CT and MR imaging findings of hepatic epithelioid hemangioendotheliomas: emphasis on single nodular type

Ultrasound findings of hepatic epithelioid hemangioendothelioma: comparison with other malignant hepatic tumors

PURPOSE

To investigate and compare the ultrasonic features of hepatic epithelioid hemangioendothelioma (HEHE) and other common hepatic malignancies, such as hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC) and hepatic metastatic tumor (HMT).

METHODS

A total of 37 patients with pathologically proven HEHE, 37 HCC cases, 37 ICC cases, and 37 HMT cases were enrolled from single hospital. The clinical characteristics and ultrasonic features of all cases were summarized and statistically analyzed.

RESULTS

There were significant differences in sex and age between the HEHE group and other three groups (P < 0.001). The probability of HEHE infection with hepatitis B virus was lower than that of HCC and ICC groups (P < 0.05). The probability of elevated serum tumor markers in HEHE was significantly lower than that in the other three groups (P < 0.05). On conventional ultrasound (CUS), the probability of multiple lesions in HEHE was significantly higher than that in the other three groups (P < 0.05). On contrast-enhanced ultrasound (CEUS), the time to wash out in HEHE was significantly shorter than that of the other three groups (P < 0.001). The proportion of synchronous or slow enhancement in HEHE was significantly higher than that of the other three groups (P < 0.001). The proportion of HEHE with iso- or hypo-enhancement was significantly higher than in HCC and HMT groups (P < 0.05).

CONCLUSION

HEHE mainly performed multiple hypoechoic lesions on CUS and displayed greater odds of synchronous enhancement in arterial phase, iso- or hypo-enhancement in peak time and wash out more quickly on CEUS, which allowed for differentiation from other common malignant tumors.

CT appearances and classification of hepatic epithelioid hemangioendothelioma

BACKGROUND

Hepatic epithelioid hemangioendothelioma (HEH) is extremely rare, and CT features have never been analyzed in a large group of patients.

METHODS

A retrospective study was designed to review the contrast-enhanced CT images of HEH patients. Intrahepatic lesions were categorized into three types: nodular, locally coalescent (coalescent lesion contained in one segment) or diffusely coalescent (coalescent lesion occupied more than one segment). CT features were compared among lesions of different sizes and patients with different lesion types.

RESULTS

A total of 93 HEH patients were included in this study, and 740 lesions were analyzed. The results of per-lesion analysis showed that medium lesions (2-5 cm) had the highest rate of lollipop sign (16.8%) and target-like enhancement (43.1%), while lesions in large group (> 5 cm) had the highest rate of capsular retraction (38.8%) and vascular invasion (38.8%). The differences on enhancement pattern and the rates of lollipop sign and capsular retraction were significant among lesions of different sizes (p < 0.001, respectively). The results of per-patient analysis showed that patients in locally coalescent group had the highest rates of lollipop sign (74.3%) and target sign (94.3%). All patients in diffusely coalescent group had capsular retraction and vascular invasion. CT appearances of capsular retraction, lollipop sign, target sign and vascular invasion differed significantly among patients with different lesion types (p < 0.001, p = 0.005, p = 0.006 and p < 0.001, respectively).

CONCLUSION

CT features variated among HEH patients with different lesion types, and radiological appearances of HEH should be classified into nodular type, locally coalescent type and diffusely coalescent type.

CT and MRI features of hepatic epithelioid haemangioendothelioma: a multi-institutional retrospective analysis of 15 cases and a literature review

OBJECTIVE

To improve the current imaging understanding of MRI or CT for hepatic epithelioid haemangioendothelioma (HEHE) to aid in its successful preoperative diagnosis.

METHODS

The imaging features of 15 patients (median age 38.6, range 20-71; 7 M/8 F) from eight institutions with pathologically confirmed HEHE were retrospectively analysed. Additionally, the CT/MR imaging features of 180 patients in 15 literature publications were collected, analysed and compared with our case series.

