Liver pathology

Steatosis

This is the build-up of triglycerides in the liver.
Generally a lifestyle related condition such as excessive alcohol consumption but may have metabolic/viral causes.
If there are non alcohol related causes, this is now MASLD (Metabolic dysfunction-associated steatotic liver disease ). It was previously termed Non Alcoholic Fatty Liver Disease (NAFLD).
This may progress to MASH (metabolic dysfunction-associated steatohepatitis). previously called NASH (ie Non-Alcoholic Steato-Hepatitis), which is a known precursor to scarring, fibrosis and cirrhosis.

REF: Rinella ME, Sookoian S. From NAFLD to MASLD: updated naming and diagnosis criteria for fatty liver disease. J Lipid Res. 2024 Jan;65(1):100485. doi: 10.1016/j.jlr.2023.100485. Epub 2023 Dec 14. PMID: 38103785; PMCID: PMC10824973.

Steatosis is charcterised on ultrasound with increased attenuation and a may have a coarse texture.

The accumulation of iron in patients with haemachromatosis can have the same high attenuation appearance on ultrasound.
Due to the ‘watershed’ of the liver it is common to get areas of fatty sparing. Conversely you occasionally may have focal fatty infiltration.

Ultrasound image longitudinal to the liver demonstrating grade 1 steatosis. The echogenicity is increased relative to the kidney with mild hepatomegaly. Both the diaphragm and vessel walls are clearly seen. Note the general settings.

Ultrasound image transverse to the liver demonstrating grade 1 steatosis. The hepatic vein walls and diaphragm are clearly seen.

Ultrasound image of grade 2 steatosis longitudinal to the liver.
The liver becomes more attenuative resulting in impaired visualisation of the portal vein and diaphragm. Hepatomegaly is often observed.

Ultrasound image of grade 2 steatosis transverse to the liver. Note the impaired visualisation of the portal vein wall and diaphragm.

Ultrasound image of grade 3 steatosis longitudinal to the liver. This grade is characterised by high attenuation with poor to no visualisation of the portal vein wall, posterior parenchyma and diaphragm.

Ultrasound image of grade 3 steatosis transverse to the liver. Note the poor visualisation of the posterior liver and diaphragm despite low frequency penetration settings.

Ultrasound image of focal fatty sparing within the liver adjacent to the gallbladder wall.

Most commonly see adjacent to the porta hepatis or gallbladder wall. Appearances can be well or poorly defined, ovoid or irregular in shape.

Ultrasound image of focal fatty sparing adjacent to the porta hepatis. An example of a poorly defined irregular area of sparing.

Ultrasound image of NASH cirrhosis longitudinal to the liver.

Note the diffuse increase in echogenicity and attenuation despite penetration settings. The parenchyma is diffusely heterogenous and contour lobulations are also observed.

Ultrasound image of NASH cirrhosis transverse to the liver.

Ultrasound image of regenerative nodules in NASH cirrhosis.

Ultrasound image of NASH cirrhosis demonstrating the nodularity of the liver contour.

Cirrhosis

According to The World Health Organization (Anthony P.P. et al. J.Clin.Pathol. 31:395,1978) there are

3 morphologic classifications

Macronodular
Micronodular
Mixed

5 Histological classifications:

Portal
Post-necrotic
Post Hepatitic
Biliary
Congestive

Caused by the following 6 aetologic agents:

Genetic
Toxic
Infectious
Biliary
Vascular
Cryptogenic

Ultrasound image longitudinal to the liver. This demonstrates the diffuse coarsened and mildly heterogenous texture in micronodular cirrhosis.

Ultrasound image longitudinal to the liver demonstrating an enlarged caudate lobe in alcohol related micronodular cirrhosis.

This is likely due to redistribution of blood flow between segments in progressed disease.

Ultrasound image longitudinal to the liver demonstrating a diffusely coarsened and heterogenous texture in mixed nodular cirrhosis (ETOH and Hep C).

Ultrasound image of mixed nodular cirrhosis. Using a high-frequency linear probe, the diffuse heterogenous changes are more clearly observed.

Ultrasound image longitudinal to the liver. This demonstrates hepatitis C related macronodular cirrhosis. Note the diffuse coarse and nodular texture.

Ultrasound image of macronodular cirrhosis. This image demonstrates multiple regenerative nodules that account for the diffuse nodular change in a cirrhotic liver.

Careful examination must be undertaken when these exceed 10mm in size, as underlying neoplasia cannot be excluded.

Macronodular Cirrhosis ultrasound image- Larger nodules , may be scarred. It is irregularly distributed throughout the liver usually due to an infectious agent such as viral hepatitis. It does not spread uniformly throughout the liver. Ascites is seen which is not uncommon in these advanced cases.

Ultrasound image- Advanced Cirrhosis

Ultrasound image. Micronodular Cirrhosis- Small and uniform nodules usually due to a chemical agent as alcohol which is diffuse and uniform throughout the liver.

Ultrasound image. Note the nodular borders of the liver in advanced cirrhosis. A Normal liver has a smooth capsule.

