Hepatic angiomyolipoma: a clinicopathologic study of 30 cases and delineation of unusual morphologic variants

A case report of IgG4-related hepatic inflammatory pseudotumor in a 3-year old boy

Background

Hepatic Inflammatory Pseudotumor (IPT) is an infrequent condition often masquerading as a malignant tumor, resulting in misdiagnosis and unnecessary surgical resection. The emerging concept of IgG4-related diseases (IgG4-RD) has gained widespread recognition, encompassing entities like IgG4-related hepatic IPT. Clinically and radiologically, corticosteroids and immunosuppressive therapies have proven effective in managing this condition.

Case Presentation

A 3-year-old Chinese boy presented to the clinic with an 11-month history of anemia, fever of unknown origin, and a tender hepatic mass. Blood examinations revealed chronic anemia (Hb: 6.4 g/L, MCV: 68.6 fl, MCH: 19.5 pg, reticulocytes: 1.7%) accompanied by an inflammatory reaction and an elevated serum IgG4 level (1542.2 mg/L). Abdominal contrast-enhanced computed tomography unveiled a 7.6 cm low-density mass in the right lateral lobe, while magnetic resonance imaging demonstrated slight hypointensity on T1-weighted images and slight hyperintensity on T2-weighted images, prompting suspicion of hepatic malignancy. A subsequent liver biopsy revealed a mass characterized by fibrous stroma and dense lymphoplasmacytic infiltration. Immunohistochemical analysis confirmed the presence of IgG4-positive plasma cells, leading to the diagnosis of IgG4-related hepatic IPT. Swift resolution occurred upon initiation of corticosteroid and mycophenolate mofetil therapies.

Conclusion

This study underscores the diagnostic approach to hepatic IPT, utilizing histopathology, immunostaining, imaging, serology, organ involvement, and therapeutic response. Early histological examination plays a pivotal role in clinical guidance, averting misdiagnosis as a liver tumor and unnecessary surgical interventions.

Hepatic angiomyolipoma masquerading as abdominal pain: A case report

INTRODUCTION AND IMPORTANCE

Hepatic angiomyolipoma (HAML) is a rare liver tumor composed of blood vessels, smooth muscle, and fat cells. HAML occurs across a wide age range, with symptoms including abdominal discomfort, bloating, and weight loss. Diagnosis is challenging due to varied imaging appearances, but histopathological examination supplemented by immunohistochemical analysis, particularly using HMB-45, is definitive.

CASE PRESENTATION

A 33-year-old man presented with a two-year history of right upper quadrant abdominal pain, occasionally relieved with analgesics but worsening over the past month and a half. Examinations revealed a soft, non-distended abdomen with a palpable liver. Laboratory tests, including viral markers and tumor markers were normal. Contrast-enhanced CT revealed a well-defined oval mass in liver segment III with heterogeneous enhancement leading to provisional diagnosis of HAML. The patient underwent a successful en bloc excision with no intraoperative or postoperative complications.

CLINICAL DISCUSSION

Surgical resection is recommended for symptomatic cases or inconclusive biopsies, with stringent follow-up necessary due to the potential for recurrence and association with other malignancies.

CONCLUSION

HAML may present with prolonged nonspecific abdominal symptoms. CT imaging aids in diagnosing cases with abundant fatty tissue. En bloc tumor excision proves safe and effective in treating symptomatic presentations.

Angiomyolipoma Originating From the Nasal Vestibule: A Case Report

Angiomyolipoma is a benign, mesenchymal, hamartomatous lesion often described in the kidney and may be associated with tuberous sclerosis. Nasal angiomyolipoma is an extremely rare tumor with fewer than 20 cases reported in the literature. We report a case of angiomyolipoma arising in the right nasal vestibule in a 68-year-old male with mild, recurrent right-sided epistaxis, and nasal obstruction. With the exception of arterial hypertension, the patient did not have any comorbidities. Gross examination showed a well-circumscribed, lobulated mass. On the microscopic level, it was composed of mature smooth muscle cells, thick-walled blood vessels of varying sizes, and islands of mature adipose tissue. Angiomyolipoma should be considered as a differential diagnosis for unilateral nasal masses, especially those situated in the nasal vestibule.

Transcatheter arterial embolization followed by laparoscopic anatomic hepatectomy for spontaneous rupture of a giant hepatic angiomyolipoma: a case report

Hepatic angiomyolipoma is a rare and possibly cancerous mesenchymal tumor that consists of three components: blood vessels, smooth muscle cells, and adipose tissue. In this paper, we reported a case of a 36-year-old man who had a giant hepatic angiomyolipoma with spontaneous rupture and hemorrhage. The patient was admitted to our hospital with sudden upper abdominal pain for 3 h. A giant tumor was found in the left and caudate lobes of the liver, as well as significant blood collection around the liver and in the pelvis. Hemoglobin, liver function test results, and serum tumor maker levels were all within normal ranges. To prevent bleeding, emergency angiography and embolization were performed. During angiography, it was discovered that the tumor was supplied by the left hepatic artery and had a very rich internal blood supply. A massive left hepatic mass of about 11 cm in diameter was found bulging from the surface of the liver and rupturing there during laparoscopic exploration a week later. The rupture was strongly adhered to the smaller curvature of the stomach. The patient underwent laparoscopic left hemihepatectomy and caudate lobectomy, and the tumor specimen was brown, with clear boundaries with the surrounding normal liver parenchyma, and there were a large number of necrotic lesions inside the tumor. Histopathological results confirmed the mass as hepatic angiomyolipoma with negative resection margins. Immunohistochemical staining indicated that the tumor had positive homatropine methylbromide-45. After 13 months of follow-up, no tumor recurrence or metastasis occurred in the patient.

