of WDHLs is crucial for patient management and prognosis. This review addresses the histopathological characteristics and diagnostic approaches of WDHLs.

Fat-Poor Hepatic Angiomyolipoma in Noncirrhotic Livers: Imaging Features, Pathology, and Differential Diagnosis

OBJECTIVE

To investigate imaging features of fat-poor hepatic angiomyolipomas in noncirrhotic livers in order to enhance the diagnostic accuracy for this condition.

METHODS

The clinical and imaging data of 19 patients with fat-poor hepatic angiomyolipoma (fpHAML) was retrospectively analyzed.

RESULTS

Of the 19 patients without hepatitis, cirrhosis, or sarcoidosis, 16 had no clinical symptoms. There were 20 lesions in 19 patients. Macroscopic fat, calcification, hemorrhage, necrosis, and pseudocapsule were not observed in the 20 lesions. All lesions showed marked enhancement on the arterial phase, and the degree of enhancement was significantly higher than that in the adjacent hepatic parenchyma. In 8 cases, the enhancement of the portal phase was higher than that in the arterial phase. Multiple intratumor vessels were observed in the tumor, and lesions with diameters larger than 3.0 cm were more frequently observed. The degree of enhancement of 18 lesions on portal phase or delayed phase was slightly higher than or equal to that in the surrounding hepatic parenchyma. The lesions were hyperintense on diffusion-weighted imaging and showed homogeneous hypointensity on the hepatobiliary phase. Only 6 cases showed the presence of an early draining vein.

CONCLUSIONS

These imaging features have some implications for the diagnosis of fpHAML. Therefore, an increased awareness of fpHAML is needed among radiologists.

TSC2 inactivation, low mutation burden and high macrophage infiltration characterise hepatic angiomyolipomas

AIMS

Although TSC1 or TSC2 inactivating mutations that lead to mTORC1 hyperactivation have been reported in hepatic angiomyolipomas (hAML), the role of other somatic genetic events that may contribute to hAML development is unknown. There are also limited data regarding the tumour microenvironment (TME) of hAML. The aim of the present study was to identify other somatic events in genomic level and changes in TME that contribute to tumorigenesis in hAML.

METHODS AND RESULTS

In this study, we performed exome sequencing in nine sporadic hAML tumours and deep-coverage targeted sequencing for TSC2 in three additional hAML. Immunohistochemistry and multiplex immunofluorescence were carried out for 15 proteins to characterise the tumour microenvironment and assess immune cell infiltration. Inactivating somatic variants in TSC2 were identified in 10 of 12 (83%) cases, with a median allele frequency of 13.6%. Five to 18 somatic variants (median number: nine, median allele frequency 21%) not in TSC1 or TSC2 were also identified, mostly of uncertain clinical significance. Copy number changes were rare, but detection was impaired by low tumour purity. Immunohistochemistry demonstrated numerous CD68+ macrophages of distinct appearance from Küpffer cells. Multiplex immunofluorescence revealed low numbers of exhausted PD-1+/PD-L1+, FOXP3+ and CD8+ T cells.

CONCLUSION

hAML tumours have consistent inactivating mutations in TSC2 and have a low somatic mutation rate, similar to other TSC-associated tumours. Careful histological review, standard IHC and multiplex immunofluorescence demonstrated marked infiltration by non-neoplastic inflammatory cells, mostly macrophages.

Epithelioid hepatic angiomyolipoma in pregnancy: A case report

INTRODUCTION AND IMPORTANCE

Epithelioid hepatic angiomyolipoma (HAML) is a rare benign tumor predominantly found in women. Its occurrence during pregnancy is extremely rare. Accurate diagnosis of HAML is challenging due to its radiological resemblance to other hepatic neoplasms. We present a case of epithelioid HAML in a pregnant patient, highlighting the diagnostic and management challenges encountered.

CASE PRESENTATION

A 24-year-old pregnant female, in her fifth month of pregnancy, presented with right hypochondrium pain and nausea. Radiological imaging suggested the possibility of a hepatic adenoma. The patient opted to continue the pregnancy with regular monitoring of the mass as well as fetal health. After delivering a healthy baby, the patient underwent successful mass excision and cholecystectomy. Histopathology of the liver mass confirmed the diagnosis of epithelioid HAML.

CLINICAL DISCUSSION

Epithelioid HAML is a rare tumor often misdiagnosed. It is more aggressive and frequently associated with tuberous sclerosis complex (TSC) compared to other subtypes. The diagnosis of HAML can be challenging due to its resemblance to Hepatocellular Carcinoma and other hepatic neoplasms on radiological imaging. Immunohistochemistry plays a crucial role in confirming the diagnosis. Surgical excision is the recommended treatment, with complete removal to minimize the risk of recurrence.

