Hepatic angiomyolipoma with trace amounts of fat: a case report and literature review

Hepatic Angiomyolipoma With Predominant Lipomatous Component: A Rare Entity

Hepatic angiomyolipoma (HAML) is a rare benign mesenchymal tumor with varying amounts of mature adipose tissue, smooth muscle cells, and thick-walled blood vessels. We present a rare case of hepatic angiomyolipoma (AML) with predominant lipomatous components. A 42-year-old female presented to the hospital with pain in the right lumbar region. On imaging, there was a large fat-predominant mass attached to the surface of the liver extending down to the lumbar region. On small biopsy, it was reported as a well-differentiated adipocytic neoplasm, and fluorescence in situ hybridization (FISH) studies performed for MDM2 were negative. On excision, histopathological examination showed predominantly fat components, but there were few epithelioid cells between adipocytes and thick-walled blood vessels. These cells were positive for Melan-A, HMB45, and smooth muscle actin (SMA) and negative for hepatocyte paraffin-1 (Hep Par1). Angiomyolipoma is a benign tumor and has a good prognosis with surgical excision. Few cases are associated with tuberous sclerosis.

[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.

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.

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.

A Case of Exophytic Angiomyolipoma of the Liver

Hepatic angiomyolipoma (AML) is a benign liver tumor, composed mainly of blood vessels, smooth muscle, and fat cells in varying proportions. We report on a case of resected hepatic AML which was diagnosed preoperatively using contrast-enhanced computed tomography scan.

Hepatic angiomyolipoma: clinical, imaging and pathological features in 178 cases. Med Oncol. 2013;30:416. [PMID: 23292871 DOI: 10.1007/s12032-012-0416-4]

The aim of the study was to review the main clinical, imaging and pathological features of hepatic angiomyolipoma (HAML). We retrospectively analyzed the imaging, pathological and clinical features of 178 patients who underwent surgical resection for HAML. Forty-three males and 135 females with a median age of 43.5 years (range: 17-76 years) were enrolled in the study. Routine blood tests, including those for α-fetoprotein, carcinoembryonic antigen, and carbohydrate antigen determinant, were normal. Liver function was classified as Child-Pugh A for all patients. Twenty-one patients were positive for hepatitis B surface antigen (HBsAg), while two had liver cirrhosis. Seventy-five lesions were located in the right hepatic lobe, 42 in the left hepatic lobe, 12 in the hepatic caudal lobe, and 49 in both left and right lobe. All patients underwent examination by ultrasound sonography (US), and additional examinations by computed tomography (CT) and magnetic resonance (MR) were carried out for 115 and 81 patients, respectively. Various diseases including HAML, liver cancer, liver hemangioma, hepatic lipoma, hepatic hamartoma, focal nodular hyperplasia and liver adenoma were diagnosed before operation. CT and MRI are more conclusive than US (US vs CT: χ(2) = 17.72, P = 0.00; US vs MRI: χ(2) = 12.14, P = 0.00), but for the sensitivity of these three imaging modalities, MRI performs the best (US vs MRI: χ(2) = 5.938, P = 0.015; CT vs MRI: χ(2) = 2.544, P = 0.111). All the patients underwent liver resection (96 right hepatic lobectomy, 41 left hepatic lobectomy and nine caudal lobe hepatic lobectomy). Several sampled tissues were positive for HBsAg (21/168, 12.5 %), β-catenin (4/41, 9.8 %), CD-34 (119/165, 72.1 %), HMB-45 (162/169, 92.9 %), SMA (145/158, 91.8 %) and vimentin (20/27, 74.1 %). The diagnosis of HAML remains difficult and mainly relies on pathological findings. For the imaging modalities, we recommend MRI examination because of its better definition and sensitivity. Although HMB-45 is considered the main histopathological biomarker for HAML, SMA may be also helpful in the diagnostic process (HMB-45 vs SMA: χ(2) = 2.37, P = 0.123). When the diagnosis of HAML is suspicious or hypothesized, surgical resection remains the recommended strategy due to the difficulty in diagnosis preoperatively and the potentially invasive growth of the lesion.