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.

Mesenchymal Neoplasms of the Liver

Mesenchymal neoplasms of the liver can be diagnostically challenging, particularly on core needle biopsies. Here, I discuss recent updates in neoplasms that are specific to the liver (mesenchymal hamartoma, undifferentiated embryonal sarcoma, calcifying nested stromal-epithelial tumor), vascular tumors of the liver (anastomosing hemangioma, hepatic small vessel neoplasm, epithelioid hemangioendothelioma, angiosarcoma), and other tumor types that can occur primarily in the liver (PEComa/angiomyolipoma, inflammatory pseudotumor-like follicular dendritic cell sarcoma, EBV-associated smooth muscle tumor, inflammatory myofibroblastic tumor, malignant rhabdoid tumor). Lastly, I discuss metastatic sarcomas to the liver, as well as pitfalls presented by metastatic melanoma and sarcomatoid carcinoma.

Inflammatory Pseudotumor of the Liver

Hepatic inflammatory pseudotumor (IPT) describes a mass lesion composed of fibroblasts or myofibroblasts with a dense inflammatory infiltrate comprising lymphocyte, plasma cells, and histiocytes. These lesions are presumed to be an exuberant response to an infectious organism, although in most cases the causative agent is unknown. In specific circumstances, pathologists should consider ancillary techniques to exclude specific infections, such as mycobacteria, Candida, or syphilis. IgG4-related disease may cause a plasma-cell rich IPT. Finally, true neoplasms can mimic IPTs and must be excluded with appropriate ancillary studies, including inflammatory myofibroblastic tumor, follicular dendritic cell tumor, inflammatory angiomyolipoma, Hodgkin lymphoma, and inflammatory hepatocellular carcinoma.

Hepatic epithelioid angiomyolipoma: magnetic resonance imaging characteristics

PURPOSE

The aim of the study was to analyze MR imaging features of hepatic epithelioid angiomyolipoma (HEAML).

METHODS

This study included 113 patients with 122 pathologically confirmed HEAML who underwent enhanced MRI scanning before partial hepatectomy. MR images were retrospectively reviewed and correlated with pathological findings.

RESULTS

The mean age of 113 patients was 48.12 ± 11.77 years old, and the male to female ratio was 1:3.35 with 87 females (76.99%). 107 (94.69%) patients presented as single tumor, and 96 patients (84.96%) were asymptomatic. 122 HEAML lesions were diagnosed pathologically in 113 patients, with the average of 4.47 ± 3.26 cm. 109 lesions (89.34%) and 108 lesions (88.52%) showed regular and well-defined boundary. On T1WI, 121 lesions (99.18%) mainly presented hypointensity. On T2WI, 118 lesions (96.72%) and 109 lesions (89.34%) mainly showed hyperintensity and heterogeneous signals. Most of the lesions (97.46%) showed hyperintensity on DWI. 118 lesions (96.72%) manifested as severe hyperenhancement and 106 lesions (86.89%) showed heterogeneity during the arterial phase. As for the lesion enhancement pattern, 73 lesions (59.84%) presented as persistent enhancement, 37 lesions (30.33%) as wash out, 8 lesions (6.56%) as degressive enhancement, and 4 lesions (3.28%) as poor blood supply. Additionally, 96 lesions (78.69%) with intra-tumor vessels and 85 lesions (69.67%) with outer rim were confirmed during the delayed phase.

CONCLUSION

At enhanced MRI, hypointensity on T1WI, hyperintensity and heterogeneous signals on T2WI, hyperintensity on DWI, little or no fat component, heterogenous hyperenhancement, persistent enhancement, intra-tumor vessels, and outer rim would be helpful to diagnose HEAML.

Cutaneous Angiomyolipoma-A Distinct Entity That Should Be Separated From Classic Angiomyolipoma: Complete Review of Existing Cases and Defining Fundamental Features

Cutaneous angiomyolipoma is a rare mesenchymal tumor that is demographically, clinically, and immunohistochemically distinct from its renal and extrarenal counterparts. We present a case of cutaneous angiomyolipoma in the right retroauricular area of a 35-year-old male patient and provide a broad systematic review of the literature and the largest compilation of cutaneous angiomyolipomas reported to date. According to the findings presented in this review, we conclude that cutaneous angiomyolipoma should be completely separated from renal and extrarenal angiomyolipomas and therefore be considered a distinct entity in the classification of skin tumors.

Primary hepatic epithelioid angiomyolipoma: a small case series

BACKGROUND

Hepatic epithelioid angiomyolipomas (HEAMLs) are rare and usually arise in case reports, and thus, we aimed to study the clinicopathological features, treatment and prognosis of these lesions.

METHODS

We identified patients from institutional database with HEAMLs and retrospectively collected clinical data.

RESULTS

Of 12 patients, 10 were females, and the median age was 49 years. A liver mass was found on chance upon routine health screening in nine patients. Imaging features included clear border (9/12), internal heterogeneity (8/12), arterial enhancement (12/12), fat (5/12), intra-tumour vessel (3/12), draining hepatic vein (2/12) and pseudocapsule (1/12). The preoperative diagnoses contained HEAML (n = 5), hepatocellular carcinoma (n = 6), and hepatic cystadenocarcinoma (n = 1). All cases had received surgery and obtained a negative margin. All specimens showed positive findings for HMB-45 and Melan A. No tumour recurrence or mortality was described with a mean follow-up time of 23.5 months.

CONCLUSIONS

HEAML is a low potential malignancy tumour that frequently appears in middle-aged females. It has nonspecific symptoms and may present special imaging features including intra-tumour vessel, early draining hepatic vein and lack of a pseudo capsule. The lesion is confirmed by pathological and immunohistochemical findings. Surgery and subsequent long-term follow-up are the most appropriate management approaches.