CONCLUSION

This case report highlights the rarity of epithelioid HAML during pregnancy and emphasizes the importance of a multidisciplinary approach in managing hepatic neoplasms. Close monitoring is crucial, considering the potential risks to the mother and fetus. Accurate diagnosis through histopathological evaluation, immunohistochemistry and a multidisciplinary approach are essential for appropriate management.

Uncommon Benign Neoplasms and Pseudotumors of the Liver

CONTEXT.—

The most common benign hepatic mass-forming lesions often display fairly specific imaging characteristics, whereas less familiar, rarer benign neoplasms and pseudotumors may pose a diagnostic challenge in clinical, radiology, and pathology practice because of either their rarity or their unusual features.

OBJECTIVE.—

To review a selection of pseudotumors and unusual benign hepatic neoplasms encountered in consultation practices with a focus on nonepithelial tumors.

DATA SOURCES.—

Sources include English-language literature and personal experiences.

CONCLUSIONS.—

Several benign conditions (namely, segmental atrophy, infections, immunoglobulin G4 [IgG4]-related sclerosing disease, angiomyolipoma, mesenchymal hamartoma, and various vascular lesions) can lead to formation of hepatic masses. Because of their rarity and underrecognition, such lesions are often diagnostically challenging. Awareness of hepatic pseudotumors and various rare hepatic neoplasms and their potential mimics can forestall misdiagnosis and inappropriate management.

Giant hepatic angiomyolipoma presenting with severe anemia: A surgical case report and review of literature

Background

Angiomyolipoma (AML) is a solid benign neoplasm with mesenchymal features. The clinical signs and symptoms of hepatic angiomyolipoma are nonspecific, and treatment strategy is variable.

Presentation

A 35-years-old male patient has admitted to the hospital with symptoms of severe anemia. Abdominal multi-slice computed tomography (MSCT) and Gadoxetic acid (GA)-enhanced magnetic resonance imaging (MRI) revealed a heterogeneous 23 × 17 cm-in-sized tumor with heterogeneous enhancement and increased angiogenesis. Percutaneous hepatic biopsy was proceeded and in immunohistochemistry, tumor cells responded positively to the HMB-45, SMA, and Glutamine stains, the CD-34 stain was positive for blood vessels as well as Ki-67 sporadically positive, but the Heppar1, S-100, CK stains reacted negative. The final pathologic result was consistent with the primary hepatic angiomyolipoma. The final surgical management was extended right hepatectomy with ligation of the right hepatic artery (RHA) and vein (RHV), as well as the middle hepatic vein (MHV), one month after portal embolization as well as to enlarge the remnant liver volume.

Discussion

A hepatic angiomyolipoma (HAML) primary origin is relatively rare, the clinical manifestations are variable and non-specific. Histological examination and immunohistochemistry staining are considered as the gold standard for HAML diagnosis. HAML are commonly expressed benign behaviors, but HAML cases with malignant behaviors were reported in a cumulative incidence. Radical surgery must be still the most effective and major treatment approach.

Conclusion

The present case being the first case with initial syndrome of severe anemia accounted in the English literature. Giant angiomyolipoma is composed of blood vessels and could lead to extensive internal tumoral hemorrhage. We here present a report of this case with had primary hepatic angiomyolipoma with clinical picture of severe anemia.

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A hepatic angiomyolipoma (HAML) is occasionally rare, the clinical manifestations are variable and non-specific.

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Histological examination and immunohistochemistry staining are considered as the gold standard.

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Radical surgery is the most effective and major treatment approach for symptomatic or big-sized HAML.

Baseline and contrast-enhanced ultrasound features of hepatic epithelioid angiomyolipoma

BACKGROUND

Recurrence or metastasis after surgery had been reported in hepatic epithelioid angiomylipoma (epi-AML). Most hepatic epi-AMLs were misdiagnosed with hepatocellular carcinoma or other hepatic tumors before surgery.

OBJECTIVE

To describe the baseline and contrast-enhanced ultrasound (CEUS) features of hepatic epi-AMLs and to explore the potential ultrasonic features for prognosis.

METHODS

The retrospective study enrolled 67 patients (56 females, 11 males) with 67 pathologically confirmed hepatic epi-AML lesions. All the lesions were examined by baseline ultrasound and 42 lesions were examined using CEUS with SonoVue (Bracco, Milan, Italy) before surgery.

