Hemodynamic characterization of hepatic angiomyolipoma with least amount of fat evaluated by contrast-enhanced magnetic resonance angiography

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Clinicopathological correlation and post-resection outcomes of hepatic angiomyolipoma

Backgrounds/Aims

Angiomyolipoma is a rare neoplasm of mesenchymal origin derived from perivascular epithelioid cells. Due to rarity, hepatic angiomyolipoma (HAML) has been often misdiagnosed as hepatocellular carcinoma (HCC) or other hypervascular liver tumors based on imaging studies. This study investigated the clinicopathological correlation and post-resection outcomes of HAML.

Methods

This retrospective observational study included 40 patients who underwent hepatic resection (HR) for HAML between 2008 and 2018.

Results

Mean age of the patients was 42.6±11.4 years and there were 30 (75.0%) females. Hepatitis B and C virus infection was present in 8 patients (20.0%) and 1 patient (2.5%), respectively. Preoperative diagnoses on imaging studies were HCC in 23 (57.5%) patients, HAML in 14 (35.0%) patients, focal nodular hyperplasia in 2 (5.0%) patients, and hepatic adenoma in 1 (2.5%) patient. Percutaneous liver biopsy was performed in 10 (25.0%) patients and HAML was diagnosed in all patients. Only 3 patients (7.5%) showed a slight elevation in the level of liver tumor markers. Major HR was performed in 10 (25.0%). Laparoscopic HR was performed in 9 (22.5%). The mean tumor size was 4.8±3.9 cm and single tumor was present in 38 (95.0%) patients. Currently, all the patients are alive without tumor recurrence during the follow-up observation period of 75.7±37.3 months.

Conclusions

HAML is a rare form of primary liver tumor and is often misdiagnosed as HCC or other hypervascular tumors. Although HAML is benign in nature, it has malignant potential, thus resection is indicated if the tumor grows or malignancy cannot be excluded.

Differentiating Hepatic Epithelioid Angiomyolipoma From Hepatocellular Carcinoma and Focal Nodular Hyperplasia via Radiomics Models

Background: We conduct a study in developing and validating two radiomics-based models to preoperatively distinguish hepatic epithelioid angiomyolipoma (HEAML) from hepatic carcinoma (HCC) as well as focal nodular hyperplasia (FNH).

Methods: Totally, preoperative contrast-enhanced computed tomography (CT) data of 170 patients and preoperative contrast-enhanced magnetic resonance imaging (MRI) data of 137 patients were enrolled in this study. Quantitative texture features and wavelet features were extracted from the regions of interest (ROIs) of each patient imaging data. Then two radiomics signatures were constructed based on CT and MRI radiomics features, respectively, using the random forest (RF) algorithm. By integrating radiomics signatures with clinical characteristics, two radiomics-based fusion models were established through multivariate linear regression and 10-fold cross-validation. Finally, two diagnostic nomograms were built to facilitate the clinical application of the fusion models.

Results: The radiomics signatures based on the RF algorithm achieved the optimal predictive performance in both CT and MRI data. The area under the receiver operating characteristic curves (AUCs) reached 0.996, 0.879, 0.999, and 0.925 for the training as well as test cohort from CT and MRI data, respectively. Then, two fusion models simultaneously integrated clinical characteristics achieved average AUCs of 0.966 (CT data) and 0.971 (MRI data) with 10-fold cross-validation. Through decision curve analysis, the fusion models were proved to be excellent models to distinguish HEAML from HCC and FNH in comparison between the clinical models and radiomics signatures.

Conclusions: Two radiomics-based models derived from CT and MRI images, respectively, performed well in distinguishing HEAML from HCC and FNH and might be potential diagnostic tools to formulate individualized treatment strategies.

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.

Comparison of MRI Features of Epithelioid Hepatic Angiomyolipoma and Hepatocellular Carcinoma: Imaging Data From Two Centers

Introduction: Epithelioid hepatic angiomyolipoma (Epi-HAML) can easily be misdiagnosed as a malignant tumor such as hepatocellular carcinoma (HCC) because of the low-fat content on imaging. We analyzed and compared the magnetic resonance imaging (MRI) features of Epi-HAML and HCC, which would aid in disease diagnosis.

Methods: We included 30 pathologically confirmed patients with Epi-HAML and 80 with HCC, who underwent both MRI unenhanced scan and three-phase contrast-enhanced MRI scan. The clinical and MRI features of the two groups were summarized and analyzed.