RESULTS

Fifteen patients underwent CT and MRI (n = 2), CT (n = 9) or MR (n = 8) scans. A total of 92.9% (13/14) of the patients were initially diagnosed with other lesions on imaging. A total of 86.7% (13/15) were multifocal. Nodules (11/15, 73.3%) were predominantly peripheral in distribution (12/15, 80.0%). Some cases were associated with hepatic capsular retraction (13/15, 86.7%), "target signs" (8/15, 53.3%) and "lollipop signs" (5/15, 33.3%). Peripheral enhancement of various shapes in the early phase with a progressive centripetal filling was the most common pattern of enhancement (12/15, 80.0%). Abnormal vascularity was seen in 50.7% (6/15) of the patients. Suspicious tumour thromboses in the inferior vena cava were seen in 3 (20.0%) of the patients. Two of the 15 patients (13.3%) had a history of smoking.

CONCLUSIONS

HEHEs have common distinctive features, including multifocal lesions that are predominantly peripheral, "target signs", "lollipop signs", hepatic capsular retraction and peripheral enhancement of various shapes in the early phase with progressive centripetal filling. Additional aggressive imaging features that may be valuable clues to the diagnosis can be identified by CT or MRI.

MRI appearances of hepatic epithelioid hemangioendothelioma: a retrospective study of 57 patients

Background

Hepatic epithelioid hemangioendothelioma (HEH) is extremely rare and the MRI features have never been investigated in a large group of patients.

Methods

A retrospective study was designed to review the MRI images of HEH patients. Two radiologists separately evaluated signal intensity (SI) on unenhanced imaging, morphological features, contrast-enhancement pattern at dynamic study. The MRI features were compared between patients with HEH and hepatic metastatic tumor (HMT).

Results

Fifty-seven HEH patients were included in this study and a total of 412 lesions were evaluated. On per-lesion analysis, the rate of coalescent lesion and subcapsular lesion were 18.2% and 39.8%, respectively. Capsular retraction and lollipop sign were observed in 47 lesions (11.4%) and 60 lesions (14.6%), respectively. Large lesions (> 5 cm) had the highest rate of coalescent lesion, subcapsular lesion, capsular retraction and lollipop sign. Target sign appeared in 196 lesions (47.6%) on T2 weighted (T2W) and 146 lesions (35.4%) on portal phase. Medium lesions (2–5 cm) had the highest rate of target sign on both T2W (72.9%) and portal phase (55.2%). On per-patient analysis, compare with HEH patients, HMT patients seldom had the appearance of lollipop sign (66.7% versus 6.4%, p < 0.01), capsular retraction (59.6% versus 3.2%, p < 0.01) and target appearance on both T2Wand portal phase (64.9% versus 12.7%, p < 0.01).

Conclusion

MRI features of HEH correlated with the lesion size. Capsular retraction, lollipop sign and coexistence of target sign on both T2W and portal phase were relatively specific MRI features of HEH, which could be helpful in suggesting the diagnosis.

Imaging Spectrum of Intrahepatic Mass-Forming Cholangiocarcinoma and Its Mimickers: How to Differentiate Them Using MRI

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary hepatic malignancy, with mass-forming growth pattern being the most common. The typical imaging appearance of mass-forming ICC (mICC) consists of irregular ring enhancement in the arterial phase followed by the progressive central enhancement on portal venous and delayed phases. However, atypical imaging presentation in the form of hypervascular mICC might also be seen, which can be attributed to distinct pathological characteristics. Ancillary imaging features such as lobular shape, capsular retraction, segmental biliary dilatation, and vascular encasement favor the diagnosis of mICC. Nevertheless, these radiological findings may also be present in certain benign conditions such as focal confluent fibrosis, sclerosing hemangioma, organizing hepatic abscess, or the pseudosolid form of hydatid disease. In addition, a few malignant lesions including primary liver lymphoma, hemangioendothelioma, solitary hypovascular liver metastases, and atypical forms of hepatocellular carcinoma (HCC), such as scirrhous HCC, infiltrative HCC, and poorly differentiated HCC, may also pose a diagnostic dilemma by simulating mICC in imaging studies. Diffusion-weighted imaging and the use of hepatobiliary contrast agents might be helpful for differential diagnosis in certain cases. The aim of this manuscript is to provide a comprehensive overview of mICC imaging features and to describe useful tips for differential diagnosis with its potential mimickers.

