Fact-sheet: Hepatic adenoma
Updated on 10/21/2022 at 11:35 AM
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Definition
Benign hormone-induced primary liver tumor
Rare (10 times less common than FNH)
Solitary in 70-80% of cases.
Hepatic adenomatosis if more than 10 lesions
Macroscopy:
- Well-defined nodule, 1 to 20 cm, richly vascularized
- Often lighter than the adjacent hepatic parenchyma, sometimes similar, unless necrosis, steatosis, or hemorrhagic changes are present
Microscopy:
- Proliferation of regular hepatocytes
- No atypia or mitosis
- Histomolecular classification into 4 subtypes (see below)
Clinical features
Rare, prevalence of 0.03%
Female/male sex ratio of 9/1
- Rare in men
Mean age 30-40 years
Oral contraception in 85% of cases
- Most often asymptomatic in 80% of cases
- Hepatomegaly or heaviness if large
- Acute abdomen presentation in cases of hemorrhagic adenoma, with or without subcapsular hematoma or hemoperitoneum
- Especially if adenoma > 5 cm
Laboratory findings
Normal laboratory findings in 50% of cases
Sometimes: anicteric cholestasis and inflammatory syndrome, elevated transaminases
Ultrasound
Incidental finding but nonspecific appearance on B-mode
Contrast-enhanced ultrasound (CEUS) (in combination with MRI):
- Effective for differentiating between adenomas and FNH
- Very high temporal resolution
- Rapid arterial enhancement
- Centripetal filling, never a central scar
- Telangiectatic type: Isointense on portal venous phase, delayed central hyposignal
- Steatotic type: Isointense on portal venous and delayed phases
CT
Lesion often incidentally detected on CT, but with little to no characterization possible on CT
MRI
Reference examination for precise characterization of adenomas: confirms the diagnosis, distinguishes subtypes, and performs exhaustive lesion count, particularly in cases of adenomatosis (more than 10 lesions)
After administration of hepatocyte-specific contrast agent on delayed phase: signal drop relative to adjacent parenchyma (unlike FNH)
MRI semiology correlates with the 4 molecular subtypes of adenomas
- Telangiectatic or inflammatory adenoma
- Steatotic background liver
- Spontaneous T1 hyperintensity
- Marked and homogeneous T2 hyperintensity, more pronounced than that of the spleen
- Intense early enhancement, sustained over time
- Steatotic adenoma with HNF1-alpha mutation
- Normal background liver
- Diffuse and homogeneous fatty overload (marked signal drop on OP, Sp = 100%)
- Low initial enhancement without delayed enhancement after injection
- Beta-catenin-mutated adenoma
- No specific MRI feature
- Unclassified adenoma
- No specific MRI feature
Management
Discontinuation of oral contraceptives in all cases in women
Classification
- Telangiectatic or inflammatory adenoma (35-40%). Occurs preferentially on a background of chronic liver disease. 10% progression to hepatocellular carcinoma (HCC).
- Adenoma with beta-catenin gene mutation (15-20%) with high risk of progression to HCC
- Adenoma with HNF1-alpha mutation, steatotic, with benign course
- Non-specific or unclassified adenoma
Differential diagnosis
- Focal nodular hyperplasia
- Hepatocellular carcinoma