Results: Epi-HAML showed significant differences compared to HCC group in terms of clinical features such as sex preference, age, concomitant diseases (hepatitis B and cirrhosis), and elevated plasma alpha-fetoprotein (AFP) (P < 0.001). In addition, there were statistically significant differences between both tumor types with regard to conventional MRI findings such as a solitary tumor (100 vs. 83.8%, P = 0.018), well-defined (93.3 vs. 71.3%, P = 0.027), mild hyperintensity (40.0 vs. 3.7%, P < 0.001) on DWI with high b-value, fat within the tumor (43.3 vs. 8.8%, P < 0.001), and rare necrosis (3.3 vs. 26.3%, P = 0.016). Besides, Epi-HAML displayed significant differences compared to HCC in terms of contrast-enhanced MRI characteristics such as draining hepatic vein (30.0 vs. 3.8%, P < 0.001), portal vein tumor thrombus (0 vs. 13.8%, P = 0.033), hypointensity at delayed phase (70.0 vs. 95%, P = 0.001), intra-tumor vessel at delayed phase (36.7 vs. 10.0%, P = 0.003), pseudocapsule (20.0 vs. 78.8%, P < 0.001), and prolonged enhancement (56.7 vs. 1.2%, P < 0.001).

Conclusion: Epi-HAML frequently occurs in middle-aged women and usually lacks characteristic clinical symptoms. Typically, Epi-HAML presents as an isolated and well-defined tumor with rich vasculature. Specific MRI features such as intra-tumor fat, intra-tumor vessel, draining hepatic vein, prolonged enhancement, and lack of capsule may contribute to a more confident diagnosis of Epi-HAML.

Hepatic epithelioid angiomyolipoma with renal metastasis: radiologic-pathologic correlation

Epithelioid angiomyolipoma (EAML) is a rare subtype of angiomyolipomas. Unlike the conventional angiomyolipomas, EAML often contains minimal fat which usually precludes prospective diagnosis on imaging. The imaging findings of EAML may overlap with other benign and malignant hepatic neoplasms. We report a hepatic epithelioid angiomyolipoma in a 47-year-old female which metastasized to the right kidney and recurred after resection in the liver. We analyze the imaging findings of EAML on ultrasound, computed tomography, positron emission tomography and magnetic resonance imaging. Correlation between the imaging and histopathologic findings is made. The estimated annual growth and doubling time of the primary hepatic EAML are calculated. To the best of our knowledge, this is the first published report of positron emission tomography–computed tomography findings and annual growth rate for hepatic EAML.

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.

Clinico-pathological correlation of hepatic angiomyolipoma: a series of 23 resection cases

BACKGROUND

Angiomyolipomas are rare neoplasms of mesenchymal origin and are derived from perivascular epithelioid cells. They usually develop in the kidney and rarely in the liver. Due to their rarity, most hepatic angiomyolipomas have been misinterpreted as hepatocellular carcinoma (HCC) or other hypervascular liver tumours on imaging studies. We aimed to assess the clinico-pathological correlation of hepatic angiomyolipoma.

METHODS

We identified 23 patients with hepatic angiomyolipoma through an institutional database search.

RESULTS

Of 5680 cases of primary liver tumours, 23 (0.4%) had angiomyolipomas (mean age, 43.6 ± 12.4 years; 16 female patients). Hepatitis B virus infection was noted in four patients, whereas a liver mass was incidentally detected on routine health screening in 13 patients. The preoperative diagnoses, before liver biopsy, included HCC in 14, angiomyolipoma in six, focal nodular hyperplasia in two and hepatic adenoma in one patient. Eventually, the preoperative diagnoses were changed to HCC in 12 and hepatic angiomyolipoma in 11 patients. The tumour size was 5.3 ± 4.6 cm, and 22 patients had a single tumour. All tumours exhibited positive findings for human melanoma black-45 and smooth muscle actin staining. During a follow-up period of 52.2 ± 23.7 months, none of the patients exhibited tumour recurrence or mortality.

CONCLUSIONS

Hepatic angiomyolipoma is a rare form of primary liver tumour and is often misdiagnosed as other hypervascular tumours. Although angiomyolipoma is benign in nature, it also has malignant potential; hence, resection is indicated if the tumour grows or malignancy cannot be excluded. Surgical resection is a definitive curative treatment of hepatic angiomyolipoma.

Hepatic epithelioid angiomyolipoma is a rare and potentially severe but treatable tumor: A report of three cases and review of the literature

Hepatic epithelioid angiomyolipoma (EAML) is a rare type of hepatic tumor. Due to a lack of adequate understanding about this tumor, hepatic EAML is often misdiagnosed as other diseases with similar clinical characteristics such as hepatic cancer. In the present study, 3 cases of hepatic EAML are reported, and the main clinicopathological features of this disease are presented, based on a literature search that included articles published in English between February 2000 and September 2014. A total of 24 hepatic EAML cases were considered, of which, 17 were females and 4 presented multiple liver lesions. Among the patients with single lesions, 2 underwent surgery and relapsed after 5 months and 9 years, respectively. Immunohistochemical staining was positive for human melanoma black-45 in the present 3 cases. The aim of the present study was to focus the attention of clinicians on this type of hepatic tumor in order to improve its diagnosis and treatment.