Perivascular epithelioid cell tumour (PEComa): an unusual cause of painful defaecation

Perivascular epithelioid cell tumours (PEComa) are rare tumours of mesenchymal origin. We report a 39-year-old patient who presented with painful defecation secondary to an anorectal mass. The diagnosis of anorectal PEComa was confirmed following excision and histopathological examination. We review the literature and discuss the management of this uncommon entity.

Puzzling hepatic tumor: Epithelioid angiomyolipoma

Hepatic epithelioid angiomyolipomas are uncommon mesenchymal neoplasms. They are difficult to diagnose by imaging, especially when the fatty component is scant or absent. The gold standard for the diagnosis is histologic examination coupled with an immunohistochemical study. Positive HMB45 immunostaining of the myoid cells is a major diagnostic feature.

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.

More than Pus - Primary Hepatic Epithelioid Angiomyolipoma Masquerading as Liver Abscess

Hepatic angiomyolipomas (AML) are rare mesenchymal tumours of which the epithelioid type is a rare type with malignant potential. We report a case of primary hepatic epithelioid angiomyolipoma masquerading as liver abscess. A 46-year-old man presented with a 5-day history of fever with epigastric pain and nausea. On the night of admission, his temperature spiked to 39°C, his blood pressure was 135/79, his heart rate 98, his liver function test revealed albumin 37 g/L, bilirubin 25 μmol/L, ALP 298 U/L, ALT 247 U/L, and AST 344 U/L. The clinical suspicion was hepatobiliary sepsis and intravenous ceftriaxone was commenced. CT of the abdomen showed an ill-defined hypodense focus in segment 4A/8 (4.5 × 3.5 cm) with a minimal fluid component implying a developing abscess or phlegmon. The images were reviewed by a radiologist and showed minimal fluid for percutaneous drainage. MRI of the liver was performed to further characterize the lesion and revealed a solid mass with nodular areas of arterial enhancement and washout, suspicious of neoplasm. Ultrasound-guided liver biopsy of the lesion was performed. Histology showed a histiocyte-rich epithelioid neoplasm consistent with the epithelioid variant of AML. Immunohistochemical staining was positive for human melanoma black 45, melan-A and cluster of differentiation 68. He successfully underwent liver resection of segment 4A/8 after 6 weeks of antibiotics. To our knowledge, this is the first reported case in the literature of primary hepatic epithelioid angiomyolipoma masquerading as liver abscess.

Immunohistochemical Signature Add Prognostic Value in Patients With Early and Intermediate Hepatocellular Carcinoma Underwent Curative Liver Resection

Hepatocellular carcinoma (HCC) is the third most lethal cancer worldwide; however, accurate prognostic tools are still lacking. We aimed to identify immunohistochemistry (IHC)-based signature as a prognostic classifier to predict recurrence and survival in patients with HCC at Barcelona Clinic Liver Cancer (BCLC) early- and immediate-stage. In total, 567 patients who underwent curative liver resection at two independent centers were enrolled. The least absolute shrinkage and selection operator regression model was used to identify significant IHC features, and penalized Cox regression was used to further narrow down the features in the training cohort (n = 201). The candidate IHC features were validated in internal (n = 101) and external validation cohorts (n = 265). Three IHC features, hepatocyte paraffin antigen 1, CD34, and Ki-67, were identified as candidate predictors for recurrence-free survival (RFS), and were used to categorize patients into low- and high-risk recurrence groups in the training cohort (P < 0.001). The discriminative performance of the 3-IHC_based classifier was validated using internal and external cohorts (P < 0.001). Furthermore, we developed a 3-IHC_based nomogram integrating the BCLC stage, microvascular invasion, and 3-IHC_based classifier to predict 2- and 5-year RFS in the training cohort; this nomogram exhibited acceptable area under the curve values for the training, internal validation, and external validation cohorts (2-year: 0.817, 0.787, and 0.810; 5-year: 0.726, 0.662, and 0.715; respectively). The newly developed 3-IHC_based classifier can effectively predict recurrence and survival in patients with early- and intermediate-stage HCC after curative liver resection.

Hepatic angiomyolipoma with predominant epithelioid component: Diagnostic clues on aspiration and core needle biopsies

Hepatic angiomyolipoma (HAML) is a rare mesenchymal neoplasm that belongs to the perivascular epithelioid tumor family. Though it is characteristically, a triphasic tumor composed of smooth muscle, blood vessels, and adipocytes, the smooth muscle cells are often epithelioid and can represent the near-entirety of the tumor. A HAML composed predominantly of epithelioid smooth muscle cells occurring in the liver presents significant diagnostic challenges as many liver tumors are composed of large epithelioid cells. Furthermore, even if the tumor is not composed predominantly of epithelioid smooth muscle cells, this may be the only component present in a fine-needle aspiration (FNA) or core needle biopsy. A 38-year-old female with a 3 month history of abdominal pain, nausea, and diarrhea was found to have a 12 cm right hepatic lobe mass. FNA biopsy revealed a moderately cellular specimen composed of plump epithelioid cells with indistinct cell borders, low N:C ratio, round to oval nuclei, fine chromatin, occasional nucleoli, and abundant vacuolated to fibrillary cytoplasm. Rare intranuclear inclusions and occasional foamy macrophages were noted. Concurrent core biopsy revealed large polygonal cells with eccentric nuclei and clear, vacuolated to granular, eosinophilic cytoplasm that stained strongly for HMB45, confirming the diagnosis of HAML. Because HAML is a rare tumor, this diagnosis can be easily overlooked; cognizance of the typical cytologic, histologic, and immunophenotypic findings is crucial to establishing a diagnosis.