Clinical characteristics and CT features of hepatic epithelioid haemangioendothelioma and comparison with those of liver metastases

BACKGROUND

To analyse clinical characteristics and computer tomography (CT) findings of hepatic epithelioid haemangioendothelioma (HEH) and to determine differential features compared with liver metastasis (LM).

METHODS

This retrospective study included 80 patients with histopathologically confirmed HEH (n = 20) and LM (n = 60) of different primary tumours who underwent dynamic contrast-enhanced CT scans. CT findings included the location, contour, size, number, margin, and density of lesions, the patterns and degree of contrast enhancement of lesions, vascular invasion and changes in other organs. The enhancement ratio (ER) and tumour-to-normal parenchyma ratio (TNR) were calculated. Receiver operating characteristic curves (ROCs) were used to determine areas under the curve (AUCs).

RESULTS

About 65% of HEH lesions were located in submarginal areas. Significant differences were observed between HEH and LM patients in age, sex, and tumour marker positivity (p < 0.05). HEH showed minimal to slight enhancement, thin ring-like enhancement in arterial phase, and slight, homogeneous, progressive enhancement in the portal phase. HEH presented capsule retraction, and the "target" sign and the "lollipop" sign were significantly more frequent than in LM (p < 0.05). The ER and TNR in the arterial phase of HEH were lower than those of LM (p < 0.05). AUCs of ER and TNR in the arterial phase were 0.74 and 0.73, respectively.

CONCLUSION

Lesions in subcapsular locations, capsular retraction, slight and thin ring-like enhancement, "target" and "lollipop" signs and lower ER and TNR in the arterial phase may represent important features of HEH compared with LM.

Conventional Ultrasound and Contrast-Enhanced Ultrasound in Hepatic Epithelioid Hemangioendothelioma: Retrospective Evaluation in 20 Cases

OBJECTIVES

This study aimed to analyze the patterns of conventional ultrasound (CUS) and contrast-enhanced ultrasound (CEUS) in 20 patients with diagnosis of hepatic epithelioid hemangioendothelioma (HEHE).

METHODS

Twenty patients (12 females and 8 males) with mean age of 43.6 ± 13.6 years were included in this study from January 2012 to May 2020. CUS, CEUS, computed tomography (CT) and magnetic resonance imaging (MRI) features of the twenty patients with histologically proven HEHE were retrospectively reviewed by two radiologists. The clinical manifestations and the pathological findings of all patients with HEHE are described.

RESULTS

There were 3 types of HEHE in imaging, including single nodular (8/20, 40%), multifocal nodular (10/20, 50%), and diffuse type (2/20, 10%). The mean size of lesions was 4.2 ± 2.6 cm. B-mode ultrasound of HEHE showed hypoechoic (15/20, 75%), heterogeneous echogenicity (4/20, 20%), or hyperechoic (1/20, 5%) lesions with regular shape (18/20, 90%) near the liver capsule (17/20, 85%), and occasionally with a halo (4/20, 20%) and calcifications (3/20, 15%). Eight out of the 20 patients also had CEUS. On CEUS, HEHE demonstrated peripheral rim-like (5/8, 62.5%), heterogeneous (2/8, 25%), or homogeneous (1/8, 12.5%) hyperenhancement in the arterial phase. All patients (8/8, 100%) showed hypoenhancement in the portal and late phase. CEUS detected more lesions than CUS in 3 patients (3/8, 37.5%). In addition, central irregular unenhanced zones were observed in 6 patients (6/8, 75%). On contrast-enhanced CT or MRI, most cases presented with capsule retraction sign and lollipop sign.

CONCLUSIONS

HEHE demonstrated specific findings on ultrasound, which includes multifocal hypoechoic lesions in a subcapsular distribution with typical enhancement characteristics of malignant hepatic tumors.