Comparison of CT and contrast-enhanced ultrasound findings in hepatic angiomyolipoma with pathological correlations

OBJECTIVE

To compare imaging findings of CT and contrast-enhanced US (CEUS) in hepatic angiomyolipoma (HAML) and investigate their pathological correlations.

METHODS

Imaging findings and preoperative diagnosis of CT and CEUS were retrospectively compared head to head in 46 patients with 54 histologically proven HAMLs. Correlations between imaging features and preoperative diagnosis with pathological types of HAMLs were analyzed.

RESULTS

Fat was detected in 100% of lipomatous type, 84.6% of mixed type, and 7.1% of myomatous type (p = 0.000) of HAML at unenhanced CT. Well-defined hyper-echogenicity was displayed in 100% of lipomatous type, 88.5% of mixed type, 50% of myomatous type, and 66.7% of angiomatous type of HAMLs at unenhanced US. More arterial hyper-enhancement was noted on CEUS (100%) than on CT (73.1%) in mixed type (p = 0.015) and in lipomatous type (90.9% vs. 9.1%, p = 0.000) of HAMLs. Washout was present in more HAMLs on CT than on CEUS (42.6% vs. 18.5%, p = 0.007). Correct preoperative diagnosis was suggested in more HAMLs of myomatous type on CEUS than on CT (42.9% vs. 0%, p = 0.016) but showed no difference in other types of HAMLs.

CONCLUSION

There are considerable discrepancies between CT and CEUS findings of HAMLs, and the imaging appearance and preoperative diagnosis of HAMLs on CT and CEUS are significantly affected by pathological types of HAMLs.

Myomatous hepatic angiomyolipoma: imaging findings in 14 cases with radiological-pathological correlation and review of the literature

OBJECTIVE

To display and analyse the imaging features of myomatous hepatic angiomyolipomas (MHAMLs).

METHODS

The imaging features (CT = 9; MRI = 10; ultrasound = 10; contrast-enhanced ultrasound = 4) of 14 patients with pathologically proven MHAMLs were reviewed retrospectively.

RESULTS

MHAMLs were surgically resected in the 14 patients (10 females and 4 males; age, 27-64 years; mean, 45 years), all of whom had negative hepatitis markers and were positive for the immunohistochemical stain homatropine methylbromide-45. The tumours were solitary and well defined, and ranged in size from 1.9 to 9.1 cm (mean, 5.7 cm). On dynamic contrast-enhanced CT, MRI and ultrasound scans, all tumours showed fast strong enhancement in the arterial phase and moderate washout in the portal venous and delayed phases, and the greater portions of the tumours were slightly lower than the surrounding hepatic parenchyma. In some cases, a small area of prolonged or increasing enhancement in the tumour was recognized in the delayed phase. Early draining vessels to the portal vein or hepatic vein could be seen in some cases. However, no capsular signs could be confidently identified in the delayed phase. Haemorrhagic cavities were recognized in two cases, and nodular low-intensity areas in the tumours on T2 weighted imaging that showed slow and faint enhancement on dynamic scans were seen in two cases. However, no necrosis was identified.

CONCLUSION

Dynamic enhanced imaging studies revealed some specific features of MHAMLs that distinguish them from other hypervascular hepatic tumours, especially when combined with clinical features. Familiarity with imaging and clinical features of MHAMLs could avoid unnecessary surgical resection of these generally benign tumours.

ADVANCES IN KNOWLEDGE

This article systematically describes the imaging features of MHAMLs.

Epithelioid angiomyolipoma of the liver: CT and MRI features

The purpose of our study was to retrospectively evaluate the computed tomography (CT)/magnetic resonance imaging features of epithelioid angiomyolipoma of the liver (Epi-HAML), with pathology as a reference. We reviewed the CT/MRI findings of six lesions of Epi-HAML and found absence of adipose tissue in the lesions. In addition, recognizing the imaging features of no capsule, and hypervasularity with central punctiform or filiform vessels as a characteristic enhancement may distinguish Epi-HAML from other hepatic tumors.

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.

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.

Three cases of angiomyolipoma: diagnostic imaging by contrast-enhanced ultrasonography

We used contrast-enhanced ultrasound using the Sonazoid microbubble contrast agent to diagnose three cases of hepatic angiomyolipoma, which is a rare benign tumor. Some characteristic findings are obtained in the early vascular phase, for example fork-like tumor vessels. However, a variety of findings are seen after the early vascular phase because of microbubbles circulating the vascular enriched tumor.