Hepatic angiomyolipoma: A case report and literature review

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HAML is a rare mesenchymal liver tumour which belongs to the family of perivascular epithelioid cell tumours.

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HAML is typically composed of blood vessels, smooth muscle, and adipose cells.

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HAML is characteristically positive for HMB-45.

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In patients with symptoms, uncertain diagnosis, or tumour growth, surgical resection should be performed.

Introduction

Hepatic angiomyolipoma (HAML) is a rare mesenchymal liver tumour which belongs to the family of perivascular epithelioid cell tumours (PEComas). It is typically composed of blood vessels, smooth muscle, and adipose cells, and shows strong immunoreactivity for HMB-45.

Presentation of the case

A 57-year-old woman was referred to our hospital with an unclear liver lesion. A fine needle biopsy revealed a suspicion of hepatic angiomyolipoma with extramedullary haematopoiesis. Preoperative imaging revealed a tumour 17 cm in diameter in the left liver lobe segments II and III. A lobectomy of the left lobe segments II and III was performed. The pathological diagnosis of hepatic angiomyolipoma was obtained.

Discussion

Variations in the predominance of the tissue components in HAML impedes diagnosis based on imaging alone. The most promising evidence of HAML is the histological identification of lipomatous, myomatous, and angiomatous tissue combined with immunohistochemical positivity for HMB-45. Although the tumour is considered benign, some cases have been described with malignant behaviour. Surgical resection should be considered in case of symptoms, inconclusive biopsy, or growth in follow-up. Other surgical indications may include aggressive patterns such as vascular invasion, p53 immunoreactivity, or rapidly proliferating tumour cells.

Conclusion

HAML is a rare liver tumour. In patients with symptoms, uncertain diagnosis, or tumour growth, surgical resection should be performed according to oncological criteria.

[Angiomyolipoma of the liver-a case report and review of the literature]

We report the case of a 70-year-old female patient with an unclear liver mass after clinical and radiological evaluation. In histopathological evaluation, we diagnosed a hepatic angiomyolipoma, which is a rare entity and belongs to the perivascular epithelioid group of tumours (PEComa). In this report, we illustrate the typical histomorphology, immunohistochemical profile and molecular changes based on the case presentation and discuss and review the current literature on hepatic angiomyolipomas. In addition, typical differential diagnostic problems are highlighted.

Angiomyolipoma of the Nasal Cavity: A Distinct Entity. A Case Report and Literature Review

Angiomyolipoma (AML) is a mesenchymal tumor commonly found in the kidneys. Extra-renal AML is uncommon and especially rare in the nasal cavity. To our knowledge, fewer than five cases of nasal AML are reported in the United States. We present a case of nasal AML in a 65-year-old man with a history of rhinosinusitis and obstruction of the left nasal cavity. The lesion comprised of admixed spindled smooth muscle cells, mature adipose tissue, and thick-walled blood vessels. Smooth muscle differentiation of the spindled cells was confirmed by expression of smooth muscle actin. Surprisingly, melanocytic markers, such as HMB45, were negative. The histologic features and immunoprofile suggest that nasal AML is pathologically distinct from neoplastic AMLs/perivascular epithelioid cell tumors (PEComas) that typically occur in the kidney. We propose that nasal AML is a hamartomatous lesion rather than neoplastic. Although AML is rare in the nasal cavity, it should be considered in the differential diagnosis of clinically benign nasal masses.

Abdominal perivascular epithelioid cell tumor (PEComa) without visible fat: a clinicopathologic and radiological analysis of 16 cases

OBJECTIVE

To retrospectively review the clinicopathological features and computed tomography (CT) and magnetic resonance imaging (MRI) findings of abdominal perivascular epithelioid cell tumor without visible fat (PEComa_wvf).

MATERIALS AND METHODS

Sixteen patients with surgically and pathologically confirmed perivascular epithelioid cell tumor without visible fat were enrolled. Their clinicopathological data and imaging findings were retrospectively reviewed. The CT and MRI features, including location, size, shape, margin, density, calcification, cystic necrosis and enhancement pattern, were analyzed.

RESULTS

There were 4 males and 12 females (median age, 46 years; range, 21-65 years) in this study. All 16 patients were diagnostic asymptomatic unenhanced CT or MRI and revealed a well-defined (n = 13), oval (n = 10), mass with heterogeneous (n = 6) or homogeneous density/signal intensity (n = 7), calcification and hemorrhage was no found in any cases. On enhanced CT/MRI, markedly enhancement patterns (n = 14) were observed. The "peripheral enhancement" sign was observed in 13 cases. One in 16 cases recurrence was discovered during the follow-up period.

CONCLUSIONS

Dynamic CT, MRI and pathology of PEComa_wvf had some characteristics of non-aggressive pattern of performance, and MRI would provide beneficial detection of microscopic fat. Enhanced imaging showed PEComa_wvf is characterized by a "peripheral enhancement" with a marked enhancement pattern. Knowing these characteristics could contribute to improving the understanding abdominal PEComa_wvf and related palliative care.

Contrast-enhanced sonographic appearances of two primary hepatic epithelioid angiomyolipomas

Epithelioid hepatic angiomyolipoma (Epi-HAML) is a rare hepatic tumor frequently misdiagnosed as hepatocellular carcinoma (HCC). Unlike conventional angiomyolipoma (AML), Epi-HAML contains minimal amount of adipose tissue, which is a radiological distinguishing feature between AML and HCC. Two patients were referred for management of incidentally found hepatic lesions confirmed to be Epi-HAML on post-resection tissue analysis. CT and MRI findings were suggestive of HCC. Contrast-enhanced ultrasound demonstrated intratumoral shunting, a feeding artery, and early draining hepatic vein. These findings should alert radiologists to the possibility of Epi-HAML. Furthermore, these features may be better assessed by contrast-enhanced ultrasound due to its superior dynamic temporal resolution.

