Epithelioid angiomyolipoma of the liver: Cross-sectional imaging findings of 10 immunohistochemically-verified cases

Hepatic perivascular epithelioid cell tumors: The importance of preoperative diagnosis

Accurate preoperative diagnosis is highly important for the treatment of perivascular epithelioid cell tumors (PEComas) because PEComas are mainly benign tumors and may not require surgical intervention. By analyzing the causes, properties and clinical manifestations of PEComas, we summarize the challenges and solutions in the diagnosis of PEComas.

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.

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.

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.

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.

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.

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 hepatic epithelioid angiomyolipoma and non-hepatitis B, non-hepatitis C hepatocellular carcinoma on contrast-enhanced ultrasound

PURPOSE

The purpose of this study was to retrospectively compare the imaging features of hepatic epithelioid angiomyolipoma (HEAML) to those of hepatocellular carcinoma negative for hepatitis B surface antigen and hepatitis C antibody (NBNC-HCC) on contrast-enhanced ultrasound (CEUS) with sulphur hexafluoride microbubbles.

MATERIAL AND METHODS

Twenty-two patients (4 men, 18 women) with a mean age of 42.6±10.2 (SD) years (range: 22-63 years) with histopathologically confirmed HEMAL were included in the study. Forty-four patients (30 men, 14 women) with a mean age of 57.3±15.9 years (range: 19-85 years) with histopathologically confirmed NBNC-HCC were randomly selected from our institution's database as a control group. The CEUS characteristics of the two groups were compared.

RESULTS

On conventional ultrasound, significant differences in tumor diameter were found between HEAML (4.0±2.0 [SD] cm; range: 1.3-8.9cm) and NBNC-HCC (8.4±4.4 [SD] cm; range: 1.6-18cm) (P<0.001) as well as in degrees of enhancement during the portal (P=0.001) and late phases (P=0.003), contrast distribution (P<0.001) and absence of pseudocaspule (P<0.001). On CEUS, hyperenhancement during the arterial phase was observed in 21/22 (95.5%) HEAMLs and in 43/44 (97.7%) NBNC-HCCs (P>0.999). Homogeneous enhancement was more frequent in HEAMLs (20/22; 90.9%) than in NBNC-HCCs (13/44; 29.6%) (P<0.001). Pseudocapsule was observed in 0/22 HEAMLs (0.0%) and in 36/44 NBNC-HCCs (81.8%) (P=0.017). A prolonged enhancement was observed in 5/22 HEAMLs (22.7%) and in 0/44 NBNC-HCCs (0.0%) (P<0.001) during the late phase.

CONCLUSION

CEUS with sulphur hexafluoride microbubbles is helpful in discriminating between HEAML and NBNC-HCC. Homogeneous enhancement and lack of pseudocapsule are suggestive features for the diagnosis of HEAML.

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.

Challenging liver lesions in noncirrhotic patients: Report of three cases

We describe three cases of liver lesions, characterized by a discrepancy between presurgical imaging and histological features, in which the final histological diagnosis was quite different from what the surgeons expected. We present (1) a case of primary liver angiomyolipoma associated with focal nodular hyperplasia, (2) a case of perivascular epithelioid cell tumor, and (3) a case of liver splenosis associated with focal nodular hyperplasia. In all cases, a presurgical diagnosis of hepatocellular adenoma was made. Due to nonspecific clinical and radiological features, these rare liver lesions are often presurgically misdiagnosed, especially in young noncirrhotic patients. The association among different lesions represents one additional diagnostic challenge.

Two case reports and literature review for hepatic epithelioid angiomyolipoma: Pitfall of misdiagnosis

BACKGROUND

Hepatic epithelioid angiomyolipoma (HEAML) is a rare liver disease and is easily misdiagnosed. Enhanced recognition of HEAML is beneficial to the differential diagnosis of rare liver diseases.

