K

Liver Pathology - Vocabulary Flashcards

Diffuse Disease

  • The hepatocyte is a parenchymal liver cell that performs all liver functions. Diffuse hepatocellular disease affects hepatocytes and interferes with liver function. Measured by hepatic enzyme levels, which are elevated with cell necrosis.
  • Major diffuse disease types include:
    • Fatty liver infiltration
    • Hepatitis (acute and chronic)
    • Cirrhosis (acute and chronic)

Fatty Infiltration

  • Also called fatty liver or steatosis; defined as an acquired, reversible disorder of metabolism resulting in accumulation of triglycerides within hepatocytes.
  • Fatty infiltration implies increased lipid accumulation in hepatocytes and is the result of major liver injury or a systemic disorder leading to impaired or excessive fat metabolism.
  • Causes of fatty liver include:
    • Obesity
    • Excessive alcohol intake
    • Poorly controlled hyperlipidemia
    • Diabetes
    • Excess corticosteroids
    • Pregnancy
    • Total parenteral nutrition (TPN)
    • Severe hepatitis
    • Glycogen storage disease (genetic disorder)
    • Cystic fibrosis
    • Pharmaceutical agents
  • Focal fatty infiltration and focal fatty sparing:
    • Focal regions of normal liver within areas of fatty infiltration (focal fatty infiltration)
    • Focal fatty sparing commonly occurs adjacent to the gallbladder, porta hepatis, caudate lobe, and liver margins.

Hepatitis

  • Hepatitis is the general name for inflammatory and infectious disease of the liver. Can be viral, bacterial, fungal, or parasitic.
  • Causes may include local infection (e.g., viral hepatitis), infection elsewhere in the body (e.g., infectious mononucleosis, amebiasis), or chemical/drug toxicity.
  • Inflammation can range from mild (impaired hepatocyte function) to severe necrosis with obstruction of blood and bile flow and impaired liver function.
  • May cause elevation of diagnostic labs: ALT, \, AST, \, conjugated and unconjugated bilirubin.

Viral Hepatitis

  • Hepatitis A, B, and C are the more common hepatotropic viruses: HAV, HBV, HCV.
  • HAV: found worldwide, spread primarily by fecal contamination; endemic in developing countries; acute infection with potential complete recovery or death from acute liver failure.
  • HBV: exists in the bloodstream and body fluids; transmission via transfusions, contaminated needles, sexual contact; highest risk to healthcare workers.
  • HCV: diagnosed by the presence of anti-HCV antibodies in blood; transmitted via blood/body fluids; often through sharing needles or sexual contact.
  • In the United States, approximately 60 ext{ extperthousand} of acute viral hepatitis is type B, 20 ext{ extperthousand} type A, and 20 ext{ extperthousand} other types.
  • Initial symptoms for acute and chronic hepatitis may include flu-like and GI symptoms: loss of appetite, nausea, vomiting, fatigue.
  • Viral hepatitis may be fatal due to secondary acute hepatic necrosis or progression to chronic hepatitis with portal hypertension, cirrhosis, and hepatocellular carcinoma (HCC).

Acute Hepatitis

  • Without complications, clinical recovery from acute hepatitis usually occurs within 4 ext{ months}.
  • Complications range from mild disease to massive necrosis and liver failure.
  • Pathologic changes include:
    • Liver cell injury, swelling, and hepatocyte degeneration leading to necrosis
    • Reticuloendothelial and lymphocytic response with Kupffer cell enlargement
    • Regeneration

Acute Hepatitis: Ultrasound Features

  • Liver texture may be normal or portal vein borders may appear more prominent.
  • May show a “Starry Night” liver appearance (Van Gogh).
  • Liver parenchyma is slightly more echogenic than normal.
  • Attenuation may be present.
  • Hepatosplenomegaly may be present.
  • Gallbladder wall thickening may be seen.

Chronic Hepatitis

  • Exists when clinical or biochemical evidence of hepatic inflammation extends beyond 6 ext{ months}.
  • Causes include viral, metabolic, autoimmune, or drug-induced.
  • In chronic active hepatitis, changes are more extensive: inflammation across the limiting plate with perilobular spread, piecemeal necrosis, and fibrosis.
  • Symptoms may include nausea, anorexia, weight loss, tremors, jaundice, dark urine, fatigue, and varicosities.
  • Chronic persistent hepatitis is benign and self-limiting.
  • Chronic active hepatitis commonly progresses to cirrhosis and liver failure.