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.

Rare MDM2 amplification in a fat-predominant angiomyolipoma

Angiomyolipomas (AMLs) are triphasic tumors (smooth muscle, vascular and adipocytic components) with myomelanocytic differentiation, arising most commonly in the kidneys, which can show predominant epithelioid morphology and fat-predominant or fat-poor variants. Fat-predominant AMLs can show areas of hypercellularity and lipoblast-like cells, and these features can mimic well-differentiated liposarcoma (WDLS). To date, only one documented metastatic epithelioid AML showed unequivocal MDM2 amplification by fluorescence in situ hybridization. We describe our findings in a series of 35 AMLs including epithelioid, fat-poor, and fat-predominant variants, following interrogation of the MDM2 locus by FISH and CISH assays. MDM2 amplification was detected in 1 fat-predominant AML. Our findings demonstrate that rare MDM2 amplifications can occur in AMLs. We favor that this finding likely represents a "molecular bystander" event since these tumors are mainly driven by aberrations in the TSC1/TSC2 genes. Nevertheless, the presence of MDM2 amplification in a fat-predominant AML could present a potential diagnostic pitfall, particularly when confronted with the differential diagnosis of fat-predominant AML and WDLS in limited material from the retroperitoneum.

Imaging hepatic angiomyolipomas: key features and avoiding errors

Hepatic angiomyolipomas (HAMLs) are rare mesenchymal neoplasms, which have highly variable imaging appearances, often leading to misdiagnosis. They belong to the family of perivascular epithelioid cell neoplasms (PEComas). HAMLs have a wide spectrum of imaging appearances due to variable amounts of smooth muscle cells, adipose tissue, and blood vessels in their makeup. Although typically sporadic, they are also associated with tuberous sclerosis. Sporadic lesions tend to be solitary whilst patients with tuberous sclerosis often have multiple HAMLs invariably accompanied by renal AMLs. Having been originally considered benign hamartomas, increasing reports of complications, including malignant behaviour, has also resulted in uncertainty in regard to their optimal management. Typically described imaging characteristics are of a hypervascular fat-containing lesion with prominent intratumoural vessels and an early draining vein; however HAMLs commonly demonstrate a paucity of fat or wash-out on contrast-enhanced imaging, and not all HAML lesions are hypervascular. HAMLs can therefore easily be misdiagnosed as other hepatic lesions, in particular hepatocellular carcinoma. This review describes the imaging characteristics of HAMLs, illustrating the wide variety of potential appearances across ultrasound, contrast-enhanced ultrasound, computed tomography, and magnetic resonance imaging, and highlights the challenges and potential errors that can be made. This review will aid radiologists in avoiding potentially major pitfalls when faced with this rare but important liver pathology.

Malignant hepatic vascular tumors in adults: Characteristics, diagnostic difficulties and current management

Malignant vascular tumors of the liver include rare primary hepatic mesenchymal tumors developed in the background of a normal liver parenchyma. Most of them are detected incidentally by the increased use of performing imaging techniques. Their diagnosis is challenging, involving clinical and imaging criteria, with final confirmation by histology and immunohistochemistry. Surgery represents the mainstay of treatment. Liver transplantation (LT) has improved substantially the prognosis of hepatic epithelioid hemangioendothelioma (HEHE), with 5-year patient survival rates of up to 81%, based on the European Liver Intestine Transplantation Association-European Liver Transplant Registry study. Unfortunately, the results of surgery and LT are dismal in cases of hepatic angiosarcoma (HAS). Due to the disappointing results of very short survival periods of approximately 6-7 mo after LT, because of tumor recurrence and rapid progression of the disease, HAS is considered an absolute contraindication to LT. Recurrences after surgical resection are high in cases of HEHE and invariably present in cases of HAS. The discovery of reliable prognostic markers and the elaboration of prognostic scores following LT are needed to provide the best therapeutic choice for each patient. Studies on a few patients have demonstrated the stabilization of the disease in a proportion of patients with hepatic vascular tumors using novel targeted antiangiogenic agents, cytokines or immunotherapy. These new approaches, alone or in combination with other therapeutic modalities, such as surgery and classical chemotherapy, need further investigation to assess their role in prolonging patient survival. Personalized therapeutic algorithms according to the histopathological features, behavior, molecular biology and genetics of the tumors should be elaborated in the near future for the management of patients diagnosed with primary malignant vascular tumors of the liver.

Hepatic angiomyolipoma with early drainage veins into the hepatic and portal vein

Hepatic angiomyolipoma (AML) is a rare stromal tumor composed of variable admixtures of thick-walled vessels, smooth muscles and adipose tissue. One of the specific radiological findings of hepatic AML is an early drainage vein noted via enhanced computed tomography (CT). We report a case of hepatic AML showing early drainage veins into both the hepatic and portal vein. The case involved a 46-year-old woman who was referred to our hospital because of a giant hepatic tumor. CT revealed well-enhanced 14 cm and 1 cm tumors in the left and right lobes, respectively. Magnetic resonance imaging demonstrated the existence of adipose tissues in the larger tumor. Hepatic arteriography revealed early drainage veins draining into both the hepatic and portal vein. Based on a diagnosis of hepatic AML, left hepatectomy and partial hepatectomy were performed. Pathology revealed both tumors as hepatic AML based on human melanoma black-45 immuno-positivity. Hepatic AML with early drainage veins into both the hepatic and portal vein is rare. The dilated and retrogressive vein drains the abundant arterial blood flow of the tumor. The finding of early drainage veins into not only the hepatic vein but also the portal vein should be helpful for diagnosing hepatic AMLs.

