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7 Rare Benign Liver Tumors
199
a
c
b
d
Fig. 7.6 A large cystic hepatic biliary cystadenoma (HBCA) lesion. On B mode ultrasound, thin hyperechoic spates could be detected inside the
lesion (a). After injection of contrast agents, the septa showed isoenhancement during arterial (b), portal venous (c), and late phases (d)
– The septation without nodularity suggests the diagno-
sis of HBCA.
• Contrast enhanced ultrasound
• Contrast enhanced ultrasound can show the characteristics of blood supply in HBCA.
– Enhancement appearances during arterial phase (10–
30 s), portal venous (30–120 s), and late vascular
phases (120–300s) should be evaluated in liver cystic
or cystic-solid lesion.
– Contrast enhanced ultrasound showing isoenhance-
ment honeycomb septa during portal venous and late
phase might suggest HBCA.
• CT
– HBCA often appears as a solitary cystic mass with a
well-dened thick brous capsule. Internal septa, and
rarely capsular calcication and mural nodularity
could be found inside the lesion.
– HBCA lesions are iso-density to water (less than
30 HU) with cyst wall and internal septa enhancing
with intravenous contrast.
• MRI
– HBCA signal characteristics are typical for uid-
containing cystic lesion, including homogeneous
hypo- or iso-signal on T1-weighted images.
– Linear low signal intensity within high-intensity cysts
identies septations on T2-weighted images.
– The internal uid within the HBCA can be detected as
varied signal intensity on T1- and T2-weighted images
due to differences in the presence of solid components,
protein content and hemorrhage.
200
P.-L. Fan et al.
– MRCP can clearly and intuitively displays intrahepatic
bile ducts and can also demonstrate cysts is not communicate with the biliary tree and identify internal septations.
– MRCP images possibly show a ductal dilatation
upstream to cystic lesion.
– The addition of diffusion-weighted MR to conven-
tional MRI sequences aids in the assessment of focal
liver lesions with improved cyst characterization.
• The combination of ultrasound, CT, and MRI imaging
modalities can help diagnose HBCT with signicantly
improved diagnostic accuracy.
7.2.3 Dierential Diagnosis
7.2.3.1 Hepatic Biliary Cystadenocarcinoma
• Hepatic biliary cystadenocarcinoma is a malignant lesion
with more solid components in the cystic mass and uneven
thickness of the cyst wall.
• Hepatic biliary cystadenocarcinoma is more likely to contain mural or septal nodules and papillary projections
inside.
• The protruding masses in the cysts are often large and
numerous, cauliower-shaped.
• A nodule diameter >10 mm and the calcications along
the wall and internal septum are suggestive of hepatic
biliary cystadenocarcinoma.
• Papillary excrescence, nodular thickening of internal
septa, and mural nodules are signicant contrast enhancement in hepatic biliary cystadenocarcinoma.
• Dilated biliary ducts around the mass are more often seen
in hepatic biliary cystadenocarcinoma than in HBCA.
7.2.3.2 Simple Hepatic Cyst
• It shows as smooth boundary and thin capsule wall and
lack of internal septations and papillary projections.
• In enhanced imaging, the capsule wall is no
enhancement.
• If the cyst is complicated by infection, the cyst wall can
also be seen to be thickened and strengthened, and the
density/signal of the cyst uid is uneven, which is difcult
to identify, and it needs to be comprehensively analyzed
in combination with clinical history and laboratory tests.
7.2.3.3 Hemorrhagic Hepatic Cysts
• Ultrasound can detect irregular cystic clots and nodular
septal images.
• It homogenously decreases in spatial resolution on CT
imaging.
• High signal on T1 and low signal on T2-weighted images
from clot formation are also seen on MRI.
7.2.3.4 Metastatic Tumor
• Most metastatic tumors have a clear history of the primary tumor.
• The lesion can be necrotic showing as a cystic tumor
without multilocular septa.
• The cyst wall is thick and irregular with ring enhancement, typically showing “bull’s eye sign.”
7.2.3.5 Hepatic Abscesses
• It has typical clinical symptoms, fever, and other infection
symptoms.
