Comprehensive Study Notes on Benign and Malignant Liver Tumors

Case Report: Clinical Presentation and Diagnostic Workflow

• Patient Profile: A $60$-year-old patient.

• Medical History:

  • Type II diabetes for $15$ years.

  • Smoking history: $20$ pack-years.

• Symptomatology (Presenting for $1$ year):

  • Impaired general condition: Asthenia, anorexia, and significant weight loss.

  • Abdominal pain.

  • Steatorrhea.

• Radiological Findings:

  • Abdominal Ultrasound: Identified lesions in the hepatic area and the pancreatic area (tail of the pancreas).

  • Abdominal CT Scan: Revealed a multinodular liver and a primary pancreatic lesion.

• Pathological Investigation:

  • Procedure: Liver biopsy performed using a Chiba biopsy needle under ultrasound guidance (ONP - echo-guided biopsy).

  • Management: Sample preserved in $10\%$ Neutral Buffered Formalin ($pH \, 6.8 - 7.2$ at $25^{\circ}C$).

• Pathological Diagnosis Workflow:

  1. Reception and Macroscopy.

  2. Inclusion and Paraffin embedding.

  3. Microtomy (sectioning).

  4. Staining and Immunohistochemistry (IHC).

  5. Specialized techniques: Molecular biology.

  6. Reading, report writing, and Secretariat.

• Case Outcome: The clinicopathological correlation and IHC panel revealed a hepatic localization of a pancreatic acinar adenocarcinoma (metastasis).

Introduction to Liver Tumors

• Classification: Liver tumors are divided into Benign and Malignant categories.

• Malignant Tumors (MT):

  • Metastases: These are the most common malignant liver tumors ($+++$), primarily originating from the digestive tract.

  • Primary Malignant Liver Tumors: These arise from the normal histological constituents of the liver parenchyma (hepatocytes, biliary cells, vessels, etc.).

  • Hepatocellular Carcinoma (HCC): The most frequent primary tumor ($+++$), typically developing on a background of cirrhosis.

• Clinical Practice Goal: The primary objective is to differentiate between secondary (metastatic) and primary liver tumors.

Anatomical and Histological Review

• The Adult Liver:

  • Weight: Approximately $1200 - 1500\,g$.

  • Anatomy: Comprised of four lobes: Right lobe (Lobe droit), Left lobe (Lobe gauche), Caudate lobe (Lobe caudé), and Quadrate lobe (Lobe carré).

  • Ligaments: The falciform ligament (Ligament falciforme) separates the main lobes.

• Histological Unit: The hepatic lobule.

  • Structure: Portions include the central vein (Veine centro-lobulaire), hepatic cells (Hepatocytes), and the interlobular space.

  • Portal Tract: Located at the periphery of the lobule, containing one or more sections of the bile duct, portal vein, and hepatic artery.

  • Limiting Plate: The hepatocytic limiting plate (Lame bordante hépatocytaire) represents the interface between the hepatic parenchyma and the portal mesenchyme.

• Microscopic Components:

  • Space of Disse: A gap between hepatocytes and the sinusoidal endothelium.

  • Sinusoids: Lined by endothelial cells and populated by Kupffer cells (macrophages).

  • Stellate Cells: Quiescent cells located in the space of Disse.

  • Bile Canaliculus: Formed by the plasma membranes of adjacent hepatocytes.

Tissue Origins of Primary Malignant Tumors

• Hepatocytes: Lead to Hepatocellular Carcinoma (Hepatocarcinoma).

• Biliary Structures (Bile Ducts): Lead to Cholangiocarcinoma.

• Vascular Structures (Sinusoids, Arteries, Veins): Lead to Hemangiosarcoma/Angiosarcoma.

• Mixed Tumors: Combined Hepatocyte and Biliary cell origin (e.g., Focal Nodular Hyperplasia is a benign mixed-like node, but not a true neoplasm).

• Embryonal Origin: Hepatoblastoma.

Study Materials and Diagnostic Methods

• Sampling Techniques:

  • Liver Biopsy: Surgical, Percutaneous (image-guided), or Transjugular.

  • Hepatectomy Specimen: Total (for transplantation) or Partial (for tumor resection).

• Standards for Percutaneous Biopsy:

  • Minimum specimen length: $10\,mm$.

  • Must contain at least $6$ portal tracts for adequacy.

• Clinical Indications for Biopsy: Monitoring cirrhosis, staging primary digestive tumors, evaluation of jaundice, liver mass, or right upper quadrant pain.

• Biopsy Contraindications:

  • Hemostasis disorders (risk of bleeding).

  • Hypervascular lesions.

  • Suspicion of hydatid cyst (risk of anaphylaxis/dissemination).

• Imaging Modalities: Ultrasound, CT, and MRI to assess size, number, location, vascularization, and portal venous extension (crucial for HCC).

