US power Doppler of hepatic angiomyolipoma with low fat content

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.

Identification of a specific ultrasonographic finding for differentiating hepatic angiomyolipoma from hepatocellular carcinoma

OBJECTIVE

To identify specific ultrasonographic features that differentiate hepatic angiomyolipoma (HAML) from hepatocellular carcinoma (HCC).

METHODS

Twelve patients with HAML and 73 patients with HCC, whose diagnosis were pathologically confirmed at a single center in Japan between 2006 and 2016, were included in this study. The HAML and HCC cases were histologically evaluated and their histological growth patterns were compared. Using ultrasonographic data, we evaluated the imaging features representing the distinct histological differences. Ultrasonographic findings, reviewed by two examiners, were compared via interobserver variability analysis. This retrospective study was approved by the institutional ethics committee at our institute (No. 2017-1004).

RESULTS

The enrolled patients were carefully divided into two case sets: discovery case set (6 HAML patients and 37 HCC patients) and validation case set (6 HAML patients and 36 HCC patients). In the discovery case set, half of the HAML cases had intratumoral regions showing a reticular growth pattern. None of the HCC cases appeared as a region with the reticular growth pattern. The regions with the reticular growth pattern present as an intratumoral hyper echoic foci on ultrasound images. The presence of the intratumoral hyper echoic foci was significantly associated with HAML (P < .01). In the validation case set, the intratumoral hyper echoic foci predicted HAML at a specificity of 100% and a sensitivity of 50%.

CONCLUSIONS

Intratumoral hyper echoic foci, representing reticular growth pattern, can be a promising ultrasonographic finding to help differentiate HAML from HCC.

Hepatic angiomyolipoma: differential diagnosis from other liver tumors in a special reference to vascular imaging - importance of early drainage vein

A 51-year-old female had been diagnosed with a hemangioma in the hepatic segment 6 (S6). After a 6-year follow-up, enlargement of the tumor was detected. The tumor was clearly enhanced in the arterial phase, and the enhancement remained in the portal phase on computed tomography (CT). Although the primary differential diagnosis on CT was hepatocellular carcinoma (HCC), we worried about the possibility of other vessel system tumors because the tumor remained to be enhanced at the portal phase for HCC and all tumor markers of HCC were negative. We performed angiography to determine the tumor nature and to seek other tumors. Angiography showed tumor stain at the hepatic S6 with an early obvious drainage vein from the tumor flowing through the right hepatic vein into the inferior vena cava. In addition to tumor stain and the drainage vein, there were many small poolings of contrast medium in the whole liver, which were suspected as dilatation of the hepatic peripheral artery. We suspected the tumor as a benign tumor such as hepatocellular adenoma or focal nodular hyperplasia, but the possibility of HCC could not be ruled out. Hepatic posterior sectionectomy was done to completely remove the drainage vein with the tumor. Intraoperative histological examination revealed the tumor as not malignant and not HCC. Later, immunohistochemical analysis uncovered that the tumor had high expression of HMB-45 and, therefore, the final diagnosis was angiomyolipoma. We think that detecting an early drainage vein from the tumor would be a key point for diagnosing hepatic angiomyolipoma.

Real-time contrast-enhanced ultrasonography of resected and immunohistochemically proven hepatic angiomyolipomas

PURPOSE

The purpose of this study was to assess real-time contrast-enhanced ultrasound in patients with hepatic angiomyolipomas with respect to contrast-enhancing kinetics and enhancement patterns.

MATERIALS AND METHODS

Nonlinear, low mechanical index (mechanical index less than 0.2), real-time contrast-enhanced ultrasonography was performed in 18 patients with 19 tumors after 2.4 mL bolus injection of contrast agent SonoVue. All the 19 tumors were surgically resected and immunohistochemically proven sporadic hepatic angiomyolipomas.

RESULTS

Inhomogeneous hyperenhancing pattern was detected 16 tumors (84.2%) and homogeneous hyperenhancing pattern in 1 tumor (0.5%) in arterial phase and portal phase, 16 lesions remained hyperenhancement but one lesion became isoenhancement in late phase. Two lesions (10.5%) were detected inhomogeneously hypoenhancement compared to liver parenchyma during arterial, portal, and late phases, with only punctiform internal enhancement. The margin of all the lesions were smooth and well defined on contrast-enhanced ultrasonography, whereas no peripheral nodular arterial enhancement, centripetal filling, or spoke-wheel like enhancement pattern were depicted. Early strong enhancement in arterial phase, rapid washout of contrast agent, and appear hypoechoic to surrounding liver tissue during portal or late phase was not at all observed.

CONCLUSION

Real-time contrast-enhanced ultrasonography can demonstrate typical imaging characteristics of hepatic angiomyolipomas in most cases, that is, inhomogeneous hyperenhancing pattern in arterial phase, prolonged hyperenhancement during portal and late phase with smooth and well-defined margin. This real-time dynamic imaging technique may therefore improve noninvasive characterization and differentiation of this rare, benign, hepatic mesenchymal neoplasm.

