Imaging characteristics of large lipoma and angiomyolipoma of the liver. Case reports

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.

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.

Angiomyolipoma of the Liver

Angiomyolipoma, a rare benign liver tumor, was observed in a 50-year-old woman examined with US, CT, MR imaging and angiography. Dynamic studies using CT and MR imaging were valuable in differentiating the disease from hepatocellular carcinoma with fat deposits.

Multiple angiomyolipomata of the liver: a case report

Angiomyolipoma (AML) is a rare benign tumor that occurs most commonly in the kidney. Occasionally it may be found in the liver. Lesions in the liver are usually solitary. Multiple AMLs are extremely rare and are typically seen in patients with tuberous sclerosis. We now report an unusual case of a 46-year-old woman with multiple hepatic AMLs. There were more than 15 lesions distributed predominantly in the right hepatic lobe. The tumors ranged from 0.2 to 6 cm in size and consisted of a variable admixture of proliferating blood vessels, adipose tissue, and smooth muscle. There was no clinical evidence of tuberous sclerosis in this patient. Polymerase chain reaction amplification of the highly polymorphic human androgen receptor gene (HUMARA) was performed and the pattern of X chromosome inactivation was analyzed. Three of the five representative AML nodules showed a preferential loss of one of the two HUMARA alleles indicating a clonal proliferation with involvement of different alleles. Histologic examination of the corresponding lesions showed clonal lesions to be predominantly composed of epithelioid myoid cells while the polyclonal lesions were predominantly composed of adipose tissue. While the histologic diagnosis of AML in a surgical resection specimen is often straightforward, the radiographic, cytologic and intra-operative interpretation of a case with multiple lesions presents a considerable challenge.

Hepatic angiomyolipoma: various appearances on two-phase contrast scanning of spiral CT

The purpose of this study was to describe and analyze the various appearances of hepatic angiomyolipoma (AML) on the two-phase contrast scans of spiral CT and find out the valuable signs suggesting the diagnosis. Spiral CT scanning of pre- and post-contrast arterial phase, portal venous phase were performed in 12 cases. We found that 11 of 12 lesions appeared as hypodense, the other one appeared as slightly hyperdense on pre-contrast CT scans. On the arterial phase, 11 lesions were markedly enhanced, with the central vasculature opacification in eight lesions; the only other lesion showed no marked enhancement, but with massive vessels seen within the lesion. On the portal venous phase, eight lesions remained in enhancement with the central vessels also seen in six lesions. Our results revealed that two-phase contrast scanning could demonstrate some characteristic features of AML, such as fat components within the lesions, hypervascular tumors, the absence of capsule. Especially the central vessels within the lesions suggested strongly the diagnosis of AML. As for atypical cases, the diagnosis remained difficult and should be differentiated from other hypervascular lesions by means of other imaging modalities or needle puncture biopsy.

Angiomyolipoma of the liver: significance of CT and MR dynamic study

Angiomyolipoma is a benign mesenchymal tumor that has been reported frequently in the kidney but rarely in the liver. In the present study, we present four cases of hepatic angiomyolipoma with different radiologic appearances, discuss differential diagnosis, and review previously reported cases. One of our cases was followed for 8 years. Computed tomography (plain, enhanced, and dynamic study), magnetic resonance imaging (T1-weighted spin echo, T2-weighted spin echo, and dynamic study), ultrasonography, and angiography were performed in all cases. Although different radiologic appearances were observed in the tumors, based on different proportions of fat, blood vessels, and muscle, three cases were diagnosed as angiomyolipoma. In one case, it was quite difficult to make radiologic diagnosis; hepatocellular carcinoma with fatty metamorphosis in part was most likely suspected, but histopathological examination revealed angiomyolipoma with few fat elements. In the present study, early and prolonged enhancement of the lesion with the special pattern of time density/intensity curve was significant for angiomyolipoma, and we suggest that preoperative radiologic diagnosis of the lesion is possible in most of the cases. However, it can be quite difficult to distinguish angiomyolipoma from some hepatocellular carcinomas with fatty metamorphosis.