Chronic Hepatitis: Ultrasound Features

  • Liver parenchyma is coarse with decreased brightness of the portal triads.
  • Degree of attenuation is not as great as in fatty infiltration.
  • Liver does not typically enlarge with chronic hepatitis.
  • Fibrosis may produce soft posterior shadowing.

Cirrhosis

  • Definition: chronic degenerative disease of the liver with lobules infiltrated by fibrous tissue; parenchymal degeneration and fat infiltration; essential feature is simultaneous parenchymal necrosis, regeneration, and diffuse fibrosis, leading to disorganization of lobular architecture.
  • Major causes:
    • Hepatitis C (most common)
    • Alcoholic liver disease
    • NAFLD (non-alcoholic fatty liver disease)
    • NASH (non-alcoholic steatohepatitis)
    • Hepatitis B
    • Other causes: hemochromatosis (iron deposition), Wilson disease (copper deposition)
  • Types by nodularity:
    • Micronodular cirrhosis (most commonly due to chronic alcohol abuse)
    • Macronodular cirrhosis (caused by chronic viral hepatitis or other infections)
  • Clinical picture:
    • Acute cirrhosis can be asymptomatic or present with nausea, flatulence, ascites, pale stools, weakness, abdominal pain, varicosities, and spider angiomas; classic signs include hepatomegaly, jaundice, and ascites.
    • Chronic cirrhosis presents with nausea, anorexia, weight loss, jaundice, dark urine, fatigue, or varicosities and may progress to liver failure and portal hypertension.

Cirrhosis: Ultrasound Progression

  • Early phase: hepatomegaly with increased echogenicity and coarse texture; possible vascular changes (loss of triphasic hepatic waveform; altered hepatic artery waveform).
  • Mid phase: coarse echotexture, nodular borders, lobe atrophy, ascites.
  • Late phase: coarse echotexture, hyperechoic, small liver, nodular borders, possible nodules (risk of cancer), ascites, portal hypertension.
  • Diffuse liver disease progression examples include cirrhotic liver with ascites, shrunken liver, and thick gallbladder wall in late stages.

Glycogen Storage Disease

  • Six categories of glycogen storage disease based on clinical symptoms and enzymatic defects; type I (von Gierke disease) is most common.
  • Characterized by excess glycogen storage in liver and kidneys; inherited disease with abnormal storage/accumulation of glycogen in liver and kidneys.
  • Imaging findings (von Gierke example): hepatomegaly, increased echogenicity, round, homogeneous adenomas; large adenomas may be inhomogeneous.

Glycogen Storage Disease: Imaging Examples

  • A (von Gierke): hepatic adenoma in caudate lobe.
  • B: hepatic adenoma in right lobe.
  • Sonographically: hepatomegaly, increased echogenicity, round, homogeneous adenomas; larger adenomas may be inhomogeneous.

Hemochromatosis

  • Rare disease of iron metabolism with excess iron deposits throughout the body.
  • Can lead to cirrhosis and portal hypertension.
  • Sonographic findings: hepatomegaly, cirrhotic changes; increased echogenicity may be uniform across hepatic parenchyma.

Diffuse Abnormalities of the Liver Parenchyma

  • Biliary obstruction, common duct stones and strictures, extrahepatic mass, and passive hepatic congestion are diffuse parenchymal abnormalities.

Biliary Obstruction

  • Proximal to the cystic duct (obstruction upstream):
    • Causes: gallstones, carcinoma of the common bile duct, metastatic invasion of porta hepatis.
    • Clinical: jaundice and pruritus.
    • Labs: elevated direct bilirubin and alkaline phosphatase (ALP).
  • Distal to the cystic duct (obstruction downstream):
    • Causes: stones in the common duct, extrahepatic mass in porta hepatis, common duct stricture.
    • Clinical: RUQ pain, jaundice, pruritus.
    • Labs: elevated direct bilirubin and ALP.
  • Distal obstruction distal to a cystic duct may be caused by stones in the CBD near the distal end; imaging may show a dilated common duct.
  • Extrahepatic mass near porta hepatis can mimic biliary obstruction and presents with similar signs.
  • Passive hepatic congestion arises from congestive heart failure and presents with hepatomegaly; liver tests may be normal to slightly elevated.

Focal Hepatic Disease

  • Focal lesions may be congenital or acquired; can be solitary or multiple; patients often asymptomatic.
  • If found in patients younger than 50, evaluate for polycystic kidney disease (ADPKD).
  • Simple hepatic cysts: well-demarcated, thin-walled, anechoic with posterior acoustic enhancement; usually asymptomatic.
  • Polycystic liver disease: autosomal dominant; occurs with polycystic kidney disease; hepatic cysts are usually small (<2–3 cm), multiple, and can enlarge to cause biliary obstruction at porta hepatis.