• Ring enhancement in thick-wall, circular edema bands
around the focus, enhanced abscess walls, and peripheral
non-reinforced edema bands constitute “target ring sign”
can be seen on enhanced CT.
• Signicant increase in white blood cells is a typical biochemical manifestation.
• The septations characteristic of cystadenomas are uncommon in abscesses.
7.2.3.6 Hydatid Disease
• It is typically caused by Echinococcus granulosis in animal husbandry area.
• Typical CT manifestations are multi-lobular appearance
with the daughter cysts in the original cyst.
• If the inner walls of the cysts rupture, it shows as “water
oating lotus” sign, part of the cysts may be accompanied
by arc-shaped calcication.
• If necessary, diagnosis will be combined with laboratory
tests.
7.2.3.7 Biliary Intraductal Papillary Mucinous
Neoplasm
• It occurs more commonly among Asians. The clinical and
imaging manifestations of the biliary intraductal papillary
mucinous neoplasm and HBCA are very similar.
• The papillary projections are typical in biliary intraductal
papillary mucinous neoplasm and less in HBCA.
• The biliary intraductal papillary mucinous neoplasm does
not contain ovarian stroma.
• Demonstration of cystic mass and intrahepatic bile duct
communication along with the presence of distal mucin is
the characteristic of biliary intraductal papillary mucinous neoplasm.
• Most Biliary intraductal papillary mucinous neoplasms
have the dilatation of the bile ducts and are also prone to
gallstone.
7.2.3.8 Undierentiated Embryonal Sarcoma
• A typical undifferentiated embryonal sarcoma appears as
a large, solitary, and predominantly cystic mass with a
7 Rare Benign Liver Tumors
201
clear border. Occasionally, a pseudocapsule separates the
mass from the surrounding normal liver parenchyma.
• Large portions of the mass are hypointense on
T1-weighted images and hyperintense on T2-weighted
images of MRI.
• On contrast-enhanced CT and MRI images, heterogeneous enhancement is present in the solid, usually peripheral portions of the mass, especially on delayed images.
• They have multiloculated cystic appearance but are generally seen in children and young adults.
7.2.3.9 Mesenchymal Hamartoma
• Mesenchymal hamartoma of the liver are uncommon
benign tumors.
• It has very similar to cystadenomas, but it is most often
seen in infants less than 2 years of age.
7.2.4 Pathology
7.2.4.1 General Features
• HBCA shows as a unilocular or multilocular welldemarcated cystic mass with smooth brous capsules,
and smooth, nely granular, or trabeculated inner surfaces
and usually thin septa.
• The description of HBCA is characterized by three distinct
layers: (1) an epithelial layer of mucin-producing cells; (2)
a layer of undifferentiated mesenchymal cells under the epithelial lining, and (3) a dense layer of collagenous connective tissue outside the stromal bands of cells.
• The uid in the cysts can be proteinaceous, mucinous, and
occasionally purulent, gelatinous, or hemorrhagic.
• Composition of uid can be different in different compartments of HBCA cyst.
• The epithelial lining is composed of biliary-type cuboidal
or nonciliated columnar cells and is surrounded by a
stroma that mimics ovarian stroma.
• The ovarian-like stroma is composed of bland spindle
cells, which typically stains with vimentin, actin, desmin,
estrogen, progesterone, and inhibin.
7.2.5 Clinical Issues
7.2.5.1 Presentation
• Most common signs/symptoms
– Asymptomatic
– Abdominal pain, palpable mass, distension, nausea,
vomiting, and occasionally, jaundice
7.2.5.2 Prognosis
• Patients with ovarian stroma exclusively in middle-aged
women have an indolent course with a good prognosis.
• In patients with complete surgical resection resulting in
only 5–10% rate of recurrence.
• Radical resection and noninvasive tumor type are inde-
pendent prognostic factors for the overall survival of
HBCA.
7.2.5.3 Treatment
• Radical excision is currently the best treatment for HBCA.
• Enucleation with free margins is an option and is indi-
cated where resection is impossible because of the size
and the anatomic location of the tumor and functional
liver reserve.