CASE SUMMARY

We presented two cases of HEAML in Changzheng Hospital, Naval Medical University, and then collected and analyzed all reports about HEAML recorded in PubMed, MEDLINE, China Science Periodical Database, and VIP database from January 2000 to March 2018. A total of 409 cases of HEAML in 97 reports were collected, with a ratio of men to women of 1:4.84 and an age range from 12 years to 80 years (median 44 years). Among the patients with clinical symptoms mentioned, 61.93% (205/331) were asymptomatic, 34.74% (115/331) showed upper or right upper quadrant abdomen discomfort, while a few of them showed abdominal mass, gastrointestinal symptoms, low fever, or weight loss. The misdiagnosis rate of HEAML was as high as 40.34% (165/409) due to its nonspecific imaging findings. Most of the tumors were solitary and round in morphology, with clear boundaries. Ultrasound scan indicated low echo with internal nonuniformity and rich blood supply in most cases. Computer tomography/magnetic resonance imaging enhanced scan showed varied characteristics. The ratio of fast wash-in and fast wash-out, fast wash-in and slow wash-out, and delayed enhancement was roughly 4:5:1. A definite diagnosis of HEAML depended on the pathological findings of the epithelioid cells in lesions and the expression of human melanoma black 45, smooth muscle actin, melanoma antigen, and actin by immunohistochemical staining. HEAML had a relatively low malignant rate of 3.91%. However, surgical resection was the main treatment for HEAML, due to the difficulty diagnosing before operation.

CONCLUSION

HEAML is a rare and easily misdiagnosed disease, and it should be diagnosed carefully, taking into account clinical course, imaging, pathological ,and immunohistochemical findings.

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.

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.

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: clinical features and imaging findings of contrast-enhanced ultrasound and CT

AIM

To evaluate the clinical features and imaging findings of epithelioid angiomyolipoma (EAML) on contrast-enhanced ultrasound (CEUS) and contrast-enhanced computed tomography (CECT).

MATERIALS AND METHODS

During January 2006 to November 2015, six patients with histopathologically proven hepatic EAML were evaluated using both CECT and ultrasonography. Six patients underwent CEUS and four patients had CECT images. Patients' demographics, clinical presentations, laboratory test results, and imaging appearances were collected and analysed.

RESULTS

Six patients were female, and the mean age was 43.5 years. All hepatic EAMLs were solitary. None of patients had specific symptoms, and laboratory tests were normal in all patients. The maximal diameter of the lesions ranged from 3.1 to 6.5 cm (mean 4.4 cm). Baseline ultrasound revealed that 50% of hepatic EAMLs were hypo-echoic and 50% were mixed echoic. CEUS showed that 100% of the hepatic EAMLs displayed homogeneous hyperenhancement in the arterial phase and 67% (4/6) showed hypo-enhancement in the late phase. On CECT, 100% (4/4) of the neoplasms were significantly hyperenhanced in the arterial phase and washout in the portal phase. There was no recurrence or metastasis after a mean follow-up period of 11.8 months.

CONCLUSION

Hepatic EAML shows similar enhancement patterns to that of hepatocellular carcinoma. It should be considered as a possible differential diagnosis in female patients without viral hepatitis infection.

Primary hepatic epithelioid angiomyolipoma: A malignant potential tumor which should be recognized

AIM: To improve the clinical diagnosis and recognition of hepatic epithelioid angiomyolipoma (HEAML).

METHODS: Four cases of primary HEAML were confirmed based on the pathology archive system in our hospital from January 2009 to November 2015. The general state, clinical symptoms, imaging manifestations, histological results and immunohistochemistry of these patients were retrospectively reviewed and analyzed. Studies of HEAML published in the last 15 years were collected from PubMed and MEDLINE to summarize the clinical symptoms, imaging characteristics, pathological features and management of HEAML.