Focal Inflammatory Disease of the Liver

  • Hepatic abscesses can be intrahepatic, subhepatic, or subphrenic; fever, leukocytosis, right upper quadrant pain.
  • Sonographic search for solitary or multiple lesions; look for abnormal fluid collections in Morison’s pouch, subdiaphragmatic, or subphrenic spaces.

Pyogenic (Bacterial) Abscess

  • Pyogenic abscesses account for about 80 ext{ extperthousand} of hepatic abscesses.
  • Routes for bacterial entry include biliary tract disease (most common), portal vein, hepatic artery, direct extension from contiguous infection, or trauma.
  • Common infection sources include cholangitis; portal pyemia from appendicitis, diverticulitis, inflammatory bowel disease; trauma.

Amebic Abscess

  • Caused by Entamoeba histolytica; liver abscesses form from trophozoites via portal venous system.
  • Amebiasis is contracted by ingesting cysts in contaminated water/food; organism typically affects colon and cecum; possible spread to liver via portal vein.
  • Clinically may be asymptomatic or present with GI symptoms, abdominal pain, diarrhea, leukocytosis, low-grade fever.
  • Gross pathology: cavitary lesion filled with yellow necrotic material (not pus).

Echinococcal Cyst (Hydatid Disease)

  • Caused by Echinococcus tapeworm; humans are intermediate hosts; dog is the definitive host.
  • Larvae reach the liver via the portal circulation.
  • Imaging may show daughter cysts and signs such as the inner membrane producing a water-lily sign (floating membranes) within the cyst.

Fungal Abscess (Candidiasis)

  • In immunocompromised hosts (chemotherapy, transplant recipients, HIV).
  • Sonographic hallmarks include a wheel-within-a-wheel or bull’s-eye appearance; uniformly hypoechoic focus with echogenic foci.

Pneumocystis Carinii

  • Common opportunistic infection in AIDS patients and other immunocompromised states (transplant recipients, chemotherapy).
  • Sonographic pattern ranges from diffuse tiny non-shadowing echogenic foci to extensive parenchymal replacement by echogenic clumps of calcification.

Chronic Granulomatous Disease

  • Congenital defect in phagocyte killing; predisposes to severe infections.
  • Sonographic findings include poorly marginated hypoechoic mass with posterior enhancement; calcifications may be present with posterior shadowing; aspiration may be needed for diagnosis.

Benign Hepatic Tumors

Cavernous Hemangioma

  • Most common benign liver tumor; usually found in women; patients often asymptomatic; rare bleeding may cause RUQ pain.
  • Sonographically: irregular, echogenic mass due to vascular components; benign appearance.

Liver Cell Adenoma

  • More common in women; linked to oral contraceptive use.
  • Symptoms can include RUQ pain from rupture with intratumoral bleeding.
  • Higher incidence in patients with type I glycogen storage disease or von Gierke disease.
  • Surgical resection is recommended due to risk of malignant transformation.

Liver Lipoma

  • Mentioned in imaging context as an example of an artifact-related finding; not a major lesion type but relevant to ultrasound interpretation.

Focal Nodular Hyperplasia (FNH)

  • Second most common benign liver mass after hemangioma; seen mainly in women under 40.
  • Thought to arise from developmental hyperplastic changes related to congenital vascular formation.
  • Usually asymptomatic; tends to occur in the right lobe.
  • Typical features include a well-circumscribed lesion, often subcapsular or pedunculated, with a central fibrous scar; composed of normal hepatocytes, Kupffer cells, bile ducts, and fibrous tissue; multiple nodules may be separated by fibrous bands.
  • Increased bleeding risk within tumors can occur in some patients.

Hepatocellular Carcinoma (HCC)

  • The most common primary malignant neoplasm of the liver; often arises in the setting of cirrhosis or chronic hepatitis B/C; more common in men.
  • Pathogenesis related to cirrhosis (about 80 ext{ extperthousand} of HCC arises in cirrhosis), chronic HBV infection, and dietary hepatocarcinogens.
  • Presentation patterns:
    • Solitary massive tumor
    • Multiple nodules throughout the liver
    • Diffuse infiltrative masses
  • Tumor can be focal or invasive with necrosis and hemorrhage; poorly defined lesions possible.
  • Can be very invasive and may invade hepatic veins, potentially causing Budd-Chiari syndrome; portal venous system can also be invaded.
  • Often associated with cirrhosis or hepatitis B/C history; imaging and pathology reflect aggressive behavior.