Epithelioid hemangioendothelioma, an ultra-rare cancer: a consensus paper from the community of experts

Epithelioid hemangioendothelioma (EHE) is an ultra-rare, translocated, vascular sarcoma. EHE clinical behavior is variable, ranging from that of a low-grade malignancy to that of a high-grade sarcoma and it is marked by a high propensity for systemic involvement. No active systemic agents are currently approved specifically for EHE, which is typically refractory to the antitumor drugs used in sarcomas. The degree of uncertainty in selecting the most appropriate therapy for EHE patients and the lack of guidelines on the clinical management of the disease make the adoption of new treatments inconsistent across the world, resulting in suboptimal outcomes for many EHE patients. To address the shortcoming, a global consensus meeting was organized in December 2020 under the umbrella of the European Society for Medical Oncology (ESMO) involving >80 experts from several disciplines from Europe, North America and Asia, together with a patient representative from the EHE Group, a global, disease-specific patient advocacy group, and Sarcoma Patient EuroNet (SPAEN). The meeting was aimed at defining, by consensus, evidence-based best practices for the optimal approach to primary and metastatic EHE. The consensus achieved during that meeting is the subject of the present publication.

•

This consensus paper provides key recommendations on the management of epithelioid hemangioendothelioma (EHE).

•

Recommendations followed a consensus meeting between experts and a representative of the EHE advocacy group and SPAEN.

•

Authorship includes a multidisciplinary group of experts from different institutions from Europe, North America and Asia.

Laparoscopic repeat liver resection for hepatic epithelioid hemangioendothelioma

BACKGROUND

Optimal treatment for patients with hepatic epithelioid hemangioendothelioma (HEHE) remains unclear. Laparoscopic repeat liver resection (LR) is a minimally invasive and potentially effective surgical option for multiple HEHEs.

CASE PRESENTATION

A 42-year-old woman with no relevant history was admitted for multiple liver tumors. Six tumors were observed on T2-weighted magnetic resonance imaging (MRI) including one in S2, two in S3, two in S7, and one in S8. Pathological evaluation of percutaneous tumor biopsy tissue suggested a diagnosis of HEHE and laparoscopic LR was planned. The procedure began with partial resection of S7 and partial resection of S8 and left lateral sectionectomy were performed. Another tumor was found intraoperatively on the surface of S6, necessitating removal by partial resection. Pathological evaluation of the resected tumor tissue from all seven tumors concurred with that of the preoperative biopsy. The patient was discharged on postoperative day 6 without any complications. A follow-up MRI 15 months after the primary surgery revealed one tumor each in S4, S6, and S8. Laparoscopic repeat LR was performed. The patient was discharged on postoperative day 5 without any complications. All three recurrent tumors were pathologically confirmed as HEHEs.

CONCLUSIONS

We successfully treated primary and recurrent HEHEs with laparoscopic LR, which is a reasonable minimally invasive procedure considering the possibility of multiple courses of liver surgery in patients with HEHE.

Comparison of the clinical and MRI features of patients with hepatic hemangioma, epithelioid hemangioendothelioma, or angiosarcoma

Background

Comparisons of hepatic epithelioid hemangioendothelioma (HEHE), hepatic hemangioma, and hepatic angiosarcoma (HAS) have rarely been reported. The purpose of our study was to analyze the clinical and magnetic resonance imaging (MRI) findings of these conditions.

Methods

A total of 57 patients (25 with hemangioma, 13 with HEHE, and 19 with HAS) provided hepatic vascular endothelial cell data between June 2006 and May 2017.

Results

The proportions of cases with circumscribed margins were 88% (22/25), 84.6% (11/13), and 31.6% (6/19) for hemangioma, HEHE, and HAS, respectively (P < 0.001). HAS lesions were less likely to have circumscribed margins. The proportions of lesions with hemorrhaging were 4% (1/25), 30.8% (4/13), and 36.8% (7/19) for hemangioma, HEHE, and HAS, respectively (P = 0.014). HEHE and HAS cases were more likely to show heterogeneous signals on T1-weighted (T1WI) MRI. HEHE and HAS cases were more likely to show heterogeneous signals on T2-weighted (T2WI) MRI. Centripetal enhancement was the most common pattern in vascular tumors, with proportions of 100, 46.2% (6/13), and 68.4% (13/19) for hemangioma, HEHE, and HAS, respectively. The difference in enhancement pattern between HEHE and HAS was not significant, but rim enhancement was more common for HEHE (46.2%, 6/13).