Unusual sonographic appearance of a huge angiomyolipoma of the liver

Hepatic angiomyolipoma is a rare, benign, hepatic mesenchymal neoplasm. We report a case of an extremely large hepatic angiomyolipoma in a 58-year-old woman with unusual sonographic features. The tumor was well demarcated from the surrounding liver and showed a heterogeneous cystic appearance with a thick echogenic rim. Color Doppler showed blood flow in the echogenic rim and around the lesion. Contrast sonography demonstrated strong enhancement in the solid rim from early arterial phase to the late phase and no enhancement in the central cystic part of the lesion. Spiral CT showed a well-defined huge heterogeneous cystic mass with fatty density. At surgery the tumor was soft and encapsulated with a thin, smooth membrane. The cut surface of the tumor revealed a cystic appearance with necrotic tissue. The diagnosis of hepatic angiomyolipoma was confirmed by immunohistochemistry.

Imaging features of hepatic angiomyolipomas on real-time contrast-enhanced ultrasound

The aim of this study was to evaluate the imaging features of hepatic angiomyolipoma (AML) on contrast-enhanced ultrasound (CEUS). The imaging features of 12 pathologically proven hepatic AML lesions in 10 patients who had undergone baseline ultrasound (BUS) and CEUS examinations were evaluated retrospectively. The enhancement extent, pattern and dynamic change, along with the enhancement process, on CEUS were analysed. The diagnostic results of BUS and CEUS before pathological examination were also recorded. The results showed that 75% (9/12) of the AML lesions exhibited mixed echogenicity on BUS and most showed remarkable hyperechogenicity in combination with a hypoechoic or anechoic portion. Arterial flow signals were detected in 75% (9/12) of the lesions on colour Doppler imaging. On CEUS, 66.7% (n = 8) of the 12 lesions exhibited hyperenhancement in the arterial phase, slight hyperenhancement (n = 2) or isoenhancement (n = 6) in the portal phase, and slight hyperenhancement (n = 1) or isoenhancement (n = 7) in the late phase. Three (25%) lesions exhibited hyperenhancement in the arterial phase and hypoenhancement in both portal and late phases. One (8.3%) lesion exhibited hypoenhancement throughout the CEUS process. Before pathological examination with BUS, only 3 (25%) lesions were correctly diagnosed as hepatic AML. Conversely, on CEUS, correct diagnoses were made for 66.8% (8/12) of hepatic AMLs. Therefore, arterial hyperenhancement and subsequent sustained enhancement on CEUS were found in the majority of hepatic AMLs. The combination of BUS and CEUS leads to the correct diagnosis in the majority of hepatic AMLs, and is higher than the success rate achieved by BUS alone.

Hepatic angiomyolipoma: identification of an efferent vessel as a hepatic vein by contrast-enhanced harmonic sonography

Two cases of hepatic angiomyolipoma were studied by contrast-enhanced harmonic sonography. The special tumor hemodynamics, namely the efferent blood flow of the hepatic angiomyolipoma draining into the hepatic vein, were clearly shown on harmonic imaging, and they corresponded well with those seen on angiography and computed tomography during angiography. Benign hepatic tumors were diagnosed preoperatively in both cases according to the hemodynamic findings. Hepatic angiomyolipoma was finally identified histologically. The special tumor hemodynamics might be one of the important characteristics of hepatic angiomyolipoma. Contrast-enhanced harmonic sonography is useful for the detection of special tumor hemodynamics and may facilitate the differential diagnosis from other hepatic tumors, especially malignant liver tumors.

Hepatic angiomyolipoma: identification of an efferent vessel to be hepatic vein by contrast-enhanced harmonic ultrasound

We report two patients with rare hepatic angiomyolipoma and demonstrate the special tumour haemodynamics with contrast-enhanced harmonic ultrasound. This reliably identified the efferent vessel of the hepatic angiomyolipoma to be the hepatic vein in both cases, which corresponded well with that seen on conventional angiography and CT angiography. This haemodynamic finding may be an important characteristic of hepatic angiomyolipoma, and facilitate the differential diagnosis from other benign and malignant hepatic tumours.

Hepatic angiomyolipoma: demonstration by out of phase MRI

Hepatic angiomyolipoma is a rare liver pathology. In this case report, we describe MRI features of a hepatic angiomyolipoma with a high fat content, which was indeterminate on CT. In phase and out of phase T1-weighted spoiled gradient echo technique, T2-weighted fat suppressed fast spin echo technique and dynamic enhanced T1-weighted in phase gradient echo technique were used. Out of phase gradient echo sequence was the most sensitive technique identifying the fat content of the lesion in its mixed tissue composition.

Benign liver neoplasms

A variety of benign focal liver lesions are easily characterized with currently available imaging techniques and contrast agents. The most common benign liver lesions, such as hemangioma, bile duct cyst, and FNH, reveal characteristic cross-sectional imaging features that allow an accurate diagnosis. For atypical variants and more uncommon lesions, including HCA, angiomyelioma, infantile hemagioendothelioma, and mesenchymal hamartoma, integration of clinical data can often help in the interpretation of imaging studies. Finally, for the remaining lesions, such as hepatic adenomatosis, the imaging findings may not be specific enough to negate the need for a tissue biopsy.