• Serum Biomarkers:

  • Alpha-fetoprotein (AFP): High levels indicate HCC or Hepatoblastoma.

  • CA 19-9: Marker for biliary tumors.

  • CEA: Marker for digestive carcinomas.

• Non-Biopsy Diagnoses: Biopsy is often unnecessary if imaging and markers are definitive for HCC (cirrhosis + nodule + portal thrombosis + high AFP), Focal Nodular Hyperplasia (characteristic MRI appearance), or Hemangiosarcoma (typical CT enhancement).

Secondary (Metastatic) Malignant Tumors

• Prevalence: More frequent than primary tumors.

• Primary Sites:

  • Digestive ($+++$): Colon, stomach, pancreas.

  • Other: Breast, lung, prostate, melanomas, lymphomas.

• Macroscopy: Often multinodular with variable sizes (mm to cm).

• Immunohistochemical (IHC) Profiling (CK7 and CK20):

  • $CK7^+ / CK20^-$: Suggests breast, non-mucinous ovary, endometrium, lung, mesothelioma, thyroid, salivary glands, or papillary renal carcinoma.

  • $CK7^+ / CK20^+$: Suggests pancreato-biliary tract ($74\%$ probability), mucinous ovary, or stomach.

  • $CK7^- / CK20^+$: Strong probability ($78\%$) of colorectal origin, also Merkel cell carcinoma (with dot-like staining).

  • $CK7^- / CK20^-$: Suggests HCC, clear cell renal carcinoma, prostate, or adrenal cortex.

• Advanced IHC Markers:

  • CDX2 / SATB2: Used for colorectal cancer confirmation.

  • Synaptophysin (SYN) / Chromogranin (CGN): Used for endocrine/neuroendocrine markers.

Primary Malignant Liver Tumors

1. Hepatocellular Carcinoma (HCC)

• Context: Develops in cirrhosis ($80\%$ of cases).

• Risk Factors: Male sex, age > 50 years, macronodular or long-standing cirrhosis, and viral hepatitis (B or C).

• Macroscopy: Polychrome (beige, green from bile, yellow from lipids, red from blood); often hemorrhagic and necrotic; frequent portal vessel extension.

• Microscopy:

  • Architecture: Trabecular (separated by vascular spaces) in well-differentiated forms; acini in moderate; sheets in poorly differentiated.

  • Cells: Polygonal, producing bile, glycogen, or lipids.

2. Fibrolamellar HCC

• Context: Occurs in a healthy liver.

• Patient Profile: Children and young adults (< 1\% of HCCs).

• Characteristics: Normal AFP; unknown etiology; better prognosis than classic HCC.

• Microscopy: Large eosinophilic tumor cells arranged in trabeculae within lamellar fibrosis.

3. Intrahepatic Cholangiocarcinoma

• Context: Second most frequent primary malignant epithelial tumor ($10\%$).

• Patient Profile: Older subjects (approx. $60$ years).

• Anatomical Types:

  • Peripheral/Intrahepatic ($15\%$).

  • Hilar (Klatskin tumor) ($60\%$).

  • Main bile duct ($25\%$).

• Risk Factors: Cirrhosis, Hepatitis B/C, MAFLD, Alcohol, Smoking, Primary Sclerosing Cholangitis (CSP), Caroli disease, and Liver flukes (parasites).

4. Hepatoblastoma

• Context: Embryonal tumor in healthy liver; child < 3 years.

• Presentation: Tumoral hepatomegaly and massive increase in serum AFP.

• Genetic Associations: Familial Adenomatous Polyposis, Beckwith-Wiedemann Syndrome, and Trisomy 18.

• Screening: In high-risk children, abdominal ultrasound and AFP every $3$ months until age $4$.

• Pathology: Can be Pure epithelial ($60 - 70\%$) or Mixed epithelial and mesenchymal.

Benign Liver Tumors

• Hemangioma:

  • Prevalence: $3\%$ of the population.

  • Clinical: Often asymptomatic, small, incidental finding on ultrasound.

  • Diagnosis: Radiological (MRI: Very hyperintense on T2, slow centripetal enhancement). Biopsy is contraindicated due to hemorrhage risk.

• Hepatocellular Adenoma:

  • Profile: Young women linked to oral contraception.

  • Risk: Large size ($5 - 15\,cm$) with high risk of spontaneous rupture or intraperitoneal hemorrhage.

  • Treatment: Surgical resection.

• Focal Nodular Hyperplasia (FNH):

  • Nature: Not a true tumor, but a hyperplastic/regenerative response to vascular abnormalities.

  • Profile: Women age $20 - 50$; oral contraceptive link is not established.

  • Imaging: Homogeneous lesion with a pathognomonic central fibrous scar.

  • Microscopy: Fibrous bands, thick-walled vessels (hyperarterialization), ductular hyperplasia, and hepatocytes without atypia.

  • Course: No malignant transformation; treatment usually unnecessary.