HNF 1 alpha mutated hepatic adenoma

HNF 1 alpha mutated hepatic adenomas are a genetic and pathologic subtype of hepatic adenoma. Their appearance and prognosis are different from other subtypes.

Epidemiology

They are the second most common (30-35%) hepatic adenoma after the inflammatory subtype. They occur only in female patients, most with a history of oral contraceptive (OCP) use.

Clinical presentation

May develop right upper quadrant pain from intratumoral hemorrhage.

Radiographic features

This subtype of adenoma is multiple in ~50%.

MRI

• T1: isointense or hyperintense relative to liver
• T1 C+ (Gd)
  • moderate arterial phase enhancement (less than inflammatory subtype)
  • less likely to have persistent enhancement on portal venous and delayed phases, cf. inflammatory subtype
• IP/OP: signal drop out on the out-of-phase sequence
• T2: isointense to mildly hyperintense

Treatment and prognosis

If a hepatic adenoma is suspected on imaging, patients usually stop their oral contraceptive and the lesion regresses.

If the lesion does not regress, then one treatment pathway suggests:

• ≥5 cm: resection (hepatic adenomas larger than 5 cm are at increased risk of hemorrhage)
• <5 cm: biopsy

Tissue diagnosis then confirms or changes the adenoma subtype. If HNF 1 alpha mutated subtype is confirmed, management consists of:

• clinical and imaging follow up of any remaining adenomas until menopause
• resection or thermal ablation of enlarging adenomas that grow >5 cm
• genetic counseling if there is hepatic adenomatosis, familial history of hepatic adenoma, or MODY3 (mature onset diabetes of the young, type 3)

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

Differential diagnosis

• other types of hepatic adenoma
  • inflammatory hepatic adenoma
  • beta catenin mutated hepatic adenoma
  • unclassified hepatic adenoma
• hepatocellular carcinoma (HCC)
  • washout tends to leave the lesion hypointense compared to the rest of liver
  • different demographics
  • may be difficult to distinguish if well differentiated ⁷
• focal nodular hyperplasia (FNH)
• liver metastases (hypervascular) 
• for other differential considerations, see the main article: hepatic adenoma