Conclusions

Our study revealed clinical and imaging differences between HEHE and HAS. The platelet count (PLT) and coagulation function of the HAS group decreased, whereas the alpha-fetoprotein (AFP) level increased. The 5-year survival rate for HAS was significantly lower than that of HEHE. A higher malignancy degree indicated a more blurred lesion margin, easier occurrence of hemorrhaging, and more heterogeneous T1WI and T2WI signals.

Hepatic hemangioendothelioma: CT, MR, and FDG-PET-CT in 67 patients-a bi-institutional comprehensive cancer center review

OBJECTIVE

To evaluate the imaging features of hepatic epithelioid hemangioendothelioma (HEH) on multiphasic CT, MR, and FDG-PET-CT.

METHODS

Bi-institutional review identified 67 adults (mean age, 47 years; 23 M/44 F) with pathologically proven HEH and pretreatment multiphasic CT (n = 67) and/or MR (n = 30) and/or FDG-PET-CT (n = 13).

RESULTS

HEHs were multifocal in 88% (59/67). Mean size of the dominant mass was 4.1 cm (range, 1.4-19 cm). The tumors were located in the peripheral, subcapsular regions of the liver in 96% (64/67). Capsular retraction was present in 81% (54/67 cases) and tumors were coalescent in 61% (41/67). HEH demonstrated peripheral ring enhancement on arterial phase imaging in 33% (21/64) and target appearance on the portal venous phase in 69% (46/67). Persistent peripheral enhancement on the delayed phase was seen in 49% (31/63). On MR, multilayered target appearance was seen on the T2-weighted sequences in 67% (20/30) and on the diffusion-weighted sequences in 61% (11/18). Target appearance on hepatobiliary phase of MRI was seen in 57% (4/7). On pre-therapy FDG-PET-CT, increased FDG uptake above the background liver parenchyma was seen in 62% (8/13).

CONCLUSION

HEHs typically manifest as multifocal, coalescent hepatic nodules in peripheral subcapsular location, with associated capsular retraction. Peripheral arterial ring enhancement and target appearance on portal venous phase are commonly seen on CT. Similarly, multilayered target appearance correlating with its histopathological composition is typically seen on multiple sequences of MR including T2-weighted, diffusion-weighted, and dynamic contrast-enhanced multiphasic MR.

KEY POINTS

• Hepatic epithelioid hemangioendotheliomas manifest on CT and MR as multifocal, coalescent hepatic nodules in peripheral subcapsular location, with associated capsular retraction. • Enhancement pattern on contrast-enhanced CT and MR can vary but peripheral ring enhancement on arterial phase and target appearance on portal venous phase are commonly seen. • Retrospective two-center study showed that cross-sectional imaging may help in the diagnosis.

Three cases of histologically proven hepatic epithelioid hemangioendothelioma evaluated using a second-generation microbubble contrast medium in ultrasonography: case reports

Background

Hepatic epithelioid hemangioendothelioma (HEH) is rare; it is reported in < 1 person in 1,000,000 individuals. For accurate diagnosis, information regarding multiple graphic modalities in HEH is required. However, there is very little information concerning Sonazoid® contrast enhanced ultrasonography (CEUS) in HEH.

Case presentation

The present report describes the histologically proven three HEH cases evaluated using Sonazoid® CEUS. Case 1 was a 33-year-old female patient with no relevant past medical history, who experienced right upper quadrant pain. Conventional abdominal US revealed multiple low echoic liver nodules with vague borderlines. In CEUS, the vascularity of the nodules was similar to that seen in the neighboring normal liver. Later in the portal venous and late phases (PVLP) and post vascular phase, washout of Sonazoid® was detected in the nodules. Case 2 was a 93-year-old female patient with a previous medical history including operations for breast cancer and ovary cancer in her 50’s. Conventional abdominal US revealed multiple low echoic nodules, some of which contained cystic lesions. In the early vascular phase of CEUS, nodules excluding the central anechoic regions were enhanced from peripheral sites. Although the enhancement inside the nodules persisted in both the PVLP and post vascular phase, anechoic areas in the center of some nodules were not enhanced at all. Case 3 was a 39-year-old male patient presented with right upper-quadrant pain, without any relevant past medical history. Conventional abdominal US revealed multiple low echoic liver nodules. In the early vascular phase of CEUS, nodules were gradually enhanced from the peripheral sites as ringed enhancement. Sonazoid®was washed out from the nodules in the PVLP and post vascular phase.