Angiomyolipoma of the liver: analysis of typical features and pitfalls based on own experience and literature

We present imaging findings (ultrasound, computed tomography, and magnetic resonance imaging) of eight patients with hepatic angiomyolipoma (HAML). The lesions were solitary in seven patients, and one patient had multiple tumors (n=11). Angiomyolipoma, even though a rare liver tumor, should be included in the differential diagnosis in cases of highly vascularized lesion containing a significant amount of fat. Suggestion of the diagnosis of HAML might be helpful for the pathologist in the selection of the typical histochemical staining of the tumor, allowing accurate diagnosis, which, in turn, determines the implementation of appropriate therapeutic intervention.

A case of hepatic angiomyolipoma difficult to distinguish from hepatocellular carcinoma

We report a case of hepatic angiomyolipoma with uncommon clinical features. A 56-year-old man presented with a hepatic tumor in the caudate lobe. The tumor was hypoechoic on ultrasonography, showed early-phase hyperattenuation on enhanced computed tomography and did not absorb iron on superparamagnetic iron oxide-enhanced magnetic resonance imaging. Hepatocellular carcinoma was highly suspected, and the patient underwent hepatic resection. Histologically, the tumor was mainly composed of smooth muscle cells and contained small amounts of adipose cells and blood vessels. On immunohistochemical staining, the smooth muscle cells were positive for a melanocytic cell-specific monoclonal antibody. In cases with uncommon features of angiomyolipoma, it is quite difficult to distinguish angiomyolipoma from hepatocellular carcinoma.

Hepatic angiomyolipoma

Hepatic angiomyolipoma is a rare, benign, hepatic mesenchymal neoplasm found in both males and females, and most commonly in adult females. Angiomyolipoma occurs most commonly in the kidneys. The liver represents the second most frequent site of involvement. Hepatic angiomyolipomas are composed of varying amounts of smooth muscle cells, adipose tissue, and vessels. The smooth muscle cell component is the most specific to the diagnosis. The smooth muscle cells can have varying morphologies and are positive for homatropine methylbromide-45 but are negative for hepatocyte paraffin 1 and S100 protein. The definitive diagnostic study remains the histologic examination of the surgically resected lesion coupled with immunohistochemical stains. The differential diagnosis includes hepatocellular carcinoma, hepatic adenoma, leiomyoma, hepatoblastoma, melanoma, and gastrointestinal stromal tumor. The immunohistochemical staining pattern differentiates this lesion from other malignant and benign liver lesions. If the diagnosis of hepatic angiomyolipoma has been made, it can be followed conservatively or surgically resected.

Hepatic angiomyolipoma: a retrospective study of 25 cases

PURPOSE

We report our experience of diagnosing and treating hepatic angiomyolipoma (HAML), a rare benign mesenchymal tumor.

METHODS

We analyzed retrospectively the clinicopathologic, radiological, and operative data of 25 patients who underwent surgery for HAML at our institute between November 2001 and May 2006.

RESULTS

Most patients (20/25) were asymptomatic and had normal liver function. Ultrasonography (US) showed a heterogeneous hyperechoic mass in 13 of 23 patients, precontrast computed tomography (CT) showed that all of 12 lesions scanned were hypodense, and magnetic resonance imaging (MRI) showed hypointensity on T1-weighted images and hyperintensity on T2-weighted images in most (5/6) lesions. Marked enhancement in the arterial phase was seen in 10 of 12 lesions on CT scans and in 6 of 6 lesions on MRI scans. All tumors were composed of varying proportions of smooth muscle, adipose tissue, and blood vessels, and showed positive immunohistochemical staining for HMB-45. All patients underwent partial hepatectomy and there was no evidence of recurrence after a median follow-up of 43 months.

CONCLUSION

The radiological features of HAML vary according to its histological components. The definitive diagnosis of HAML is challenging and depends on the presence of HMB-45-positive myoid cells. Hepatic angiomyolipoma is treated effectively with surgery and the prognosis is good.