Diagnostic Ultrasound - Abdomen and Pelvis

Echogenic Liver Mass
880
Differential Diagnoses: Liver
DIFFERENTIAL DIAGNOSIS
Common
• Focal Steatosis
• Hepatic Cavernous Hemangioma
• Hepatic Metastases
• Pyogenic Hepatic Abscess
• Normal Anatomic Pitfalls
○ Hepatic Ligaments and Fissures
○ Diaphragmatic Leaflets
○ Refractile Artifact
• Hepatocellular Carcinoma (HCC)
Less Common
• Cholangiocarcinoma (Intrahepatic)
• Hepatic Adenoma
• Fibrolamellar Carcinoma
• Amebic Hepatic Abscess
• Hepatic Angiomyolipoma (AML)
• Biliary Hamartoma
• Hepatic Hydatid/Echinococcus Cyst
• Hepatic Epithelioid Hemangioendothelioma (HEHE)
• Hepatic Lipoma
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
• Is echogenic lesion mass or echogenic focus?
○ Mass: Usually spherical
○ Echogenic focus: Often linear, such as surgical device,
pneumobilia, portal vein gas, etc.
• Significant overlap in appearance of many echogenic
masses
○ Contrast-enhanced triphasic CT or MR may be needed
for further characterization
Helpful Clues for Common Diagnoses
• Focal Steatosis
○ No mass effect, with vessels running undisplaced
through lesion
○ Varied appearances
– Hyperechoic nodule/confluent hyperechoic lesions
□ May simulate metastases
– Fan-shaped lobar/segmental distribution
○ CT or MR are good problem-solving tools
• Hepatic Cavernous Hemangioma
○ Typically homogeneously hyperechoic
– Probably due to slow blood flow rather than multiple
interfaces
– Smooth or lobulated well-defined borders
– May have acoustic enhancement
○ Echogenicity may vary
– Echogenicity may change over time during imaging
– Direction and angle of insonation may alter echogenic
appearance
– May appear hypoechoic in underlying fatty liver
– Large lesions more heterogeneous
• Hepatic Metastases
○ Hyperechoic metastases: Most commonly from GI tract
○ Vascular metastases
– Neuroendocrine tumors, melanoma, choriocarcinoma,
renal cell carcinoma
○ Target or bull's-eye appearance
– Iso- or hyperechoic metastatic nodule with hypoechoic
rim or halo
– Usually from aggressive primary tumors
– Bronchogenic carcinoma: Classic example
○ Calcified metastasis
– Markedly echogenic interface with acoustic
shadowing or diffuse small echogenic foci
– Mucinous primary: Colon, ovary, breast
– Calcific/ossific primary: Osteosarcoma,
chondrosarcoma, neuroblastoma, malignant teratoma
– Treated metastasis
• Pyogenic Hepatic Abscess
○ Echogenicity of abscess
– Anechoic (50%), hyperechoic (25%), hypoechoic (25%)
– Early lesions tend to be echogenic and poorly
demarcated
– May evolve into well-defined, nearly anechoic lesions
○ "Cluster" sign
– Cluster of small pyogenic abscesses coalesce into
single large cavity
○ Fluid level or debris, internal septa
○ Abscess wall: Hypoechoic or mildly echogenic
○ Gas within abscess: Bright echogenic foci with posterior
reverberation artifact
• Normal Anatomic Pitfalls
○ Hepatic Ligaments & Fissures, Diaphragmatic Leaflets
– Infolding of fat along these normal structures creates
echogenic focus near surface of liver
– In short axis section, "lesions" can appear spherical and
resemble masses
– Turn US beam perpendicular to show linear shape of
"lesion"
○ Refractile Artifact
– Lateral edge shadows at junction of vessels or
gallbladder neck
• Hepatocellular Carcinoma (HCC)
○ Hyperechoic appearance indicates fatty metamorphosis/
hypervascularity
– Simulates hemangioma or focal steatosis
□ Look for background cirrhotic liver, portal vein
thrombosis, risk factors (hep B, C, alcohol)
□ Generally irregular intratumoral vascularity
○ Small lesions more likely to be hyperechoic
Helpful Clues for Less Common Diagnoses
• Cholangiocarcinoma (Intrahepatic)
○ Heterogeneous mass with ill-defined margin and satellite
nodules
– Mostly hyperechoic (75%); iso-/hypoechoic (14%)
○ Isolated intrahepatic ductal dilatation upstream to mass
without extrahepatic duct dilatation
• Hepatic Adenoma
○ Young woman with oral contraceptive use
○ Heterogeneous and hypervascular mass with
hemorrhage
○ Complex hyper-/hypoechoic mass with anechoic areas
– Due to fat, hemorrhage, necrosis or calcification
○ Well-defined border, round or lobulated