Epithelioid Hemangioendothelioma

Published on 18/07/2015 by admin

Filed under Radiology

Last modified 22/04/2025

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 Enhancing (hyperemic) peripheral inner rim (increased vascularity)

image Nonenhancing peripheral outer rim or “halo” (avascular rim)
image Delayed or nonenhancing central part of tumor (myxoid and hyalinized stroma)
• Imaging protocol: Multiphasic CT or MR
• Spectrum of growth in lesions may be seen: Nodular form (more common); diffuse or extensive form (very rare)

image  
image  

TOP DIFFERENTIAL DIAGNOSES

• Peripheral cholangiocarcinoma
• Treated malignancy
• Focal confluent fibrosis
• Hemangioma (especially in cirrhotic liver)

PATHOLOGY

• Slowly progressing, low-grade, malignant vascular tumor of liver

image Most patients survive 5-10 years after diagnosis
• Must not be confused with infantile hemangioendothelioma

image Benign primary vascular liver tumor
image Resolves spontaneously in many cases

DIAGNOSTIC CHECKLIST

• Usually located at periphery with extension to capsule
• Typical capsular retraction of peripheral tumor (due to fibrosis and ischemia)

image Rule out other hepatic lesions that typically cause capsular retraction
• “Target” appearance on CECT or MR
• Differentiated from other lesions by tumor cells staining positive for factor VIII-related antigen
image
(Left) Axial CECT shows multiple peripheral, hypovascular lesions image with a “target” appearance (central lucency), typical CT findings of epithelioid hemangioendothelioma (EHE). The subcapsular lesions are associated with retraction of the overlying liver capsule image.

image
(Right) CT of the same patient shows more of the multicentric “target” lesions image typical of EHE, mostly in a peripheral location within the liver.
image
(Left) Gross pathology of the same liver after explantation shows the “target” appearance of the lesions, with necrosis and white fibrous tissue in the center of the lesions, as well as a peripheral rim of compressed parenchyma image and hyperemic tumor.

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(Right) Central portion of EHE typically is hypocellular with loosely arranged spindle cells in a fibromyxoid or sclerotic stroma. The findings can simulate a scar or sclerosed hemangioma. (Courtesy S. Kakar, MD.)

TERMINOLOGY

Abbreviations

• Epithelioid hemangioendothelioma (EHE)

Synonyms

• Hepatic epithelioid hemangioendothelioma

Definitions

• Primary malignant tumor of liver arising from vascular elements of mesenchymal tissue

IMAGING

General Features

• Best diagnostic clue

image Coalescent peripheral hepatic nodules with target-like appearance and capsular retraction
• Location

image Liver

– Periphery (> 75%) with extension to capsule
image Locations other than liver

– Soft tissues, bone, and lung
• Size

image Varies from small tumor nodules to large confluent masses
• Key concepts

image Rare primary malignant (low-grade) vascular tumor of liver in adults
image Other primary malignant vascular tumors of liver

– Angiosarcoma (2% of all primary malignant liver tumors)
– Kaposi sarcoma: Metastatic vascular tumor in AIDS and transplant recipients
image All hepatic malignant vascular tumors

– Share histologic characteristics
– Grow around and into vessels
– Tend to be multifocal
image Clinical course

– Less aggressive than angiosarcomas or hepatocellular carcinoma, but still fatal in most cases
– Variable and unpredictable
– Metastatic in 40% of cases (spleen, mesentery, lymph nodes, lung, bone)

CT Findings

• Spectrum of growth in lesions may be seen

image Nodular form (more common)

– Multiple liver nodules coalesce to form large, confluent masses
image Diffuse or extensive form (very rare)
• Usually located at periphery with extension to capsule
• Capsular retraction (due to tumor fibrosis and ischemia) or flattening; segmental volume loss
• Occasional calcification within tumor
• Compensatory hypertrophy

image Uninvolved liver (usually left lobe)
• May have extrahepatic metastases and ascites
• NECT

image Tumor nodules

– Foci of homogeneous decreased attenuation (due to myxoid stroma) compared to normal liver parenchyma
image Conspicuity and extent of lesions