Conclusions

The most important feature was peripheral enhancement in the early vascular phase. In case 2, the enhancement of the parenchyma of liver nodules persisted even in the PVLP; indicating the lower degree of malignant potential than others. Actually, the tumors did not extend without any treatment in case 2. Since case 2 is the first case report of HEH with cystic lesions, in patients with liver nodules including cystic lesions, HEH is a potential diagnosis.

[Epithelioid hemangioendothelioma]

We describe herein the inaugural manifestations, the radiological and histological diagnosis criteria for and the outcome of epithelioid hemangioendothelioma (EHE). Most of EHE (90%) display a specific reciprocal chromosomic translocation t(1;3)(p36;q23-25), which is associated with the synthesis of fusion protein WWTR1/CAMTA1. EHE are low-grade vascular sarcomas. EHE could be initially localized or multifocal. At localized stage, EHE are best treated with focal treatments. At multifocal stage, the upfront strategy is watchful follow-up. Some multifocal EHE display very indolent course with spontaneous stable disease for years or decades. In case of progressive multifocal EHE, there is no consensual treatment. Diagnostic and clinical management of EHE requires interdisciplinary expertise from labeled centers.

Hepatic tumors of vascular origin: imaging appearances

A number of benign and malignant neoplasms may arise from the vascular elements within the liver parenchyma. Lesions discussed in this article include angiosarcoma, epithelioid hemangioendothelioma, solitary fibrous tumor (hemangiopericytoma), infantile, and cavernous hemangiomas. Despite a common theme of vascular origin, the pathologic and imaging appearance of these entities can be heterogeneous. Angiosarcomas are bizarrely enhancing, highly aggressive tumors, which often present with metastatic disease. When solitary, epithelioid hemangioendothelioma lesions can exhibit a concentric ring or target appearance on contrast-enhanced CT and at MR and when numerous may be indistinguishable from angiosarcoma except for a more slowly advancing course. Primary solitary fibrous tumors of the liver are exceedingly rare solid masses and most often initially diagnosed on imaging as other entities such as cholangiocarcinoma. Infantile hemangiomas consist of benign proliferation of the vascular endothelium and in the absence of flow-related complications, are usually clinically silent, and may be detected incidentally as T1 hypointense, T2 hyperintense, centripetally enhancing lesions. Cavernous hemangiomas are extremely common hepatic lesions and when classic rarely offer a challenge in diagnosis, though atypical variants may mimic more serious diseases. The purpose of this review is to provide an overview of important vascular tumors of the liver in order to aid the radiologist in providing a broad differential diagnosis for focal liver lesions, and when classic, suggest specific uncommonly seen diagnoses in order to more accurately guide clinical management.

Imaging features of rare mesenychmal liver tumours: beyond haemangiomas

Tumours arising from mesenchymal tissue components such as vascular, fibrous and adipose tissue can manifest in the liver. Although histopathology is often necessary for definitive diagnosis, many of these lesions exhibit characteristic imaging features. The radiologist plays an important role in suggesting the diagnosis, which can direct appropriate immunohistochemical staining at histology. The aim of this review is to present clinical and imaging findings of a spectrum of mesenchymal liver tumours such as haemangioma, epithelioid haemangioendothelioma, lipoma, PEComa, angiosarcoma, inflammatory myofibroblastic tumour, solitary fibrous tumour, leiomyoma, leiomyosarcoma, Kaposi sarcoma, mesenchymal hamartoma, undifferentiated embryonal sarcoma, rhabdomyosarcoma and hepatic metastases. Knowledge of the characteristic features of these tumours will aid in guiding the radiologic diagnosis and appropriate patient management.