Varices

Colour Doppler image of small gastric varices.

Dual screen ultrasound image of large gastric varices.

Longitudinal ultrasound image of oesophageal varices at the diaphragm. In the majority of cirrhotics, the left gastric vein is afferent to oesophageal varices, which together form gastroesophageal varices. These bypass the hepatic circulation commonly via the azygous vein and SVC.

B-mode and colour Doppler ultrasound image of a large left gastric varix draining to oesophageal varices seen in the left adjacent image.

B-mode and colour Doppler image longitudinal to the spleen demonstrating multiple large varices at the hilum.

Colour Doppler image of varices draining from the splenic vein to the left renal vein, forming a splenorenal shunt.

B-mode and colour Doppler image longitudinal to the liver demonstrating a recannalised umbilical vein.

A transhepatic shunt, this drains to the inferior epigastric vessels and external iliac vein.

Colour Doppler image longitudinal to the liver demonstrating a recannalised umbilical vein within the falciform ligament. Note the large amount of surrounding ascites.

B-mode and colour Doppler image of a recannalised umbilical vein tracking deep to the abdomen wall to the umbilicus.

Transverse dual screen image of a recannalised umbilical vein deep to the abdomen wall adjacent to the umbilicus.

B-mode image of a portal cavernoma.

A complex of varices that form in response to extrahepatic portal venous obstruction (e.g. thrombosis). These are seen in the periportal region and are constituted by the paracholedochal and epicholedochal venous plexus. They redirect flow to the intrahepatic portal vein branches, bypassing the occluded portal vein.

Colour Doppler image of a portal cavernoma at the porta hepatis.

These varices may extend to involve the portal vein branches, pancreas, gallbladder and duodenum.

Colour Doppler image of ectopic varices within the gallbladder wall in a portal cavernoma case.

B-mode and colour Doppler image of ectopic varices within the pancreatic head in a portal cavernoma case.

Colour Doppler image of hepatofugal portal venous flow in a decompensated cirrhotic liver.

Liver Cysts

Simple Cysts are common and generally of no clinical significance.
Complex or very numerous cysts may be related to other medical conditions and require follow up and/or further investigation.

Ultrasound kidneys and spleen for multicystic disease.

Ultrasound of large, simple cyst in the right lobe of the liver and several smaller cysts.
Use colour to differentiate vascular pathways.

Hydatid Cysts

Hydatid Cysts are the infestation of a specific parasitic tapeworm.
They are transmitted via ingestion of eggs which can infiltrate any organ but liver and lung are most common.
Consumption of poorly cooked offal is a primary source.
They often are sub-clinical, thus gaining time to calcify.

Ultrasound image- Poorly circumbscribed, calcified cysts consistent with calcified Hydatid cysts

Ultrasound image- May mimic a granuloma

Haemangioma

The most common benign solid mass in the liver.
When small are uniformly echogenic but if >2cm may develop cavernous centres (Cavernous Haemangioma)
May be solitary or multiple.
Depending on size or number the differential diagnoses are:

Focal Nodular Hyperplasia (FNH)
Metastases
Hepatocellular Carcinoma (HCC)

When large, a hamangioma will degenerate into a ‘Cavernous Haemangioma’ and will be indistiguishable on ultrasound from a HCC.

Ultrasound image- Haemangiomata are typically echogenic.

Commonly with higher resolution ultrasound equipment, a hemangioma will have a mottled appearance. Again, this cannot be relied on for definitive diagnosis. So, if the lesion is identified for the first time, it should be followed-up.

Focal Nodular Hyperplasia (FNH)

FNH is the second most common solid tumor of the liver, surpassed in prevalence only by hepatic hemangioma.

In cases of FNH ultrasound findings are variable. The lesion may appear as a homogeneous mass that is isoechoic, hypoechoic, or hyperechoic. FNH has a mass effect that may displace intrahepatic blood vessels. In only 18% of cases is a central scar (hypoechoic centre) present.They look very similar to a liver haemangioma.

They are related to an area of vascular malformation. It is more common in women than men.

They are generally less than 5cm. Contrast can help define the lesion.

Dual screen B-mode image of a subtle isoechoic focal nodular hyperplasia.

Colour Doppler dual screen image of focal nodular hyperplasia. This image demonstrates the spokes wheel configuration vascular pattern.

Ultrasound image of focal nodular hyperplasia in a fatty liver. Note the central scar and hypoechoic features.

Ultrasound image of multiple focal nodular hyperplasia in a fatty liver.

B-mode and Colour Doppler image of focal nodular hyperplasia demonstrating an isoechoic lesion with contour lobulations and a central feeding artery.

Diagnosis and management of hepatic focal nodular hyperplasia.

Liver Metastases

Almost pathognomonic is this target-lesion appearance of increased echogenicity with a hypoechoic rind .
Metastases may range from hypoechoic to echogenic similar to haemagiomas.
Any case of multiple liver lesions requires further investigation according to the clinical context.

Ultrasound image- Metastases are typically a “target” appearance.

