Review Note

Last Update: 02/18/2024 05:30 AM

Current Deck: Part 2::1. Subsites::Gastrointestinal tract::Liver metastases

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GI | Liver mets | 2.1 | Differential diagnosis | List differential diagnoses for liver metastases and briefly describe their clinical and imaging characteristics
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  • Prevalence
    • Incidental hepatobiliary findings occur in ~6% of CT
  • Differential diagnosis
    • Benign lesions
      • Hepatic haemangioma (aka cavernous haemangiomas)
        • Epidemiology
          • I: Most common benign liver lesions
          • A: May be diagnosed at any age; most commonly diagnosed (80%) betewen 30-50yo
          • S: More commo in women M:F 1:3
        • Imaging appearance:
          • Most often solitary but may be multiple
        • Clinical features:
          • Majority asymptomatic
          • Excellent prognosis
      • Focal nodular hyperplasia
        • Pathology: Benign liver lesion composed of a proliferation of hyperplastic hepatocytes surrounding a central stellate scar
        • Epidemiology
          • I: Prevalance 0.2-1.6% as incidental finding on CT or US
          • S: More common in women
        • Imaging appearance: 
          • Typically solitary
      • Hepatocellular adenoma (aka hepatic adenoma)
        • Pathology: Benign liver lesion that develops in an otherwise normal-appearing liver
        • E: 
          • I: Uncommon
          • S: More common in young women
          • RFs: 
            • Estrogen-containing medications
            • Glycogen storage disease
            • Metabolic syndrome
        • Imaging apperance: Solid, typically solitary lesion
      • Regenerative nodules
        • Develop in response to liver injury
        • Comprised of a proliferation of hepatocytes and surrounding stroma
        • Typically seen in the setting of cirrhosis
    • Malignant lesions
      • Hepatocellular carcinoma
        • Primary liver tumour, develops in setitng of chronic liver disease (esp. cirrhosis of any cause, or chronic hepatitis B infection)
      • Cholangiocarcinoma
        • Arise from the epithelial cells of intra- and extra-hepatic bile ducts
        • May be foudn incidentally during the early stage of disease
        • RFs: 
          • Primary sclerosing cholangigtis
          • Firbopolycystic liver disease (e.g. choledochal cysts)
          • Hepatolithiasis
      • Metastatic disease
        • RFs: history of malignancy
  • Imaging characteristics
    • Size
      • Most incidental lesions <1cm are benign; while some small lesions may be difficult to definitively characterise by imaging mehtods
      • Most lesions >=1cm can be diagnosed either by further imaigng (e.g. MRI) and/or histology
      • Marign - benign lesions typically have smooth margins
      • Enhancement pattern on contrast-enhanced imaging - most lesions have characteristic enhancement features
        • Hepatic haemangioma:
          • Early phase: Peripehral nodular enhancement
          • Late phase: Centripetal pattern or "filling in" duirng the late phase
          • Lesion usually opacifies after a delay of >=3 minutes and remains isodense or hyperdense on delayed scans
        • Hepatocellular adenoma
          • Early phase: Well-demarcated leison with peripheral enhancement (reflects the large subcapsular feeding vessels)
          • Portal venous phase: Centripetal flow
        • Focal nodular hyperplasia
          • Non-contrast: Hypo- or isodense with a central scar
          • Arterial phase: Hyperdense
          • Portal venous phase: Typically isodense, although the central scar may become hyperdense as contrast diffuses into the scar
        • Hepatocellular carcinoma
          • CT
            • Arterial phase: Hypervascular relative to liver parenchyma
            • Later phases: Washout of contrast
          • MRI
            • T1: low intensity
            • T2: highintensity
        • Intrahepatic cholangiocarcinoma
          • CT
            • Hypodense lesion with peripheral (rim) enhancement
          • MRI
            • T1: Hypointense
            • T2: Hyperintense
            • Dynamic images: Peripheral rim enhancement followed by progressive and concentric filling-in of the tumour with contrast material
        • Liver metastases
          • CT
            • Colon, stomach, pancreas: Usually lower attenuation (i.e. are darker) in contrast to hte brighter surrounding liver parenchyma
            • Hypervascular metastases (e.g. neuroendocrine tumour, RCC) appear as rapidly enhacning lesions visible on the arterial phase
          • MRI
            • T1: low signal 
            • T2: Moderately high signal
  • Diagnostic approach for and incidental liver lesion
    • Risk factors for HCC (Cirrhosis, chronic hepatitis B infection)
      • Further tailored imaging for HCC
    • History of malignancy
      • Further evaluation depends on the primary malignancy
    • Neither HCC risk factors or history of malignancy
      • Imaging features of haemangioma: Typical features (homogenous, hyperechoic, well-delineated), size <3cm) -> no further imaging necessary
    • Contrast enhanced multiphase cross-sectional imaging (e.g. MRI)
      • If above insufficient to make diagnosis; options include:
        • Obtain tissue for histology (biopsy or surgical resection)
        • Monitor with surveillance imaging (individualised, but usually 6-12 months)
Further information, not for memorising (no card)
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