Primary Hepatic Neoplasms of Vascular Origin: Key Imaging Features and Differential Diagnoses With Radiology-Pathology Correlation

OBJECTIVE

This article describes, illustrates, and correlates imaging and pathologic features of primary vascular mesenchymal neoplasms of the liver, which arise from the vascular endothelium and perivascular epithelioid cells.

CONCLUSION

Familiarity with the spectrum of benign, malignant-potential and malignant vascular neoplasms, and nonneoplastic mimickers allows consideration in the differential diagnosis of enhancing hepatic masses. Understanding relevant pathologic features facilitates recognition of key imaging features, specifically dynamic contrast enhancement patterns on CT and MRI, which provide a useful classification system.

Magnetic Resonance Imaging of Primary Hepatic Malignancies in Patients With and Without Chronic Liver Disease: A Pictorial Review

Primary hepatic malignancies are less common than metastatic diseases, but a recognition of these lesions is important for diagnosis and treatment planning. Magnetic resonance imaging (MRI) provides the most imaging information to diagnose lesions noninvasively and to narrow differential diagnoses. This paper reviews the imaging findings of chronic liver disease and primary hepatic malignancies, including hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (CCA), epithelioid hemangioendothelioma, hepatic angiosarcoma, and primary hepatic lymphoma. Clinical and MRI features are reviewed to improve the readers’ recognition of these tumors, allowing for a narrower differential diagnosis when liver masses are encountered on abdominal imaging.

A Pictorial Review of Hepatobiliary Magnetic Resonance Imaging With Hepatocyte-Specific Contrast Agents: Uses, Findings, and Pitfalls of Gadoxetate Disodium and Gadobenate Dimeglumine

Magnetic resonance imaging (MRI) has a well-established role as a highly specific and accurate modality for characterizing benign and malignant focal liver lesions. In particular, contrast-enhanced MRI using hepatocyte-specific contrast agents (HSCAs) improves lesion detection and characterization compared to other imaging modalities and MRI techniques. In this pictorial review, the mechanism of action of gadolinium-based MRI contrast agents, with a focus on HSCAs, is described. The clinical indications, protocols, and emerging uses of the 2 commercially available combined contrast agents available in the United States, gadoxetate disodium and gadobenate dimeglumine, are discussed. The MRI features of these agents are compared with examples of focal hepatic masses, many of which have been obtained within the same patient therefore allowing direct lesion comparison. Finally, the pitfalls in the use of combined contrast agents in liver MRI are highlighted.

Uncommon liver tumors: Case report and literature review

BACKGROUND

Beside hepatocellular carcinoma, metastasis, and cholangiocarcinoma, the imaging findings of other relatively uncommon hepatic lesions are less discussed in the literature. Imaging diagnosis of these lesions is a daily challenge. In this article, we review the imaging characteristics of these neoplasms.

METHODS

From January 2003 to December 2014, 4746 patients underwent liver biopsy or hepatic surgical resection in our hospital. We reviewed the pathological database retrospectively. Imaging of these lesions was reviewed.

RESULTS

Imaging findings of uncommon hepatic lesions vary. We discuss the typical imaging characteristics with literature review. Clinical and pathological correlations are also described. Primary hepatic lymphoma consists only of 1% of the extranodal non-Hodgkin lymphoma, and is defined as the one involving only the liver and perihepatic lymph nodes within 6 months after diagnosis. Combined hepatocellular and cholangiocarcinoma (cHCC-CC) shares some overlapping imaging characteristics with both HCC and cholangiocarcinoma because of being an admixture of them. Angiosarcoma is the most common hepatic mesenchymal tumor and is hypervascular in nature. Inflammatory pseudotumor is often heterogeneous on ultrasonography and with enhanced septations and rims in the portovenous phase after contrast medium. Angiomyolipoma (AML) typically presents with macroscopic fat components with low signal on fat-saturated magnetic resonance imaging (MRI) and presence of drainage vessels. Intraductal papillary neoplasm of the bile duct (IPNB) is thought of as a counterpart to the pancreatic intraductal papillary mucinous neoplasm. Most of the IPNBs secrete mucin and cause disproportional dilatation of the bile ducts. Mucinous cystic neoplasm (MCN) contains proteinaceous and colloidal components without ductal communication and characterizes with hyperintensity on T1-weighted imaging. Other extremely rare lesions, including epithelioid hemangioendothelioma and inflammatory pseudotumor-like follicular dendritic cell sarcoma, are also discussed. Hepatoblastoma and mesenchymal hamartoma, mostly in children, are also briefly reviewed as well.