References
1. Seow J, McGill M, Wang W, Smith P, Goodwin M.Imaging hepatic
angiomyolipomas: key features and avoiding errors. Clin Radiol.
2020;75:88–99.
2. Naito K, Shigematsu Y, Fujiwara Y, Inamura K, Togashi Y, Inoue Y,
Takazawa Y, etal. Identication of a specic ultrasonographic nding for differentiating hepatic angiomyolipoma from hepatocellular
carcinoma. Clin Imaging. 2020;59:104–8.
3. Wang B, Ye Z, Chen Y, Zhao Q, Huang M, Chen F, Li Y, etal.
Hepatic angiomyolipomas: ultrasonic characteristics of 25 patients
from a single center. Ultrasound Med Biol. 2015;41:393–400.
4. Zhao Y, Ouyang H, Wang X, Ye F, Liang J.MRI manifestations
of liver epithelioid and nonepithelioid angiomyolipoma. J Magn
Reson Imaging. 2014;39:1502–8.
5. Klompenhouwer AJ, Dwarkasing RS, Doukas M, Pellegrino S,
Vilgrain V, Paradis V, Soubrane O, etal. Hepatic angiomyolipoma:
an international multicenter analysis on diagnosis, management
and outcome. HPB (Oxford). 2020;22:622–9.
7.2.4.2 Staging, Grading, andClassication
• HBCA could be subdivided into three noninvasive types
characterized by low-, medium-, and high-grade intraepithelial dysplasia.
Hepatic Parasitosis
FengMao, Yu-LiZhu, andYiDong
8
8.1 Terminology
Parasitic disease of liver (Hepatic parasitosis) is the disease
caused by the parasite in the liver. The liver is one of the
parasites most frequently involved in human organ. The liver’s common parasitic diseases are malaria, amebic liver
abscess, toxoplasmosis, kala-azar, schistosomiasis, bow rst
nematodes infection, echinococcosis, and so on.
8.1.1 Echinococcosis
• A zoonotic disease of parasite infection.
• Caused by tapeworm in larval stage: commonly E. granu-
losus (causes cystic echinococcosis, CE).
• Prevalent in cattle-raising regions worldwide with denitive hosts like dogs, cats, wolves, or other carnivores
excreting the eggs, and human as intermediate host
affected by fecal–oral route.
• Mostly affects liver (70%) and lungs (25%). Brain, kidney, and spleen are secondarily involved.
8.1.2 Amebiasis
– An endemic parasitic disease caused by protozoan
Entamoeba histolytica
– Usually causes colitis and liver abscess as a subacute
process
– Transmission between humans by the fecal–oral route
F. Mao · Y.-L. Zhu · Y. Dong (*)
Department of Ultrasound, Zhongshan Hospital, Fudan University,
Shanghai, China
e-mail: mao.feng@zs-hospital.sh.cn; zhu.yuli@zs-hospital.sh.cn;
dong.yi@zs-hospital.sh.cn
8.1.3 Schistosomiasis
– An trematodes caused infection: S. mansoni, S. hemato-
bium, and S. japonicum [1].
– Denitive host is the man and intermediate host are gen-
era of snails [1].
– Transmission by contacting with contaminated water that
contains living snails carrying cercaria (infective stage) of
Schistosomes [1].
– Due to the deposition of eggs in venules of the intestine
(S. japonicum and S. mansoni) causing liver brosis and
in venules of the ureters and urinary bladder (S. hemato-
bium) causing granulomatous inammation [1].
8.2 Imaging
8.2.1 Conventional Ultrasound Findings
8.2.1.1 Echinococcosis
• Types of CE may be found on liver ultrasound (US)
examination [2].
• Type CL (cystic lesion): Unilocular, uniform anechoic
content, not obviously delimited by a hyperechoic rim
(cyst wall not visible) (Fig.8.1a).
• Type CE1: Unilocular, uniform anechoic content, hydatid
sand, or snowake sign (exhibit ne echoes due to shifting of brood capsules) (Fig.8.1b).