Hepatic angiomyolipoma developing during the follow-up of ulcerative colitis: report of a case and review of the literature

Hepatic angiomyolipoma is a rare tumor composed of spindle-shaped and epithelioid smooth muscle cells, adipose tissue, and proliferating blood vessels. We report the first documented case of this tumor developing in a patient with ulcerative colitis. A solitary tumor (7.5 x 7.5 x 7 cm) was detected in the left lateral segment of the liver and a left hepatic lobectomy was performed. The diagnosis of angiomyolipoma was confirmed by a pathological examination. We also review the literature on previously reported cases of hepatic angiomyolipoma.

Hepatic angiomyolipoma: value of proton (fat/water) chemical shift fast low angle shot (FLASH) MR imaging technique in detecting fatty tissue content

A case of angiomyolipoma of the liver in a 43-yr-old woman is reported. Findings on ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging techniques are presented and the usefulness of proton (fat/water) chemical shift FLASH imaging to confirm the presence of intratumoral fat is pointed out.

A case of huge solitary angiomyolipoma of the liver

A 32-year-old male patient, diagnosed as a hepatic solitary angiomyolipoma post-operatively, is reported. The tumor was well definedly inhomogenous fat density mass on ultrasonography, computerized tomography (CT) and magnetic resonance imaging (MRI). The lesion was hypervascular on arteriography. The diagnosis was confirmed by an extended right lobectomy and histological examination.

Liver angiomyolipoma: classic and unusual presentations

Two cases of liver angiomyolipoma (AML) are presented. The first case has the classical imaging findings previously reported. The second case has no fat content on the various imaging modalities. AML should probably be included in the differential diagnosis of any hypervascular lesion of the liver. Preoperative diagnosis with core biopsy is possible.

Angiomyolipomas of the liver in tuberous sclerosis

Although the association of tuberous sclerosis and renal angiomyolipomas is well established, the occurrence of hepatic hamartomatous lesions in this disease is less well documented. We describe two cases of tuberous sclerosis with associated multiple intrahepatic angiomyolipomas, and we review the literature on this subject. Radiologically, angiomyolipomas can range from entirely lipomatous to completely solid, features which are present in our cases. A characteristic finding of the hepatic involvement in this disease appears to be the multiplicity of the lesions. We suggest that in the setting of tuberous sclerosis it is reasonable to assume that intrahepatic lesions represent angiomyolipomas. However, in nontuberous sclerosis patients with similar findings malignancy cannot be excluded.

Preoperative diagnosis of angiomyolipoma of the liver

We experienced a case of surgically proven hepatic angiomyolipoma, a rare primary benign lipomatous tumor, which was preoperatively diagnosed by defining of its characteristic histologic components and benign radiologic nature with various imaging modalities. It was the first case that full radiologic evaluation was taken and internal vascular proliferation was defined by using dynamic bolus computed tomography (CT) prior to angiography.

Angiomyolipoma of the liver: a collective review

This review summarizes the clinical and pathological findings of 52 cases of hepatic angiomyolipoma to discern and establish the most pertinent clinical and pathologic characteristics of the tumor. The disease was symptomatic in 60% of the patients. Abdominal pain or distress was the most common symptom, appearing in 37% of the patients, followed by malaise and upper abdominal mass or hepatomegaly. Of the 52 patients, only three (5.8%) showed associated tuberous sclerosis. Antemortem diagnosis of the tumor has been made with increasing frequency with the recent advent of computed tomography (CT) and ultrasound (US). The tumor was usually visualized as a hyperechoic mass by US imaging and as a low density mass less than -20 Housefield units by CT, and was hypervascular on angiography. The tumor was usually yellow to light tan, depending on the amount of fat tissue. Histologically, the tumor was characterized by an admixture of mature fat cells, blood vessels, and smooth muscle cells, with occasional foci of extramedullary hematopoiesis. The amount of smooth muscle component varied and often exhibited hypercellularity, pleomorphism with occasional bizarre giant cells, and moderate motitic activity. These features are considered conducive to an erroneous diagnosis of malignant tumor. However, since no malignant counterpart has been reported, it can easily be accurately differentiated histologically, if one is aware of the entity and can identify the three components of the tumor; blood vessels, smooth muscle cells, and fat. With regard to the histogenesis of angiomyolipoma, primitive mesenchymal cells around blood vessels may be the precursor cells.