CONCLUSION

It is important for radiologists to be familiar with the typical imaging features of the uncommon hepatic neoplasms. If imaging findings are not typical or diagnostic, further biopsy is required.

Contrast-enhanced ultrasound of histologically proven hepatic epithelioid hemangioendothelioma

AIM: To analyze contrast-enhanced ultrasound (CEUS) features of histologically proven hepatic epithelioid hemangioendothelioma (HEHE) in comparison to other multilocular benign focal liver lesions (FLL).

METHODS: Twenty-five patients with histologically proven HEHE and 45 patients with histologically proven multilocular benign FLL were retrospectively reviewed. Four radiologists assessed the CEUS enhancement pattern in consensus.

RESULTS: HEHE manifested as a single (n = 3) or multinodular (n = 22) FLL. On CEUS, HEHE showed rim-like (18/25, 72%) or heterogeneous hyperenhancement (7/25, 28%) in the arterial phase and hypoenhancement (25/25, 100%) in the portal venous and late phases (PVLP), a sign of malignancy. Eighteen patients showed central unenhanced areas (18/25, 72%); in seven patients (7/25, 28%), more lesions were detected in the PVLP. In contrast, all patients with hemangioma and focal nodular hyperplasia showed hyperenhancement as the most distinctive feature (P < 0.01).

CONCLUSION: CEUS allows for characterization of unequivocal FLL. By analyzing the hypoenhancement in the PVLP, CEUS can determine the malignant nature of HEHE.

Typical CT and MRI signs of hepatic epithelioid hemangioendothelioma

To investigate the typical magnetic resonance imaging (MRI) and computed tomography (CT) features of hepatic epithelioid hemangioendothelioma (HEH), the CT and MRI findings of 14 histopathologically confirmed cases of HEH were retrospectively analyzed. Non-contrast and dynamic contrast-enhanced scans were conducted in all cases. A total of 229 lesions were detected in the 14 cases. All cases were classified as one of three types: (i) Solitary nodular type (1 case, 7%); (ii) multifocal nodular type (11 cases, 79%); or (iii) diffuse type (2 cases, 14%). The diameter of the lesions ranged from 5 to 105 mm. For the first two types (solitary and multifocal nodular types), the CT findings included low density lesions with clear margins on non-contrast scans, centripetal enhancement in arterial phase, and homogeneous enhancement in the portal venous and delay phases. The findings of non-contrast MRI scans for these two types included low signal intensity on T1-weighted images, heterogeneous high signal intensity on T2-weighted images, and heterogeneous high signal intensity on diffusion-weighted images. The lesions were predominantly located in submarginal areas. On contrast-enhanced MRI, the findings for the first two types included peripheral ring-like enhancement with a central low signal intensity (‘black target-like’ sign) and a central enhanced core surrounded by a low signal intensity halo (‘white target-like’ sign). The findings for the third HEH type (diffuse type) on CT and MRI scans included low density or heterogeneous signal intensity lesions involving regions of part or the whole liver, coalescent lesions (‘strip-like’ sign), and gradual enhancement along central vessels (‘lollipop’ sign). Collectively, these findings indicate that the ‘white target-like’ sign, ‘black target-like’ sign, ‘lollipop’ sign and ‘strip-like’ sign, in addition to capsular contraction and submarginal location, on CT and MRI imaging may have implications for the diagnosis of HEH. Furthermore, a variety of MRI sequences may provide additional information for the differential diagnosis of HEH.