RESULTS: Four cases of primary HEAML were retrieved from our archives. These included three female patients and one male patient, with a mean age of 41.8 ± 11.5 years (ranging from 31 to 56 years). The mean tumor size was 7.3 ± 5.5 cm (ranging from 3.0 to 15 cm). In the contrast-enhanced imaging, the tumor was obviously enhanced in the arterial phase, but enhanced continuously or exhibited a slow-density masse during the venous and delayed phases. Histologically, the tumors mainly consisted of epithelioid cells that comprised approximately 95% of the total neoplastic mass. Although no metastases occurred in our patients, pathological studies revealed necrosis, mitotic figures and liver invasion in two patients, which indicates aggressive behavior. Immunohistochemical staining revealed that human melanoma black 45 (HMB-45) and Melan-A were positive in 4 cases. We only identified 81 cases with primary HEAML, including our present patients, from 26 articles available from PubMed and MEDLINE. The majority of the papers were published as case reports. Only 5 (5/75, 6%) cases were associated with tuberous sclerosis complex (TSC). More than half (35/66) were discovered incidentally upon physical examination. Approximately 65% (22/34) of the patients were misdiagnosed with HCC or other tumors before surgery. Approximately 10% (8/81) of the patients with HEAML had recurrence or metastasis after surgery, which was a very high and alarming rate.

CONCLUSION: HEAML is a very rare primary hepatic tumor that is often misdiagnosed before surgery. Patients should be followed closely after surgery because of its malignant potential.

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.

Differentiation of hepatocellular carcinoma from its various mimickers in liver magnetic resonance imaging: What are the tips when using hepatocyte-specific agents?

Hepatocellular carcinoma is the most common primary hepatic malignant tumor. With widespread use of liver imaging, various cirrhosis-related nodules are frequently detected in patients with chronic liver disease, while diverse hypervascular hepatic lesions are incidentally detected but undiagnosed on dynamic computed tomography and magnetic resonance imaging (MRI). However, use of hepatocyte-specific MR contrast agents with combined perfusion and hepatocyte-selective properties have improved diagnostic performance in detection and characterization of focal liver lesions. Meanwhile, the enhancement patterns observed during dynamic phases using hepatocyte-specific agents may be different from those observed during MRI using conventional extracellular fluid agents, leading to confusion in diagnosis. Therefore, we discuss useful tips for the differentiation of hepatocellular carcinoma from similar lesions in patients with and without chronic liver disease using liver MRI with hepatocyte-specific agents.

Differentiation of lipid poor angiomyolipoma from hepatocellular carcinoma on gadoxetic acid-enhanced liver MR imaging

PURPOSE

To investigate magnetic resonance (MR) findings of angiomyolipoma (AML) on gadoxetic acid-enhanced MR imaging, and to identify features that differentiate AML from hepatocellular carcinoma (HCC) in patients with a low risk of HCC development.

METHODS

This retrospective study was institutional review board approved, and the requirement for informed consent was waived. Twelve patients with hepatic AML who underwent gadoxetic acid-enhanced MRI with no risk factors for HCC development were recruited. Twenty-seven patients with HCC under the same inclusion criteria were recruited as control. Two radiologists analyzed the images in consensus for morphologic features, enhancement patterns, and hepatobiliary phase (HBP) findings. All results were analyzed using the Mann-Whitney test, two-tailed Fisher exact test, and chi-square test.

RESULTS

Patients with AML were younger than those with HCC (48.8 ± 15 years for AML vs. 62.7 ± 14.2 years for HCC, p = 0.008) with female predominance, while most HCC patients were male (75% (9/12) vs. 15% (4/27), p < 0.001). The most prevalent enhancement pattern was arterial enhancement followed by hypointensity at portal or transitional phases for both AMLs (58% (7/12)) and HCCs (74% (20/27)) (p = 0.455). However, during the HBP, AMLs frequently showed more homogeneous hypointensity than HCCs (83% (10/12) vs. 41% (11/27), p = 0.018). When compared with the signal intensity of the spleen, the mean relative signal intensity of the AML was 91.2 ± 15.4%, while in HCCs, it was 128.7 ± 40% (p < 0.001).