– CECT superior to NECT
• CECT

image Target-like enhancement pattern of tumor

– Delayed or nonenhancing central part of tumor (myxoid and hyalinized stroma)
– Enhancing (hyperemic) peripheral inner rim (increased vascularity)
– Nonenhancing peripheral outer rim or “halo” (avascular rim)

MR Findings

• T1WI

image Lesions are hypointense centrally
image Peripheral, thin, hypointense rim
• T2WI

image Hyperintense centrally
image Peripheral, thin, hypointense rim
• T1WI C+

image “Target” pattern: 3 concentric layers of alternating signal intensity (analogous to CECT appearance)

– Center: Hypointense
– Periphery: Thick, enhancing, inner rim and thin, nonenhancing, outer rim

Ultrasonographic Findings

• Grayscale ultrasound

image Tumor nodules show varied echogenicity pattern

– Predominantly hypoechoic
– Hyper-/isoechoic lesions may have peripheral hypoechoic rims

Angiographic Findings

• Conventional

image Hypervascular, hypovascular, or avascular lesions

– Based on degree of sclerosis and hyalinization
image Invasion or occlusion of intrahepatic portal and hepatic veins

Imaging Recommendations

• Best imaging tool

image Multiphasic CT or MR
• Protocol advice

image Arterial, venous, delayed phase imaging

DIFFERENTIAL DIAGNOSIS

Peripheral Cholangiocarcinoma

• Heterogeneous mass with capsular retraction
• “Satellite” lesions may be seen

image Usually not as many as with EHE
• Intrahepatic bile duct dilatation

Treated Malignancy

• e.g., hepatocellular carcinoma or metastases
• Capsular retraction
• Heterogeneous enhancement pattern
• History of ablation or chemotherapy for liver tumor
• Treated metastatic nodules may show

image Cystic or necrotic changes
image Debris, mural nodularity
image Thick septa and wall enhancement

Focal Confluent Fibrosis

• Common in advanced cirrhosis
• NECT: Areas of lower attenuation than adjacent liver
• CECT: Isoattenuating or minimally hypo-/hyperattenuating
• MR: Hypointense on T1WI; hyperintense on T2WI
• T1 C+: Isointense or delayed enhancement
• Associated volume loss seen

image Capsular retraction adjacent to lesion
image Segmental or lobar shrinkage
• Usually wedge-shaped lesions radiating from porta affecting anterior and medial segments

Hemangioma (Especially in Cirrhotic Liver)

• Capsular retraction seen in large lesion with scar; hyalinization
• Decrease in size over time as cirrhosis progresses
• Rest of liver shows cirrhotic changes

PATHOLOGY

General Features

• Etiology

image Exact etiology unknown

– Possibly associated with oral contraceptives or exposure to vinyl chloride
• Slowly progressing, low-grade, malignant vascular tumor of liver

image Histology

– Composed of epithelioid-appearing endothelial cells
image Abundant matrix of myxoid and fibrous stroma
image Positive factor VIII-associated antigen staining
image Malignant cells infiltrate into hepatic sinusoids and compress surrounding hepatocytes
image May invade hepatic and portal veins
image Infarction of tumor and central fibrosis
• Must not be confused with infantile hemangioendothelioma

image Histology

– Benign primary vascular liver tumor
image Seen in infants and young children
image Resolves spontaneously in many cases

Gross Pathologic & Surgical Features

• Multiple solid nodules

image Tan, white, firm, varied size
image Nodules coalesce more peripherally
• Tumor nodules with hyperemic rim
• Lesions close to capsule cause retraction

Microscopic Features

• Dendritic spindle-shaped or epithelioid cells
• Matrix: Myxoid or fibrous stroma
• Epithelioid cells

image Stain positive for factor VIII-related antigen

CLINICAL ISSUES

Presentation

• Most common signs/symptoms

image Abdominal pain, jaundice, hepatosplenomegaly
image Rarely, Budd-Chiari syndrome

– Due to hepatic vein invasion
• Laboratory data

image Liver enzymes mildly increased
image α-fetoprotein and CEA levels normal
• Diagnosis

image Tumor cells stain positive for factor VIII-related antigen

Demographics

• Age

image 25-58 years (average: 45 years)
• Gender

image M < F
• Epidemiology

image Rare vascular tumor of liver

– Exact incidence is not known

Natural History & Prognosis

• Complications

image Rupture with hemoperitoneum (very rare)
image Budd-Chiari syndrome
image Liver failure
• Prognosis

image Most patients survive 5-10 years after diagnosis

– 20% die within 1st 2 years after diagnosis
– 20% survive for 5-28 years, ± treatment