• Type CE2: Multivesicular, multiseptated cysts (Fig.8.1c);
“wheel-like” structures produced by cysts septations, and
“rosette-like” or “honeycomb-like” structures indicated
the presence of daughter cysts (Fig.8.1d).
• Type CE3: Anechoic content, oating membrane, or as
“waterlily sign,” with dilated wavy membranes oating
on the top of remaining cyst uid) (Fig.8.1e, f).
• Type CE4: Heterogenous hypoechoic or hyperechoic
degenerative contents. No daughter cysts. May show a
“ball of wool” sign (Fig.8.1g–i).
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
W.-P. Wang et al. (eds.), Contrast-Enhanced Ultrasound Imaging of Hepatic Neoplasms,
https://doi.org/10.1007/978-981-16-1761-4_8
203
204
a
F. Mao et al.
• Type CE5: Characterized by thick calcied arch-shaped
wall. The calcication degree varies from partial to complete (Fig.8.1j).
• AE shows a “hailstorm” pattern on US, characterized by
multiple echogenic nodules and irregular margins [2].
8.2.1.2 Amebiasis
• Round or oval-shaped lesion.
• Lack of a prominent abscess wall.
• Hypo-echogenicity compared to normal.
• Fine low-level internal echoes (thick pus).
• Distal echogenicity enhancement.
• Contiguity with the diaphragm [3].
8.2.1.3 Schistosomiasis
• Ultrasonography may demonstrate periportal brosis
forming a characteristic “map-like,” “network-like,” or
“patches” pattern in liver parenchyma [1, 4, 5].
• Splenomegaly, the presence of collateral vessels and
expansive portal vein may also be observed [1, 4, 5].
• Doppler ultrasonography shows the blood ow may be
below 0.12m/s and examined in intrahepatic portal vein
[1, 4, 5].
8.2.2 Contrast Enhanced Ultrasound Findings
8.2.2.1 Echinococcosis
– No obvious enhancement was observed in neither arterial
phase, portal venous phase, or late phase (Fig.8.2).
– CEUS demonstrates perifocal inammatory reactions, as nod-
ular zones of peripheral ring enhancement are seen (Fig.8.3).
8.2.3 CT Findings
8.2.3.1 Echinococcosis
• CE on CT and US may display the same ndings. Cyst
uid demonstrates 3–30HU water attenuation. Cyst wall
calcication or internal septa is easily detected. A high-
b
c
Fig. 8.1 Features of cystic echinococcosis (CE) on B mode ultrasound.
Type cystic lesion (CL): Unilocular, with uniform anechoic content, not
clearly delimited by a hyperechoic rim (a). Type CE1: Unilocular, simple cyst with uniform anechoic content (b). Type CE2: Multivesicular,
multiseptated cysts (c); cysts septations produce “wheel-like” struc-
d
tures (d). Type CE3: Anechoic content with detachment of laminated
membrane from the cyst wall visible as oating membrane (e) or as
“waterlily sign” (f). Type CE4: Heterogenous hypoechoic (g), hyperechoic degenerative contents (h), and “ball of wool” sign (i). Type CE5:
Cysts with thick calcied wall (j)
e
8 Hepatic Parasitosis
205
f
g
i
h
j
Fig. 8.1 (continued)
206
a
e
F. Mao et al.
b
c
d
f
Fig. 8.2 A case of echinococcosis with calcication on B mode ultrasound and contrast enhanced ultrasound (CEUS). A hyperechoic focal
liver lesion was detected in the right lobe of liver (a). After injection of
contrast agents, the lesion showed non-enhancement during arterial
phase (b), portal venous phase (c), or late phase (d). The lesion was
conrmed by surgery and histopathological results (e). Multiple granulomas could be detected in the background of caseous necrosis in HE
stain (f)
a
8 Hepatic Parasitosis
207
attenuation wall at unenhanced CT even without calcication was typical of a hydatid cyst [6].
• AE is showed as an inltrating tumor-like hepatic mass
with heterogeneous contents, irregular margins, calcications, and hypoattenuating areas; these are characteristic
unenhanced CT ndings of alveolar echinococcosis. AE
was also found to be among the liver that manifests as diffuse lobar involvement [7].