CONCLUSIONS

Although AMLs showed similar enhancement patterns to HCCs during the dynamic phases of gadoxetic acid-enhanced MRI, using characteristic MR features of AML during the HBP and demographic differences, one can better differentiate AML from HCC.

Visualizing Central Vessels of Hepatic Angiomyolipoma Devoid of Fat Using a 2D Multi-Breath-Hold Susceptibility-Weighted Imaging

Epithelioid hepatic angiomyolipoma (Epi-HAML) is a rare benign mesenchymal tumor with malignant potential. Most of Epi-HAML contains no or only a minimal amount of adipose tissue and poses a diagnostic challenge. Central vessels are characteristic imaging finding of Epi-HAML, which usually were displayed by dynamic contrast imaging. In this paper, we displayed the central vessels of Epi-HAML invisible on conventional MR images using a new developed abdominal susceptibility-weighted imaging (SWI). To the best of our knowledge, this is the first description for the role of SWI in characterization of Epi-HAML.

Gd-EOB-DTPA-enhanced and diffusion-weighted magnetic resonance findings in hepatic epithelioid angiomyolipoma: A case report

The present study reports a case of histologically proven hepatic epithelioid angiomyolipoma that was evaluated with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging and diffusion-weighted imaging. A 23-year-old female was admitted to the Northern Jiangsu People's Hospital (Yangzhou, Jiangsu, China) due to a 5.6-cm mass in the liver, and a right partial hepatectomy was performed. Magnetic resonance imaging (MRI) revealed a hypointense mass on T1-weighted imaging, and a hyperintense mass on T2-weighted and diffusion-weighted imaging, with a higher apparent diffusion coefficient value compared with normal liver parenchyma. On the dynamic Gd-EOB-DTPA-enhanced MRI scan, the lesion manifested as hypervascular with multiple filiform vessels and a pseudocapsule image, and in the hepatobiliary phase the lesion demonstrated a lack of contrast retention, thus appearing hypointense compared with the background liver. Pre-operatively, EMAL was diagnosed on the basis of these findings in the tumor. The optimum treatment is complete surgical excision and subsequent follow-up. The patient was healthy and free from recurrence at 6 months and 1 year post-surgery. Therefore, knowledge of EAML specific features on dynamic Gd-EOB-DTPA-enhanced and DWI scans may improve the diagnostic accuracy of hypervascular hepatic tumors and may facilitate treatment selection.

Hepatic epithelioid angiomyolipoma with arterioportal venous shunting mimicking hepatocellular carcinoma: report of a case

A patient with hepatic epithelioid angiomyolipoma (Epi-AML) with arterioportal venous shunting, who was successfully treated by a laparoscopic left lateral sectionectomy, is presented herein. AML is an uncommon benign neoplasm of the liver. Tumors composed predominantly of epithelioid cells have been subcategorized into Epi-AML, and the treatment strategy for Epi-AML is currently undetermined. There are no reports describing Epi-AML with arterioportal venous shunting to date. An arterioportal venous shunting of the liver tumor was suggested to be one of the malignant signs of the liver tumor. It would be important to differentiate Epi-AML with arterioportal venous shunting from hepatocellular carcinoma and hypervascular metastatic tumors. Minimally invasive resection, such as laparoscopic hepatectomy, for patients having Epi-AML with arterioportal venous shunting may be recommended.

MRI manifestations of liver epithelioid and nonepithelioid angiomyolipoma

PURPOSE

To retrospectively analyze the magnetic resonance imaging (MRI) manifestations of liver AML and compare the MRI manifestations of epithelioid and nonepithelioid angiomyolipoma (AML).

