Inflammatory hepatic adenoma

Inflammatory hepatic adenomas are a genetic and pathological subtype of hepatic adenoma. Their appearance and prognosis is different than other subtypes and has the highest incidence of haemorrhage amongst hepatic adenoma subtypes.

Epidemiology

Most common subtype of hepatic adenoma (40-50%). Occur most commonly in women with oral contraceptive pill (OCP) usage.

Clinical presentation

Fever, leucocytosis, elevated CRP, and elevated liver function tests (LFTs) are compatible with an inflammatory hepatic adenoma.

Radiographic features

MRI

• T1: isointense or mildly hyperintense relative to liver
• T1 C+ (Gd): ​marked arterial enhancement that fades in the portal venous phase and delayed phase
• IP/OP: no hypointensity on the out-of-phase sequence
• T2
  • ​usually hyperintense
  • an atoll sign may be seen: peripheral rim of high T2 signal intensity with the centercentre of the lesion appearing isointense to the background liver; this is considered a characteristic sign

Treatment and prognosis

Inflammatory hepatic adenomas have a higher risk of bleeding than other subtypes (haemorrhage occurs in ~30% of this subtype). Adenomas larger than 5 cm are also at increased risk of haemorrhage.

If imaging shows an inflammatory hepatic adenoma subtype, then patients usually stop OCPs and the lesion regresses.

If it does not regress, then one treatment pathway suggests:

• ≥5 cm: resection
• <5 cm: biopsy

Tissue diagnosis then confirms or changes the adenoma subtype. If inflammatory pathologic subtype, then:

• clinical and imaging follow up of any remaining adenomas until menopause
• resection or thermal ablation of enlarging adenomas that grow >5≥5 cm

ItThere is also a very small risk that a hepatic adenoma may develop into a hepatocellular carcinoma (HCC).

Differential diagnosis

• other types of hepatic adenoma
  • HNF 1 alpha mutated hepatic adenoma
  • beta catenin mutated hepatic adenoma
  • unclassified hepatic adenoma
• hepatocellular carcinoma (HCC)
  • washout tends to leave the lesion hypointense c.fcf. to rest of liver
  • different demographics
  • may be difficult to distinguish if well differentiated-differentiated
• focal nodular hyperplasia (FNH)
  • there may be an overlap in appearance when using gadoxetic acid (Eovist) ⁴
• liver metastases (hypervascular) 
• for other differential considerations, see the main article: hepatic adenoma