Small angiomyolipoma of the liver diagnosed by fine-needle aspiration biopsy under ultrasound guidance

The first reported case of small hepatic angiomyolipoma to be diagnosed by fine-needle aspiration biopsy (FNAB) is described. A 53 year old man presented with a tumour in segment VI of the liver measuring 0.9 x 0.8 cm. The tumour was hyperechoic on ultrasound examination, showed relatively low density (+ 33 Hounsfield units) on computed tomography (CT), and was hypervascular on angiography. Computed tomography during arterial portography demonstrated a perfusion defect. Magnetic resonance imaging (MRI) revealed high intensity by both T1- and T2-weighted imaging. Diagnosis could not be obtained by these imaging modalities, but it was established successfully by FNAB under ultrasound guidance. Histologically, the tumour was an angiomyolipoma made up of three components: blood vessels, smooth muscle and fatty tissue. Surgery is unnecessary for this benign condition, and the patient has been followed up. Ten months later, the patient is currently doing well without growth of the hepatic angiomyolipoma.

Hepatic angiomyolipoma pre-operatively diagnosed by imaging

An asymptomatic patient with pre-operatively diagnosed solitary angiomyolipoma is reported. The tumour was a well defined, fat density mass on computerized tomography (CT) and magnetic resonance imaging (MRI), and a hyperechoic nodule with a sharp margin on ultrasonography (US). The lesion was hypervascular on arteriography and CT during hepatic angiography. Chemical shift MRI confirmed the fat component within the lesion. Although a review of the literature shows this tumour to be rare and difficult to differentiate from a malignant lesion pre-operatively, the pre-operative diagnosis of angiomyolipoma is considered feasible when the characteristic findings as described here are present.

Hepatic angiomyolipoma with striated granules and positivity with melanoma--specific antibody (HMB-45): a report of two cases

Angiomyolipoma occurs rarely in the liver, with only 25 previous cases being reported in the English literature. The article describes two additional cases, one of which was multicentric, with results of ultrastructural and immunocytochemical studies. Many of the tumor cells contained numerous electron-dense granules, some with transverse striations like those found in melanosomes. Both tumors stained positively for S-100 protein and melanoma-specific antibody HMB-45. One case also expressed vimentin and neuron-specific enolase. Both were negative for cytokeratin, carcinoembryonic antigen, alpha-fetoprotein, desmin, muscle-specific actin, factor VIII antigen, and chromogranin. Comparison of our ultrastructural findings with those of classic renal angiomyolipoma raises the possibility that the melanosomelike structures may represent renin granules rather than melanosomes, although the latter are not excluded. Expression of HMB-45 in angiomyolipoma has important biologic and diagnostic implications, whether or not it reflects melanocytic differentiation.

Angiomyolipoma of the liver: immunohistochemical study of a case

Angiomyolipoma, a not uncommon tumor of the kidney, is rarely encountered in the liver. We report a case of angiomyolipoma of the liver in a 68-year-old woman, in which immunohistochemical study was performed.

Angiomyolipoma of the vagina

An angiomyolipoma arising in the vaginal apex and presenting as a pelvic mass is reported and compared with other reported cases of extrarenal angiomyolipoma. This case appears to be the second case of angiomyolipoma arising in the vaginal wall.

An electron microscopic study of hepatic angiomyolipoma

Three cases of hepatic angiomyolipoma, each composed of an intimate mixture of numerous abnormal blood vessels and various-sized fat, spindle and/or epithelioid cells, are presented along with the findings of an electron microscopic study. The spindle cells were confirmed to be smooth muscle by immunohistochemical staining for desmin and by their ultrastructural characteristics. The mature fat cells, smooth muscle cells, immature short spindle cells apparently intermediate or transitional between the former two cell types, and the epithelioid cells were observed adjacent to the endothelial cells. Ultrastructurally, the epithelioid cells were characterized by unusual cytoplasmic organelles such as myofilaments having focal densities and dense attachments, numerous large electron-dense bodies, and a large number of glycogen particles and lipid droplets. Therefore, it is considered that the immature short spindle and epithelioid cells in hepatic angiomyolipoma might be primitive mesenchymal cells having an ability to differentiate toward both smooth muscle and fat cells.

Angiomyolipoma of the spermatic cord: case report and literature review

A case of an extrarenal angiomyolipoma in the spermatic cord is presented. Angiomyolipomas are uncommon tumors usually found in the kidney. The common embryological origin of kidney and cord structures offers a theoretical basis for the occurrence of such a neoplasm at this remote site. Complete wide excision is curative and recurrences are infrequent.