MATERIALS AND METHODS

The study comprised a retrospective analysis of 11 patients whose hepatic AML was confirmed by surgical pathology. Routine MRI examination was performed in 11 patients, of which five were cases of epithelioid AML and six were cases of nonepithelioid AML. One case of nonepithelioid AML underwent a plain MRI scan only, while the remaining 10 patients underwent MRI and dynamic contrast-enhanced scans.

RESULTS

Chemical shift imaging detected more fat component cases than frequency the saturation method did (7/11 vs. 3/11). The difference was not statistically significant, however (P = 0.236). The degree of fatty component was different between epithelioid and nonepithelioid AML, but there was no significant difference between them (P = 0.766). Of the 10 cases in which enhancement scans were performed, nine had hyperenhancement in the arterial phase, and nine had capsule enhancement on delayed phase.

CONCLUSION

The amount of fat content is not related to whether the tumor is epithelioid or nonepithelioid. Under dynamic contrast-enhancement MRI, epithelioid AML shows enhancement patterns similar to those of classic AML rich in vascular smooth muscles.

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.

Epithelioid angiomyolipoma of the liver: a clinicopathologic study of 5 cases

This study aimed to study the clinicopathologic characteristics of epithelioid angiomyolipoma, a variant of angiomyolipoma (AML) in the liver; and to discuss the diagnostic challenges. Five cases of primary liver epithelioid AML were retrieved from our archives from January 2003 to October 2012. The clinicopathologic features of each case were retrospectively reviewed. All 5 patients were female, with age ranging from 36 to 70 years (median, 41 years). The size of the tumor ranged from 1.2 to 25 cm. Histologically, the tumor comprised polygonal cells with granular eosinophilic cytoplasm and accompanied by immunohistochemical expression of HMB-45 ± Melan-A. Variations in growth pattern and cytology were observed. Estrogen receptor was negative in all 5 cases. None showed cytologic atypia, coagulative necrosis, increased mitotic count, or vascular invasion. Epithelioid AML is an uncommon primary liver tumor with a female predominance. The size of the tumor can be variable. This tumor might impose diagnostic difficulty both clinically and histologically. Immunohistochemical staining with melanocytic markers is a promising means to confirm the pathologic diagnosis. A careful assessment of aggressive histologic features is recommended to stratify the risk of aggressive behavior of this tumor.

Differentiating hepatocellular carcinoma from angiomyolipoma of the liver with CT spectral imaging: a preliminary study

AIM

To investigate the value of computed tomography (CT) spectral imaging in differentiating hepatocellular carcinoma (HCC) from angiomyolipoma (AML) during the arterial phase (AP) and portal venous phase (PP).

MATERIALS AND METHOD

Fifty-three patients underwent spectral CT during the AP and PP. Forty-five patients had 45 HCC and eight patients had eight AML. Iodine concentrations in the lesions were normalized to those of the aorta. The normalized iodine concentrations (NIC) and the lesion-normal parenchyma iodine concentration ratio (LNR) were calculated. The two-sample t-test was performed to compare quantitative parameters. Two readers qualitatively assessed lesion types on the basis of imaging features. Sensitivity and specificity were compared between the qualitative and quantitative studies.

RESULTS

NICs and LNRs in patients with HCC differed significantly from those in patients with AML: mean NICs were 0.25 ± 0.06 mg/ml versus 0.59 ± 0.03 mg/ml, respectively, during the AP and 0.52 ± 0.12 mg/ml versus 0.78 ± 0.03 mg/ml, respectively, during the PP. Mean LNRs were 2.97 ± 0.42 versus 5.85 ± 0.43, respectively, during the AP and 0.99 ± 0.17 versus 1.36 ± 0.05, respectively, during the PP. The NICs and LNRs for HCC were lower than those of AML during the AP and PP. The differences were significant (p < 0.05). The threshold NIC and LNR had high sensitivity and specificity in differentiating HCC from AML.