RESULTS

Baseline ultrasound features of hepatic epi-AMLs included heterogeneous echo (86.6%), well-defined border (68.7%), hypoecho (64.2%), regular morphology (62.7%), peripheral-tumor arc-shaped or ring-like vessels (53.7%), and low value of resistive index (0.51±0.08). CEUS features of hepatic epi-AMLs included arterial phase hyper-enhancement with smooth and well-defined margin (100%), peripheral-tumor ring-like vessels (57.1%), and intra-tumor vessels (52.4%). Some CEUS features, including arterial phase heterogeneously tortuous filling, intra-tumor vessels and peripheral-tumor ring-like vessels were more commonly found in hepatic epi-AMLs of uncertain malignant potential/malignant than in benign hepatic epi-AMLs (p <  0.05).

CONCLUSIONS

Baseline ultrasound and CEUS features may be useful in diagnosis of hepatic epi-AML, and some CEUS features may be indicative of its malignant potential.

Clinical characteristics and outcomes of patients with hepatic angiomyolipoma: A literature review

First reported in 1976, hepatic angiomyolipoma (HAML) is a rare mesenchymal liver tumor occurring mostly in middle-aged women. Diagnosis of the liver mass is often incidental on abdominal imaging due to the frequent absence of specific symptoms. Nearly 10% of HAMLs are associated with tuberous sclerosis complex. HAML contains variable proportions of blood vessels, smooth muscle cells and adipose tissue, which renders radiological diagnosis hazardous. Cells express positivity for HMB-45 and actin, thus these tumors are integrated into the group of perivascular epithelioid cell tumors. Typically, a HAML appears on magnetic resonance imaging (or computed tomography scan) as a hypervascular solid tumor with fatty areas and with washout, and can easily be misdiagnosed as other liver tumors, particularly hepatocellular carcinoma. The therapeutic strategy is not clearly defined, but surgical resection is indicated for symptomatic patients, for tumors showing an aggressive pattern (i.e., changes in size on imaging or high proliferation activity and atypical epithelioid pattern on liver biopsy), for large (> 5 cm) biopsy-proven HAML, and if doubts remain on imaging or histology. Conservative management may be justified in other conditions, since most cases follow a benign clinical course. In summary, the correct diagnosis of HAML is challenging on imaging and relies mainly on pathological findings.

An update on subtypes of hepatocellular carcinoma: From morphology to molecular

The morphologic spectrum of hepatocellular carcinoma (HCC) is quite broad. While in about one-third of cases, the neoplasms can be categorized into meaningful subtypes based on morphology, a vast majority of these neoplasms are morphologically heterogeneous. With extensive tumor profiling, data has begun to emerge which can correlate specific morphologic features with underlying molecular signatures. A true morphologic subtype not only has reproducible H & E features, further supported by specific immunohistochemical or molecular signatures, but also has specific clinical implications and prognostic associations. Eight such morphologic subtypes are recognized by the 2019 WHO classification of tumors with a few more additional subtypes described in the literature. The goal of this review is to familiarize the reader with the morphologic subtypes and elaborate on the clinical and molecular associations of these neoplasms.

Hepatic Angiomyolipoma: Clinical Features and Imaging Findings of Quantitative Contrast-Enhanced Ultrasound Perfusion Analysis and Magnetic Resonance Imaging

OBJECTIVES

To investigate whether quantitative contrast-enhanced ultrasound (CEUS) analysis and magnetic resonance imaging (MRI) can differentiate hepatic angiomyolipoma (AML) from hepatocellular carcinoma (HCC) and hepatic epithelial angiomyolipoma (EAML) from nonepithelial AML.

METHODS

Retrospective analysis of 26 CEUS lesions pathologically confirmed as AML and 60 patients with confirmed HCC. Clinical and ultrasound (US) features of AML versus HCC and EAML versus nonepithelial AML were analyzed. Quantitative parameters, including arrival time, ascending slope, time to peak, peak intensity (PI), fall time (FT), and mean transit time (MTT), were analyzed. Diagnostic performance of MRI and CEUS was compared.

RESULTS

Angiomyolipoma was significantly different from HCC in US findings of solitary tumor (P < .001), well-defined border (P = .025), and hyperechogenicity (P < .001). Tumor types were significantly different in US findings of centripetal filling pattern (P < .001), less hypoenhancement in the CEUS delayed phase (P = .04), high PI (P = .007) and ascending slope (P = .006), and short FT (P = .001) and MTT (P < .05). The sensitivity and specificity of quantitative parameters were 61.5% to 96.2% and 55.0% to 71.7% (area under the curve, 0.642-0.773). An early draining vein and tumor vessels, intratumor fat, absence of pseudocapsules, mild signal intensity on diffusion-weighted imaging, and hypointensity in the MRI delayed phase were helpful for differentiation of AML from HCC (P < .05). The positive predictive values of CEUS and MRI were 46.3% to 100% and 42.9% to 75%, with no significant difference (P > .05). Epithelial AML was more likely to be hypoechoic with a centripetal filling pattern than nonepithelial AML (P < .05). The MTT and FT of EAML were shorter than those of nonepithelial AML (P < .05). The PI of EAML was significantly stronger than that of nonepithelial AML (P < .01). The sensitivity and specificity of quantitative parameters were 68.7% to 100.0% and 60.0% to 100.0% (area under the curve, 0.825-0.941). Less intratumor fat was helpful for differentiation of EAML from nonepithelial AML (P < .05). The positive predictive values of CEUS and MRI were 77.8% to 100% and 85.7%, with a significant difference (P < .05).