Imaging of Unusual Renal Tumors

PURPOSE OF REVIEW

Renal masses are a wide entity and a common finding in clinical practice. Detection of these masses has increased in the last years, yet mortality rates have slightly decreased.

RECENT FINDINGS

According to the World Health Organization classification, there are 8 types, 51 subtypes, and a lot more subsequent subclassifications of renal tumors. Histopathological analysis should always be assessed for final diagnosis of theses tumors. However, imaging can be an important diagnostic guidance. The most common diagnoses of renal tumor are clear cell carcinoma, papillary renal cell carcinoma, angiomyolipoma, and transitional cell carcinoma. Nonetheless, a considerable variety of particular tumors can arise from the kidney, challenging the expertise of radiologists and urologists on this subject. The awareness of these unusual entities is vital for professionals working at a complex medical facility with greater volume of patients. We hereby present uncommon renal tumors and its pathological and radiological features.

Hepatic myomatous angiomyolipoma diagnosedpreoperatively from specific imaging features: A case report

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An extremely rare case report of hepatic myomatous angiomyolipoma.

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Including specific imaging features to diagnose with hepatic angiomyolipoma.

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There is a significant interesting imaging findings of hepatic myomatous angiomyolipoma.

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Previous reports only revealed the pathological findings and a few imaging findings, however we show two specific features of imaging with rare pathological findings.

Introduction

Hepatic angiomyolipoma is a rare tumour and is difficult to obtain the accurate diagnosis preoperatively because the imaging features are similar to hepatocellular carcinoma.

Presentation of Case

We present a case study of an 80-year old woman with a liver tumour measuring 6.2 cm × 6.0 cm. We were able to diagnose the tumour preoperatively as a rare hepatic myomatous angiomyolipoma based on the presence of early venous return evident on angiography and small low-intensity areas corresponding to fat within the tumour revealed by out-of-phase EOB-MRI. The tumour was removed by minimally invasive surgery and our preoperative diagnosis was confirmed by positive immunoreactivity for both angiomyolipoma-specific human melanoma black 45 and smooth muscle cell positivity for melanin.

Discussion

We consider that the information obtained in this case will be useful for preoperative diagnosis of other hepatic angiomyolipomas, thus facilitating more appropriate and less invasive surgery and improving the overall outcome.

Conclusion

Hepatic myomatous angiomyolipoma is a rare tumour. We illustrated the two specific imaging features to diagnose it preoperatively.

Giant hepatic angiomyolipoma: a case report

Hepatic angiomyolipoma (AML) is a rare mesenchymal tumour with an undetermined malignant potential. Clinical symptoms are non-specific. The radiological hallmarks are high vascularization of lesion and presence of macroscopic fat. The proportion of fatty tissue varies significantly and discrepancies between pre-operative imaging and histological findings are observed in more than 50% of cases. Visualization of the draining vein may aid in differentiation between AML and hepatocellular carcinoma with abundant fatty component. Biopsy is indicated in ambiguous cases. Presence of clinical symptoms warrants surgical treatment. We present a clinical case of giant hepatic AML, discuss its typical features and treatment options.

CT features of hepatic epithelioid angiomyolipoma: differentiation from hepatocellular carcinoma in patients with noncirrhotic livers

Background

Hepatic epithelioid angiomyolipoma (HEA) shares some similarities with other hepatic tumors, such as hepatocellular carcinoma (HCC). Thus, establishing a definite diagnosis of HEA based on medical imaging is often difficult. In this study, we evaluated multiphasic computed tomography (CT) imaging to differentiate HEA from HCC in patients with noncirrhotic livers.

Methods

We retrospectively analyzed the clinical and imaging data of both contrast and non-contrast enhanced CT scans from 25 patients with HEA and 50 patients with HCC in noncirrhotic livers. CT features, including lesion position, size, shape, interior content, border, enhancement degree, and enhancement pattern, were independently evaluated by two radiologists. Intratumoral blood vessels, peripheral supply vessels, the early display of the hepatic vein, peripheral abnormal perfusion, peripheral washout sign, pseudocapsule, and portal tumor thrombus were also evaluated. Next, we quantitatively analyzed difference within results of clinical and CT characteristics between the HEA and HCC groups.

Results

The number of female HEA patients is more than male (76% vs. 24%), with a mean age of 49.44±10.33 years (from 30 to 68 years). The majority (64%) of HEA patients were asymptomatic, without hepatitis (88%). On non-contrast enhanced CT, HEA mainly manifested as a round (92%), hypodense mass (100%) with little fat (12%) and rare complications, such as hemorrhage (4%) and calcification (4%). HEA all manifested as an intensely enhanced mass on contrast-enhanced CT. The differences between HEA and HCC were significant in the imaging characteristics of the early display of the hepatic vein (32% vs. 0%, P=0.000), intratumoral blood vessels during the nonarterial phase (36% vs. 8%, P=0.003), washout enhancement (52% vs. 86%, P=0.001), and prolonged enhancement (40% vs. 4%, P=0.000).

Conclusions

Although HEA is an uncommon hepatic tumor, clinical and CT manifestation may be indicative. Clinical and CT characteristics including asymptomatic, non-hepatic, fat-deficient, early display of the hepatic vein, intratumoral blood vessels during the nonarterial phase and prolonged enhancement are selected to improve the recognition of HEA, supporting for a differential diagnosis from HCC.