Ultrasound image- Multiple metastatic lesions abutting one another.

Ultrasound image- Liver metastatic lesion

The same patient. Colour doppler cannot be used to classify the lesion.

Ultrasound image of metastatic bowel cancer presenting as hyperechoic target lesions.

Ultrasound image of metastatic neuroendocrine cancer presenting as solid hypoechoic lesions in a fatty liver.

Ultrasound image of metastatic pancreatic cancer presenting as multiple solid hypoechoic lesions in a fatty liver.

B-mode and colour Doppler image of a large metastatic neuroendocrine carcinoma (prostatic origin), presenting as heterogenous and vascular mass containing cystic spaces.

Ultrasound image of a large metastatic small cell carcinoma presenting as a well-defined isoechoic mass occupying most of the right liver lobe.

Ultrasound image of a large metastatic non-epithelioid mesothelioma presenting as an ill-defined isoechoic heterogenous mass occupying most of the right liver lobe.

Ultrasound image of metastatic adenocarcinoma of the bowel presenting as an infiltrating ill-defined hypoechoic mass.

Ultrasound image of metastatic transitional cell carcinoma presenting as an infiltrating ill-defined hypoechoic mass.

Hepatocellular Carcinoma

The biggest risk factors are chronic hepatitis or cirrhosis.
As such, it’s incidence is remarkably higher in countries with high rates of hepatitis’, than in other countries.

Hepatocellular Cancer ultrasound image.

A technically difficult scan however the complicated area of heterogeneity within the liver is visible. Further investigation would be required as with all liver masses.

Ultrasound image- The appearances can be variable. The smaller the lesion the more difficult it is to distinguish between a benign lesion such as a haemangioma and a hepatocellular carcinoma. As thay increase in size they become heterogeneous.

Look for invasion into the vessels ie IVC,hepatic veins and portal.

Ultrasound image of a large ill-defined infiltrative HCC.

Ultrasound image of the regional (peripancreatic) metastasis in aggressive HCC.

Ultrasound image of a large well-defined HCC.

Colour Doppler image of a large well-defined HCC.

Ultrasound image of an ill-defined rounded HCC containing calcification.

B-mode and Colour Doppler image of an ill-defined rounded HCC containing calcification.

Ultrasound image of a small ill-defined HCC.

B-mode and Colour Doppler image of a well-circumscribed HCC.

Liver Trauma - Contusion and Haematoma

Blunt injury liver trauma was graded in 2005. http://pubs.rsna.org/doi/abs/10.1148/rg.251045079

Ultrasound image of a central liver contusion resulting from a motor vehicle accident deceleration seatbelt injury.

Liver Abscess

The pyogenic abscesses on the image below were diagnosed following a fine needle aspiration.
A 3 month follow up after treatment with intravenous antibiotics showed complete resolution.

The clinical presentation and absence of internal vascularity assist with the diagnosis of lesions such as these. Caution is always required that a mass is not mistaken for an abscess.

Liver abscess ultrasound image.

Hepatic Adenoma

Are more common in women using contraceptives due to their hormonal motivation. However obesity, diabetes and steroid use are also risk factors.
Hepatic adenomas may haemaorrhage so it is important to diagnose.
Are larger than FNH. They may contain fat and calcification with surrounding fatty sparing.
Hepatic adenomas on ultrasound vary in echogenicity from hypoechoic to hyperechoic. Usually heterogeneous.
Usually solitary.

Hepatocellular adenoma: when and how to treat? Update of current evidence 2016.

Liver Lipoma

Liver Lipomas are extremely rare (Ref 2). There is an association with renal angiomyolipomas and tuberous sclerosis.

The diagnosis is based on finding an echogenic mass. They are usually less echogenic than a small haemangioma.

Differential diagnoses:

Metastasis
Haemangioma
Angiomyolipoma

As such, ultrasound alone cannot confirm the diagnosis.

Contrast ultrasound CT and MRI can assist with distinguishing the alternatives.

Angiomyolipoma

These lesions are hyperechoic, just as they are in the kidney where they are more common.

They look similar to a lipoma on ultrasound and CT or MRI are the most accurate modalities to confirm the diagnosis.

Angiomyolipoma of the Liver: A Rare Benign Tumor.

Know Your Machine

When investigating any liver lesion in technically difficult patients, it is important to have a thorough understanding of how to optimise your image and not be reliant on the factory preset.

The example below is of a large, yet subtle mass adjacent to the diaphragm in an obese patient.

Through good manipulation of the settings, the sonographer has better demonstrated the complex solid nature of the mass and proven it to have internal vascularity.

In particular, decrease the frequency for a large patient, position the focal zone over the region of interest and optimise the colour Doppler ultrasound settings to include slow flow.

Ultrasound of a liver mass. Demonstrating the importance of optimising the image to better show a subtle mass.

Portal Vein Thrombosis

Ultrasound image with colour Doppler – A case of non-occlusive portal vein thrombosis extending from the portosplenic confluence to the right portal vein branch in a cirrhotic patient.