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Hepatic adenoma (HA) is a benign, vascular liver tumor composed of hepatocytes, lacking bile ducts and portal tracts. It carries a risk of hemorrhage and malignant transformation, especially in certain histologic subtypes.

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Etiopathogenesis

• Most common in women of reproductive age, particularly those on long-term oral contraceptives.

Risk factors include:

• Anabolic steroid use (especially in men)
• Glycogen storage disease type I (von Gierke)
• Klinefelter’s syndrome
• Familial adenomatous polyposis (FAP).

![Risk factors of hepatocellular adenomas (HCA):

Various genetically-defined predisposing factors are depicted in green. Blue bars represent environmental factors frequently associated with the development of HCA, second to none the use of oral contraceptives in females. Orange boxes in the lowermost line represent three distinguishable molecular pathways, which define the main subgroups of HCA. GSD: glycogenosis; FAP: familiar adenomatous polyposis; ATM: alcohol, tobacco, metabolic syndrome; JAK: Janus kinase; STAT: signal transducer and activator of transcription; HNF1α: hepatocytic nuclear factor 1 α.

Goltz D, Fischer HP. Current Proceedings in the Molecular Dissection of Hepatocellular Adenomas: Review and Hands-on Guide for Diagnosis. International Journal of Molecular Sciences. 2015;16(9):20994-21007. doi:https://doi.org/10.3390/ijms160920994](attachment:d1123b13-17a6-4593-a3eb-c2b1dff46ec5:ijms-16-20994-g001.png)

Risk factors of hepatocellular adenomas (HCA):

Various genetically-defined predisposing factors are depicted in green. Blue bars represent environmental factors frequently associated with the development of HCA, second to none the use of oral contraceptives in females. Orange boxes in the lowermost line represent three distinguishable molecular pathways, which define the main subgroups of HCA. GSD: glycogenosis; FAP: familiar adenomatous polyposis; ATM: alcohol, tobacco, metabolic syndrome; JAK: Janus kinase; STAT: signal transducer and activator of transcription; HNF1α: hepatocytic nuclear factor 1 α.

Goltz D, Fischer HP. Current Proceedings in the Molecular Dissection of Hepatocellular Adenomas: Review and Hands-on Guide for Diagnosis. International Journal of Molecular Sciences. 2015;16(9):20994-21007. doi:https://doi.org/10.3390/ijms160920994

Pathology

• Composed of hepatocytes with glycogen and fat, no portal triads or bile ducts.
• Kupffer cells generally absent (or sparse).
• May have fibrous pseudocapsule and sometimes central scar (though less common and less prominent than in FNH).
• Tendency to outgrow blood supply, leading to hemorrhage, infarction, or necrosis.

Histologic subtypes:

There are four histologic subtypes, each with distinct features and risks:

1. Inflammatory adenoma – Most common; high bleeding risk; may show fat and inflammation.
2. HNF1α-mutated – Associated with FAP and von Gierke’s disease; usually multiple; contains fat.