Liver Tumors

Benign Liver Tumors - Mostly Harmless

• Hemangioma: Most common benign liver tumor. Usually asymptomatic, incidental finding. No malignant potential.
  • Micro: Cavernous vascular spaces.
• Focal Nodular Hyperplasia (FNH): Second most common. Well-demarcated, central stellate scar on imaging. No malignant potential.
  • Micro: Nodular architecture, fibrous septa, anomalous arteries, bile duct proliferation.
• Hepatic Adenoma: Less common. Strong association with oral contraceptive pills (OCPs) and anabolic steroids.
  • Risk of hemorrhage (especially if >5 cm) and malignant transformation (rare).
  • Subtypes: HNF1A-inactivated, inflammatory, β-catenin activated (higher malignancy risk).

⭐ Hepatic adenomas are associated with OCP use and carry a risk of hemorrhage or malignant transformation, particularly the β-catenin activated subtype and larger lesions (>5 cm).

Hepatocellular Carcinoma (HCC) - The Big Bad

• Risk Factors: Chronic HBV/HCV, cirrhosis (esp. alcoholic, NAFLD), Aflatoxin B1 (Aspergillus), hemochromatosis, Wilson's.
• Key Mutations: TP53 (Aflatoxin B1 often induces G:C → T:A at codon 249), beta-catenin pathway activation.
• Tumor Marker: Alpha-fetoprotein (AFP) often elevated (>400 ng/mL), but lacks specificity.
• Morphology:
  • Gross: Unifocal, multifocal, or diffusely infiltrative; frequently bile-stained (greenish).
  • Micro: Trabecular (most common), pseudoacinar, solid patterns. Cells resemble hepatocytes.
• Fibrolamellar Variant:
  • Younger patients (<35 yrs), typically no cirrhosis; better prognosis.
  • Micro: Distinctive large 'oncocytic' cells (eosinophilic cytoplasm), lamellar fibrosis.

⭐ Aflatoxin B1 (Aspergillus in food) is a major HCC risk, linked to characteristic TP53 mutations.

Cholangiocarcinoma - Bile Duct Villains

• Risk Factors: Primary Sclerosing Cholangitis (PSC), liver flukes (Clonorchis sinensis, Opisthorchis viverrini), choledochal cysts, hepatolithiasis, Caroli's disease, Thorotrast.
• Classification by location:
  • Intrahepatic (peripheral): Within liver parenchyma.
  • Perihilar (Klatskin tumor): At hepatic duct bifurcation. Most common.
  • Distal (extrahepatic): Common bile duct, often ampullary.
• Histology: Adenocarcinoma (mucin-producing glands), prominent desmoplastic stroma (dense collagen).
• Tumor Markers: ↑ CA19-9 (most specific), ↑ CEA.

⭐ Klatskin tumors are cholangiocarcinomas specifically arising at the confluence (bifurcation) of the right and left hepatic ducts.

Metastatic Liver Tumors - Invaders Incognito

• Liver: Extremely common metastatic site due to dual blood supply; more frequent than primary liver cancers.
• Common Primaries: Colorectal (most common), lung, breast, pancreas, stomach.
• Gross: Typically multiple, variably sized nodules; 'cannonball' lesions (esp. lung, renal). Central umbilication/necrosis common.
• Vs. Primary: Usually multiple; primary often solitary (except multifocal HCC). Known extrahepatic primary is key.

⭐ Metastatic tumors are the most common malignancies found in the liver, often outnumbering primary liver cancers by up to 20:1.

Pediatric Liver Tumors - Tiny Tumors, Big Trouble

• Hepatoblastoma: Most common primary liver tumor in early childhood (typically < 3 years).
  • Associations: Beckwith-Wiedemann syndrome, Familial Adenomatous Polyposis (FAP), low birth weight.
  • Histology: Epithelial (fetal, embryonal, macrotrabecular) & mixed epithelial-mesenchymal types.
  • Serum AFP: Markedly ↑↑ in > 90% cases.

⭐ Hepatoblastoma is strongly associated with elevated serum alpha-fetoprotein (AFP) levels and syndromes like FAP and Beckwith-Wiedemann syndrome. Other pediatric liver tumors include infantile hemangioendothelioma (most common benign) and mesenchymal hamartoma.

High‑Yield Points - ⚡ Biggest Takeaways

• HCC: Most common primary malignancy; linked to Hepatitis B/C, cirrhosis, aflatoxin.
• AFP: Key tumor marker for HCC; not always elevated.
• Fibrolamellar HCC: Younger patients, no cirrhosis, better prognosis, oncocytic cells.
• Hepatoblastoma: Most common liver tumor in early childhood (<3 years).
• Cavernous Hemangioma: Most common benign liver tumor; often incidental.
• FNH: Benign tumor with characteristic central stellate scar.
• Metastases: More common in liver than primary tumors.