Metastatic Disease

  • Most common form of liver neoplastic involvement.
  • Primary sites commonly include colon, breast, and lung.
  • Prognosis varies by primary site; shorter survival after detection for hepatocellular carcinoma and pancreatic, stomach, and esophageal primaries; longer survival for head and neck cancers and colon cancer.
  • Sonographic appearance varies: multiple well-defined iso- to hyperechoic or hypoechoic nodules throughout the liver; metastases may show central necrosis with indentation.

Other Malignant and Benign Liver Lesions

Hepatoblastoma

  • Most common malignant liver tumor in infants and young children, usually prior to age 2.
  • Presents as enlarged, asymptomatic abdominal mass; associated with Beckwith-Wiedemann syndrome and familial adenomatous polyposis; elevated alpha-fetoprotein (AFP).
  • May metastasize to lungs and invade portal vein.

Infantile Hepatic Hemangiomas (Infantile Hemangioendothelioma)

  • Benign vascular tumors in neonates/infants; rapid growth in early months; ultrasound shows hepatomegaly with high vascularity on color Doppler; can cause congestive heart failure; often spontaneously regress by 12–18 months.

Lymphoma (Hepatic Involvement)

  • Malignant neoplasm of lymphocytes; may cause hepatomegaly with normal or diffusely altered parenchymal echoes.
  • Focal hypoechoic masses may be seen; symptoms include enlarged, non-tender lymph nodes, fever, fatigue, night sweats, weight loss; splenomegaly or retroperitoneal nodes support diagnosis.

Elastography

  • Measures tissue stiffness; malignant lesions tend to be stiffer than benign ones.
  • Overall parenchyma stiffness reflects fibrosis from chronic disease (e.g., hepatitis) and cirrhosis.
  • Useful to identify patients with little fibrosis or to assess severe fibrosis/cirrhosis.

Additional Topics

Liver Biopsy with Ultrasound

  • There are ultrasound-guided biopsy techniques used clinically, as referenced by supplementary material links (not detailed in transcript).

Hepatic Trauma

  • The liver is the third most commonly injured abdominal organ after the spleen and kidney.
  • Liver laceration occurs in about 3\% of trauma patients and is often associated with other injuries.
  • Management depends on laceration size, amount of hemoperitoneum, and patient status.
  • The right lobe is more commonly affected than the left.
  • Trauma severity ranges from small lacerations to large lacerations with hematoma, subcapsular hematoma, or capsular disruption.

Additional Conditions Mentioned

  • Schistosomiasis: parasite lifecycle can involve skin entry and migration to the liver; can lead to portal hypertension; differential includes portal hypertension or thrombus and Budd-Chiari syndrome.
  • Hydatid disease (echinococcal cysts): inner membranes may create water-lily sign; cysts can be complex with daughter cysts.
  • Schistosomiasis and other systemic infections may present with hepatic involvement and portal changes.

Notes on Specific Signatures and Examples

  • Starry Night appearance on ultrasound is associated with acute hepatitis in some cases.
  • HCC and metastases may invade portal venous structures and hepatic veins, complicating ultrasound interpretation.
  • AFP elevation is a key marker for hepatoblastoma in infants and children.
  • Ultrasound artifacts and appearances to be aware of:
    • Cavernous hemangioma: irregular echogenic vascular lesion
    • Lipomas and speed artifacts: artifacts may affect interpretation (example shown as Liver Lipoma with speed artifact)
    • FNH central scar can be a distinguishing feature on some imaging modalities

Key Formulas and Numeric References

  • Acute hepatitis recovery window: ext{recovery time}
    ightarrow 4 ext{ months}
  • Chronic hepatitis definition threshold: t > 6 ext{ months}
  • Population/statistic references for US acute viral hepatitis distribution: 60 ext{ extpercent} ext{ (HBV)}, 20 ext{ extpercent} ext{ (HAV)}, 20 ext{ extpercent} ext{ (other types)}
  • Speed of sound references ( imaging context ):
    • v_{ ext{liver}} = 1540 rac{ ext{m}}{ ext{s}}
    • v_{ ext{soft tissue}} = 1450 rac{ ext{m}}{ ext{s}}
    • These values relate to ultrasound speed artifacts discussed in the context of tissue interfaces.