CONCLUSIONS

Quantitative CEUS findings could be valuable in differentiating EAML from HCC.

Epithelioid angiomyolipoma mimicking metastatic melanoma in a liver tumor

It is well known to pathologists that melanoma is "the great mimicker," looking like almost any other tumor, and able to metastasize anywhere in the body. We report a case of a 48-year-old female with a history of metastatic melanoma 4 years before, who presented with a hepatic mass. Microscopic examination of the liver mass revealed sheets of pleomorphic, epithelioid cells, which expressed a pan-melanocytic cocktail (MART1, HMB45, and tyrosinase). These findings were initially interpreted as metastatic melanoma and the case was transferred for dermatopathology consultation. We compared the morphology of this tumor to the primary melanoma and noticed that the primary melanoma showed nevoid cytology, morphologically distinct from the liver lesion. Consequently, we performed additional immunohistochemical studies, which determined that the liver mass was negative for S100 and SOX10, and established a final diagnosis of epithelioid angiomyolipoma. The key for reaching the correct diagnosis was the morphologic comparison with the original lesion and the evaluation of a wider immunohistochemical profile. For appropriate management in patients with new lesions, even in the context of a patient with known metastatic disease, it is essential to consider other neoplasms in the differential diagnosis.

Hepatic angiomyolipoma: an international multicenter analysis on diagnosis, management and outcome

BACKGROUND

Hepatic angiomyolipoma (HAML) may easily be misdiagnosed as a malignancy. The study aim was to assess diagnostic dilemmas, clinical management and outcome of this rare tumor.

METHODS

This retrospective international multicenter study included all patients with pathologically proven HAML diagnosed between 1997 and 2017. Data on patient characteristics, diagnostic work-up, management and follow-up were analyzed.

RESULTS

Thirty-eight patients were included, 32 female. Median age was 56yrs (i.q.r. 43-64) and median HAML-diameter was 57.5 mm (i.q.r. 38.5-95.3). Thirty patients had undergone CT and 27/38 MRI of the liver, diagnostic biopsy was performed in 19/38. Initial diagnosis was incorrect in 15/38 patients, of which 13 were thought to have malignancy. In 84% biopsy resulted in a correct preoperative diagnosis. Twenty-nine patients were managed with surgical resection, 4/38 with surveillance and 3/38 with liver transplantation. Recurrence after resection occurred in two cases. No HAML related deaths or progression to malignancy were documented.

CONCLUSION

HAML diagnosis proved problematic even in hepatobiliary expertise centers. Biopsy is indicated and may provide valuable additional information when HAML diagnosis is considered on cross-sectional imaging, especially when surgical resection imposes a risk of complications. Conservative management with regular imaging follow-up might be justified when biopsy confirms (classic type) HAML.

Hepatic monotypic epithelioid angiomyolipoma with concomitant hepatocellular carcinoma

Hepatic monotypic epithelioid angiomyolipoma (AML) is a rare lesion in which the predominant population of an epithelioid component can mimic hepatocellular carcinoma (HCC). The hepatic epithelioid AML with concomitant HCC is extremely uncommon. In this study, we present the clinical and pathologic features of a case of hepatic monotypic epithelioid AML with concomitant HCC in a 63-year-old man. Imaging examinations revealed two masses located in the liver, measuring 83×63 mm and 37×27 mm separately, which exhibited an early contrast enhancement and a rapid washout on enhanced computed tomography (CT), so that HCC with intrahepatic metastases was suspected. The small tumor was removed for intraoperative frozen section examination. Grossly, the tumor was solitary, well-circumscribed, and non-encapsulated. Microscopically, it was composed purely of a trabecular arrangement of epithelioid cells with a sinusoidal pattern. Immunohistochemically, it was positive for HMB45, Melan-A, and alpha smooth muscle actin (α-SMA). Interestingly, the large tumor has the histologic features similar to those of the small one. However, it was positive for epithelioid markers and negative for the melanocytic markers. It reminds us that there is a possibility of coexistence of HAML and HCC in the liver. We believe that this might be the first case report of a hepatic monotypic epithelioid AML with concomitant HCC. The patient gave up treatment and died in 6 months after the operation in the follow-up.