Treatment

• Radical resection or liver transplantation

DIAGNOSTIC CHECKLIST

Consider

• Rule out other hepatic lesions that typically cause capsular retraction
• Differentiated from other lesions by tumor cells staining positive for factor VIII-related antigen

Image Interpretation Pearls

• Usually located at periphery with extension to capsule
• Typical capsular retraction of peripheral tumor (due to fibrosis and ischemia)
• “Target” appearance on CECT or MR
image
(Left) Axial CECT in a 30-year-old man with abdominal pain and weight loss shows marked volume loss of the right hepatic lobe, which is essentially replaced by a heterogeneous, hypodense tumor. Other tumors are seen in the left lobe as well image.

image
(Right) Axial CT in the same patient shows additional tumor foci, with capsular retraction evident over at least 1 lesion image.
image
(Left) Lower CT section in the same patient shows more of the confluent tumors and volume loss.

image
(Right) A photograph of the explanted liver shows the yellow-white predominance of fibrotic matrix within the tumors and the peripheral rims of hyperemic tumor and compressed liver image. The capsular retraction over 1 of the peripheral masses is also evident image. The liver itself is not cirrhotic.
image
(Left) Axial CECT in the venous phase shows the classic “target” appearance of EHE image. Note the hypodense center, inner rim of hypervascular enhancement, and outer rim of avascular hypodensity.

image
(Right) Axial T2WI MR in the same patient shows the “target” appearance of EHE image with central hyperintensity, an inner rim of hypointensity, and an outer rim of hyperintensity.
image
(Left) Axial CECT in a 53-year-old man shows multiple hepatic masses that have subtle but important differences in appearance. Multiple hepatic cysts image are of water density and homogeneous; whereas, multiple foci of EHE image are heterogeneous.

image
(Right) In the same patient, again noted are the cysts image and foci of EHE image, many of which are confluent. Multiplicity, peripheral location, confluence, and capsular retraction are all classic features of EHE.
image
(Left) Axial T1WI MR in a 38-year-old woman shows several foci of EHE image, with the typical peripheral location and “target” appearance, with the central fibrotic stroma appearing especially hypointense.

image
(Right) An axial T1WI in the late arterial phase of enhancement shows additional foci of tumor, along with enhancement of only the periphery of the larger tumor foci image.
image
(Left) An axial T2WI MR in the same patient shows the “target” appearance and peripheral location of some of the foci of EHE image, with the fibrous stroma in the center of the tumors being relatively hyperintense.

image
(Right) An additional T2WI shows capsular retraction over 1 of the peripheral foci of EHE image. These are typical clinical and imaging features of hepatic EHE.
image
(Left) Axial CECT in a 38-year-old woman with weight loss shows multifocal tumors image throughout the periphery of both hepatic lobes. Note the confluent tumor in the lateral segment with marked volume loss image.

image
(Right) CT section in the same patient shows the “target” appearance image of some of the tumor foci, consisting of central low density and surrounding layers of relatively high and low density. Note the absence of imaging signs of cirrhosis.
image
(Left) An additional CECT section in the same patient accentuates the peripheral and confluent character of many of the foci of EHE image.

image
(Right) This CT section in the same patient shows the typical spherical shape of the more centrally located tumors image and the hemispheric shape of the subcapsular lesions image.
image
(Left) Coronal reformatted CT in the same patient shows multifocal tumor nodules throughout an otherwise normal liver. Many of the EHE foci are in the hepatic periphery, having a hemispheric shape with flattening of the overlying hepatic capsule image, indicating loss of volume in the affected segments of liver.

image
(Right) An additional coronal CT section in the same patient shows the typical “target” appearance of 1 of the more central foci of EHE image.
image
Gross pathology section of an explanted liver shows multifocal tumor nodules with extensive fibrous stroma, “target” appearance, and capsular retraction.

image
Axial CECT in the venous phase shows multifocal tumor nodules, some with “target” appearance and capsular retraction.

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