Angiomyolipoma of the Liver: A Rare Benign Tumor Treated with a Laparoscopic Approach for the First Time

BACKGROUND/AIM

Epithelioid angiomyolipoma of the liver is a rare benign mesenchymal tumor that usually presents in adult female patients. It most frequently occurs in the kidney, with the liver being the second most common site of involvement. Angiomyolipoma belongs to a family of tumors arising from perivascular epithelioid cells, but in rare cases may also have cystic features. We report our experience via the first case of hepatic angiomyolipoma treated by laparoscopic approach.

PATIENTS AND METHODS

We present the case of a 50-year-old female patient complaining of abdominal pain. Abdominal ultrasound (US) and Magnetic Resonance Imaging (MRI) revealed a 5 × 3 cm mass located in the left liver lobe. The tumor was resected with a laparoscopic approach. Microscopic examination of the tumor revealed hepatic angiomyolipoma.

RESULTS

Twenty-seven months postoperatively, the patient remains fit and healthy.

CONCLUSION

Angiomyolipoma can be removed by laparoscopy.

Malignant potential of epithelioid angiomyolipomas of the liver: A case report and comprehensive review of the literature

Hepatic epithelioid angiomyolipoma (HEAML) is a rare mesenchymal tumor that has been reported to have malignant potential. We herein describe a rare case of atypical HEAML. A 43-year-old Caucasian male patient visited his general practitioner due to a productive cough persisting for >2 months. During evaluation with several imaging tests, a chest computed tomography (CT) incidentally revealed a well-demarcated lesion in the caudate lobe of the liver, sized 7 cm. An abdominal magnetic resonance imaging examination confirmed the findings of the CT. The possibility of hepatocellular carcinoma at that time could not be excluded. Due to inconclusive cross-sectional imaging, the patient underwent left hepatectomy with additional resection of segment I. The patient's postoperative course was uneventful. A diagnosis of 'atypical' HEAML was established in the present case. The majority of HEAMLs are considered to be benign, although there are several reported cases exhibiting malignant behavior, such as tumor growth, presence of atypical cells, recurrence after surgical resection, metastasis and invasive growth into the liver parenchyma and alongside the vessels. From 2000 onwards, 19 cases of malignant hepatic AML have been reported. Malignant transformation is considered to occur mostly in the epithelioid subtype. To that end, when epithelioid or atypical characteristics are identified on preoperative biopsy, resection is indicated due to the high probability of malignancy.

Case Report of a Hepatic Angiomyolipoma

Angiomyolipoma (AML) is a benign mesenchymal tumor that has been frequently reported in the kidney but rarely in the liver. Hepatic AML may be clinically, radiologically and morphologically difficult to distinguish from hepatocellular carcinoma or other hepatic lesions, even though the number of cases has been increasing recently due to improved imaging techniques. Histologically it consists of smooth muscle cells, adipose cells and abnormal blood vessels. It is commonly diagnosed following abdominal pain but may also be asymptomatic, has a predominant female predilection, highly variable size and occurs in subjects with a wide age range. The right lobe is the most common site, and multicentricity has been reported. Here we report a case of the myomatous variant of AML, accidentally discovered in a young woman with no clear features on radiographic examination, which was diagnosed by means of fine needle aspiration biopsy (FNAB) and then surgically removed. Although careful observation with serial radiological follow-up is an option in these cases, we chose the surgical approach because of the risk of rupture due to the large size of the lesion and the risk of malignant behavior or transformation. In case of the myomatous variant composed of irregular cells with epithelioid appearance, hepatocellular carcinoma with fatty changes or the possibility of other malignant tumors must be ruled out by immunohistochemistry (HMB-45), even in biopsy specimens.

Hepatic angiomyolipoma: mutation analysis and immunohistochemical pitfalls in diagnosis

AIMS

Hepatic angiomyolipoma (AML) often shows epithelioid morphology with inconspicuous fat. Epithelioid component can mimic hepatocellular adenoma (HCA) or carcinoma (HCC). The aims of this study were to examine the expression of commonly used markers for HCA or HCC in hepatic AML and highlight pitfalls in diagnosis.

METHODS AND RESULTS

Resected hepatic AMLs (n = 16) were reviewed; reticulin stain, immunohistochemistry for glutamine synthetase (GS), β-catenin and liver fatty acid binding protein (LFABP) were performed along with Sanger sequencing of exon 3 of CTNNB1 and next-generation sequencing (NGS). Predominant epithelioid component (≥50%) was seen in 80% of cases. Foamy macrophage was present in 33% of cases. High-risk histological features were often present in tumours with benign outcome: marked atypia (19%), mitoses (20%) and necrosis (33%). GS staining (≥10% of tumour) was seen in epithelioid components in 13 (87%) cases, and was diffuse (>50% of tumour) in six (40%) cases. LFABP staining or nuclear β-catenin staining was not seen in any case. Sanger sequencing and NGS did not reveal CTNNB1 mutation in any tested case. NGS demonstrated TSC2 mutations in all five cases tested.

CONCLUSIONS

The predominance of epithelioid component resembling HCA or HCC is common in hepatic AML. Absence of LFABP and presence of fat can be mistaken for HNF1α-inactivated HCA. Diffuse GS staining can be mistaken for β-catenin-activated HCA or HCC. Diffuse GS expression is not related to CTNNB1 mutation. All tested cases showed TSC2 mutation, supporting this as the driving genetic event for hepatic AML.

Fat-Containing Liver Lesions on Imaging: Detection and Differential Diagnosis

OBJECTIVE

The purpose of this article is to review how fat is detected on imaging and to discuss the differential diagnosis of fat-containing liver lesions.

CONCLUSION

Fat is a highly useful feature in characterizing liver lesions on imaging. Although a variety of liver lesions can show fat on cross-sectional imaging, the presence of fat usually indicates that the lesion is of hepatocellular origin. Less commonly, nonhepatocellular fatty lesions may be distinguished by ancillary clinical and imaging features.