• After an intravenous contrast medium, no substantial
enhancement is observed; however, in the delayed phase, the
broinammatory surrounding part may faintly enhance [7].
8.2.3.2 Amebiasis
• On CT scan, a rounded, low-density lesion, well dened,
homogeneous septated cavity, and considerable uid
were usually found in an amebic abscess [6].
• On enhanced CT, the margin presents a hypervascular
halo and a thick hypovascular halo [6].
8.2.3.3 Schistosomiasis
– Computed tomography ndings schistosomiasis of liver
are low-attenuation rings or bands in the central part of
the liver surrounding the large portal vein branches [4, 8].
– Markedly enhanced after contrast material administration
[4, 8].
– Other frequent ndings include liver cirrhosis, collateral
circulation, hepatosplenomegaly, gastroesophageal varix,
portal vein thrombosis, and ascites [4, 8].
8.2.4 MRI Findings
8.2.4.1 Echinococcosis
– CE shows a low-signal intensity rim on T2-weighted
MRI, which has been proposed as a characteristic sign of
hydatid disease. Collapsed parasitic membranes appear as
twisted linear structures within the cyst. MR imaging is
b
c
Fig. 8.3 A case of echinococcosis on B mode ultrasound and contrast
enhanced ultrasound (CEUS). A solid-cystic lesion could be detected in
the right lobe of liver (a). The lesion consisted of multiple cysts (b).
Color ow signals could be detected inside the lesion (c). Arterial
Doppler spectrum with high resistance index (RI) as 0.65 was measured
d
(d). After injection of ultrasound contrast agents, the lesion showed heterogeneous hyperenhancement during arterial phase (e, f, g), with multiple cystic non-enhanced regions. The lesion was iso-enhanced in the
portal venous phase (h) and hypoenhanced in the late phase (i). Gross
observations showed multiple cystic structures with uniform size (j)
208
fe
F. Mao et al.
hg
i
Fig. 8.3 (continued)
j
8 Hepatic Parasitosis
Fig. 8.3 (continued)
209
ji
superior in demonstrating irregularities of the rim, which
represent incipient detachment of the membranes [9].
– The MR ndings of AE in the liver are multiple small
rounded cysts with a weakly enhanced solid component,
and such lesions are depicted clearly at T2-weighted
MRI [10].
– Same as contrast enhanced CT, no substantial enhance-
ment is observed after injection.
8.2.4.2 Amebiasis
• The hepatic abscess cavity is lled with thick necrotic
material. MRI discloses a homogenous hypointense signal on the T1WI and hyperintense on the T2WI with
clearly dened margins, heterogeneous in some, due to
uidity and debris of the necrotic exudate [11].
• The abscess wall and border of the adjacent liver tissue
may show a hypointense annular ring on T1WI and hyperintense on T2WI [11].
8.2.4.3 Schistosomiasis
• On MRI, brous tissue along the portal vein and its
branches are hypo- or iso-intense on T1WI and hyperintense on T2WI [4, 9].
• After injection of contrast material, the periportal brous
tissue is enhanced markedly [4, 8].
8.2.5 Other Imaging Findings
8.2.5.1 Echinococcosis
– Positron Emission Tomography (PET) demonstrates met-
abolic activity and so can effectively determine the biological boundary of liver AE, recommended for the initial
assessment and follow-up of AE(6).
8.2.6 Best Imaging Protocol Advices
8.2.6.1 Echinococcosis
• US can play as a basic tool for diagnosis and classication
of CE in abdominal locations [12].
• Conventional radiography is useful to diagnose thoracic
and bone involvement [12].
• CT or MRI with a T2WI sequence, if possible cholangiopancreatography (MRCP) are indicated in [12]:
– Subdiaphragmatic lesion
– Disseminated lesion
– Extra-abdominal lesion.
– Complicated cysts (abscess, cysto-biliary stulae)
– Preoperative evaluation
• Whenever possible, MRI should be preferred to CT due to
better visualization of liquid areas within the lesion [12].