CONCLUSION

CT spectral imaging with the quantitative analysis of iodine concentration may help increase the accuracy of differentiating HCC from AML.

Hepatic angiomyolipoma: a series of six cases with emphasis on pathological-radiological correlations and unusual variants diagnosed by core needle biopsy

Hepatic angiomyolipoma is rare and may pose differential diagnostic difficulty, particularly if encountered in core needle biopsy. We studied 6 cases from 5 males and one female (median age, 48.6 yrs). All presented with non-specific symptoms or an incidentally discovered tumor mass. Two patients had a remote history of chemotherapy for hematological neoplasms (acute lymphoblastic leukemia and Hodgkin lymphoma respectively) and another had clear cell renal cell carcinoma and anaplastic pancreatic carcinoma diagnosed at autopsy without definable syndrome. None of the patients had evidence of the tuberous sclerosis complex or renal or other extra-renal angiomyolipoma. Three tumors were resected completely and three have been only biopsied and followed up. None of the resected cases recurred at a mean follow-up of 35 months. Histologically, tumors were classified as classical triphasic (1), lipomatous (2), epithelioid/oncocytoid (1), epithelioid trabecular (1) and myelolipoma-like (1). The adjacent liver parenchyma was normal in 3 cases, showed pigment cirrhosis in one case and mild fatty change in another case. One case had clinically diagnosed but histologically unverified cirrhosis. The initial diagnostic impression/frozen section was misleading in 5 of the cases and included vascular lesion, focal fatty change, myelolipoma, hepatocellular tumor and oncocytic neoplasm. All tumors expressed HMB45 and variably desmin. One epithelioid lesion expressed HMB45 and TFE3, but lacked desmin expression. In conclusion, hepatic angiomyolipomas are increasingly recognized as incidental findings during surveillance for cirrhosis or investigations for unrelated conditions. Awareness of their diverse morphological spectrum in liver biopsy is necessary to avoid misdiagnosis as hepatocellular carcinoma, metastatic melanoma or other malignant neoplasms.

Hepatic epithelioid angiomyolipoma with trabecular growth pattern: a mimic of hepatocellular carcinoma on fine needle aspiration cytology

Epithelioid angiomyolipomas (AMLs) of the liver are rare tumors with imaging and cytologic features overlapping with those of hepatocellular carcinomas. We report the fine needle aspiration and core biopsy findings of an epithelioid AML in the right hepatic lobe of a 32-year-old female with tuberous sclerosis. She had undergone renal transplantation 8 years previously after bilateral nephrectomy for renal AMLs and a 3-cm chromophobe renal cell carcinoma. Hepatocellular carcinoma was suspected during the initial cytologic and histologic examination based on the presence of numerous large polygonal cells with ample finely vacuolated or granular cytoplasm, low nucleocytoplasmic ratio, and mild nuclear pleomorphism in the smears, as well as a distinctive trabecular histologic pattern in the core biopsies. Immunoperoxidase stains showed that the neoplastic cells were negative for cytokeratins and positive for HMB45, Melan-A, and smooth muscle actin, establishing the diagnosis of epithelioid AML. To determine the distinguishing cytomorphologic features between epithelioid AML and HCC, we have compared the cytologic features of 15 cases of hepatic AML reported in the literature, including the present case, to the FNA cytologic findings of 38 consecutive cases of HCC diagnosed at out institution.

The use of immunohistochemistry in liver tumors

A variety of benign and malignant neoplasms can be encountered in the liver. Hematoxylin and eosin-stained tissue sections alone may not yield sufficient information to definitively diagnose liver tumors; therefore, ancillary studies with immunohistochemical markers can play a crucial role in differentiating the different hepatic neoplasms. The recent development of oncofetoprotein glypican-3 has added to the value of immunohistochemistry in diagnosing liver cancer. This review discusses the immunohistochemical markers used most often in the diagnosis of hepatic tumors.