Immunohistochemistry in the Diagnosis of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) can be difficult to distinguish from its mimics, including metastatic tumor, benign hepatocellular lesion, and high-grade dysplastic nodule, especially when limited biopsy material is available. Hence, the judicious use of immunohistochemical stains is necessary to establish a correct diagnosis. This article describes advantages and disadvantages of immunohistochemical markers that are most commonly used to distinguish between these lesions. Diagnostic workup of malignant liver mass (HCC and its histologic variants vs metastatic tumor) as well as well-differentiated hepatocellular lesion (well-differentiated HCC vs focal nodular hyperplasia vs hepatocellular adenoma) is also discussed.

Primary perivascular epithelioid cell tumors of the liver: CT/MRI findings and clinical outcomes

OBJECTIVES

The purpose of our study was to describe the CT and MRI features of primary PEComas of the liver and to document the associated clinical outcomes.

METHODS

Retrospective study included 20 patients with primary hepatic perivascular epithelioid cell tumors (PEComa) with pathology and clinical outcomes for correlation.

RESULTS

Study group included 20 patients: 16 women, 4 men; mean age 53 (range 35-77) years. Initial pathology diagnoses were classic angiomyolipoma (AML) (n = 11), epithelioid AML (n = 7), and PEComa not otherwise specified (n = 2). Mean tumor size was 5.1 (range 1.3-15.0) cm. CT/MRI features included well-defined margins 20/20 (100%), arterial enhancement 18/19 (95%), subcapsular location 17/20 (85%), heterogeneous 16/20 (80%), dysmorphic vessels 14/20 (70%), fat 13/20 (65%), hemorrhage 4/20 (20%), cystic components 4/20 (20%), and calcification 1/20 (5%). At the time of discovery, 18 patients were asymptomatic and their tumors were incidentally detected on imaging, and 2 patients were symptomatic. Ultimately, 18 tumors were benign and 2 developed metastases.

CONCLUSIONS

On CT/MRI, most primary hepatic PEComas were well-defined, arterial enhancing, subcapsular, heterogeneous masses that often had dysmorphic vessels and contained fat. Most tumors were benign but complications included local symptoms, bleeding, and malignant change.

A case of ruptured hepatic angiomyolipoma in a young male

A 31-year-old male visited a local hospital due to sudden-onset severe abdominal pain. Abdominal computed tomography revealed a solid cystic mass with a size of approximately 12 cm and exhibiting both hemorrhage and fluid collection in the pelvic cavity. Emergency angiography and embolization were performed, and a large hepatic tumor was subsequently surgically resected. The tumor cells stained positive for human melanoma black-45 and smooth-muscle actin, and the pathologic diagnosis was hepatic angiomyolipoma. This case report also discusses the spontaneous rupture of a hepatic angiomyolipoma.

Challenge of FNA diagnosis of angiomyolipoma: A study of 33 cases

BACKGROUND

Angiomyolipoma (AML), typically composed of smooth muscle, vessels, and fat, is generally a benign tumor in the kidneys. However, it occasionally occurs in extrarenal sites and behaves like a malignant tumor. AML is uncommonly encountered in fine-needle aspiration (FNA) samples and can cause diagnostic difficulty.

METHODS

We searched our pathology database for FNA cases diagnosed between 2003 and 2015 that were subsequently confirmed to be AML in the same lesion by surgical pathologic evaluation. The diagnostic performance, challenges, and cytologic features were retrospectively reviewed.

RESULTS

In total, 33 FNA cases from 31 patients were identified. The final surgical pathologic diagnoses included 30 primary AMLs (28 in kidneys and 2 in liver) and 3 were metastases (in liver, lung, and abdominal wall, respectively). Aspiration sites included kidney/retroperitoneum (n = 28), abdominal wall (n = 1), lung (n = 1), and liver (n = 3). The FNA diagnoses were consistent with/favor AML (n = 16), descriptive (n = 12), nondiagnostic (n = 2), and erroneous (n = 3). Of the 3 erroneous cases, 2 were diagnosed as renal cell carcinoma, and 1 was diagnosed as a pleomorphic malignant neoplasm. Cytologically, cases with predominantly spindle cells were the most commonly encountered (n = 19). Cases with predominantly epithelioid cells (n = 6) can pose a diagnostic difficulty and were observed in all 3 metastatic AMLs and in 2 of the 3 erroneous cases. Immunostains were performed on 11 FNAs and helped the diagnosis in 9 cases.

CONCLUSIONS

FNA diagnosis of AML may be challenging, especially in cases with a predominantly epithelioid component and/or an extrarenal location. Immunostaining is important to improve diagnostic accuracy of this rare entity. Cancer Cytopathol 2017;125:257-266. © 2016 American Cancer Society.

Immunohistochemical approach for the diagnosis of a liver mass on small biopsy specimens

Well-differentiated hepatocellular carcinoma (HCC) shares overlapping histological features with benign hepatocellular lesions, including hepatocellular adenoma and focal nodular hyperplasia in non-cirrhotic liver, and with high-grade dysplastic nodule in cirrhotic liver. Several metastatic tumors, such as neuroendocrine tumor, renal cell carcinoma, adrenocortical carcinoma, melanoma, and epithelioid angiomyolipoma, can be indistinguishable from HCC on histologic grounds. Since this distinction has important therapeutic implications, judicious use of immunohistochemical markers plays an important role in establishing an accurate diagnosis, especially when limited material of tumor is available on cell block or a small core biopsy. This review describes commonly used immunohistochemical markers used in the diagnosis of HCC, highlighting advantages and disadvantages of each marker, and suggests appropriate immunohistochemical panels for specific clinicopathologic situations.