Type of adenoma
Prevalence
Malignant transformation
MRI characteristics
Inflammatory HCAs
30–50 %
5–10 %
Plain MRI: hyperintense on T2WI; hypointense on T1WI
HNF-1
-mutated HCAs
-mutated HCAs30–35 %
Minimal
Heterogeneous hypointense areas on T1 out-phased sequences with significant signal drops (sensitivity 85 %, specificity 100 %)
On T2WI iso- or hypointense nodule, without significant restriction on DWI
-Catenin-mutated HCAs10–15 %
20–30 %
Biopsy of Hepatic Adenoma
Because of the risk of a beta-catenin type of hepatic adenoma transforming into a hepatocellular carcinoma (HCC), a bi opsy of the hepatic adenoma can be helpful in determining the subtype; however, owing to the vascular nature of the lesion, there is an increased risk of bleeding. As MRI with contrast medium can help to determine the subtype, liver biopsy is seldom required and should be reserved for cases in which the diagnosis is in question.
Management
Incidental Diagnosis, <5-cm Adenoma with No Symptoms
The first step in the management of the lesion should be to stop taking OCPs if they are involved. Then, 6 months after this, repeat imaging should be performed to document regression or stability in size. Surveillance should be carried out every 6 months for 2 years, and, if stable, annual imaging should be performed [21].
Symptomatic, >5-cm Adenomas
Lesions larger than 5 cm should be considered for resection because of their risk of malignant transformation, spontaneous hemorrhage, and symptoms. Nonsurgical management such as embolization is an alternative for high-operative-risk patients. Because of the higher risk of “beta-catenin” (a phenotypic expression )-type adenoma with regard to malignant transformation, patients should be referred for surgical resection irrespective of the size.
Women Contemplating Pregnancy or Who Are Pregnant
Hepatic adenomas are known to grow during pregnancy and hence there is a risk of acute rupture. However, owing to the rare nature of this disease, clear guidelines on managing these lesions in patients planning to be pregnant are not available. However, in general, lesions <5 cm can be observed with no intervention is required [22].
Hepatic Adenomas in Glycogen Storage Disease
Hepatic adenoma in these patients does pose a risk for malignant transformation. Management is slightly different. Nocturnal tube feeding intended to control the disease has been shown to decrease the size of the adenoma [23]. Given the risk for malignant transformation, resection can be offered. Liver transplantation in patients who develop HCC is curative for both HCC and glycogen storage disease.
Liver Adenomatosis
Liver adenomatosis is the condition where >3 to >10 adenomas are present [24, 25]. Nature and disease behavior are the same and hence similar management criteria apply in this subtype.
Adenomas Summary
Adenomas can grow with the use of OCPs.
They are mostly asymptomatic.
They may grow in size in women on hormonal therapy or during pregnancy.
Pregnancy is not contraindicated; however, adenomas measuring more than 5 cm should be addressed surgically before pregnancy.
Adenomas have malignant potential for HCC.
Focal Nodular Hyperplasia
Focal nodular hyperplasia is the second most commonly found hepatic lesion in the liver, with a reported prevalence rate of 0.03–0.3 % in autopsy series [26, 27]. FNH is proposed to be due to the arteriovenous malformation resulting in a response from the hepatic stellate cells, resulting in a “central scar” appearance on imaging.
Focal nodular hyperplasia is most frequently diagnosed incidentally, but can be symptomatic in 20–40 % of cases [28, 29]. It has a female preponderance and is proposed to be present at birth and likely to grow under the effect of female hormones. This is slightly different than hepatic adenoma, which may develop de novo under the influence of hormonal stimulation. However, similar to hemangioma, no clear link is found between the discontinuation of OCPs and a reduction in the size of FNH.
Diagnosis
Diagnosis is usually made by identifying the characteristic features on imaging. Liver enzymes as a rule are normal and tumor markers are not elevated. Differential diagnosis includes hepatic hemangiomas or hepatic adenomas. Caution should be observed as the central scar characteristic of FNH can also be seen in the fibrolamellar type of HCC
Imaging
Most of the lesions are solitary; however, multiple FNHs have been reported in 7–20 % of cases. A diagnosis of FNH can be confidently made by identifying the central scar on imaging.
Ultrasound
Focal nodular hyperplasia can be hyper-, hypo- or isoechoic on ultrasound and a central scar can only be identified in 20 % of the cases.
CT with Intravenous Contrast Medium
An appropriately timed liver CT protocol. The lesion is hyperdense in the arterial phase and either hypodense or isodense with a central scar in the portal venous phase.
MRI
On MRI, the FNH can be isointense or hypointense. A central scar can be seen on the delayed phase. In the T2 phase it is slightly hyperintense or isointense. MRI is the definitive imaging modality for FNH.
Management
Focal nodular hyperplasia usually remains stable and rarely causes symptoms. Unlike hepatic adenoma, it does not have the potential for malignant transformation. Thus, intervention with operative removal is only warranted when symptoms are clearly associated or there is diagnostic uncertainty.
FNH and OCPs
Although there may be a hormonal influence, discontinuation of OCPs is not absolutely recommended. However, in women who wish to continue taking OCPs, an annual ultrasound focusing on the change in size can be performed for 2–3 years. In women who discontinue OCPs, follow-up imaging is not required.
FNH Summary
FNHs are benign lesions in the liver.
They are identified by a central scar on imaging.
They rarely grow.
There is no risk of malignancy.
Nodular Regenerative Hyperplasia
Nodular regenerative hyperplasia (NRH) is a benign transformation of hepatic parenchyma into nodular form. This is described as a consequence of changes in blood flow through the hepatic parenchyma. This, in turn, leads to hyperplasia of the hepatic architecture to compensate for atrophic hepatocytes in ischemic zones, resulting in a nodular appearance. NRH is associated with immunological and hematological disorders, cardiac or pulmonary disorders, and certain drugs and toxins have been implicated in NRH (Table 5.3).
Table 5.2
Imaging characteristics of benign lesions
Ultrasound | CE ultrasound | CT | MRI | |
|---|---|---|---|---|
HCA | Heterogeneous; hyperechoic if steatotic, but anechoic center if hemorrhagic | Arterial phase; hyperenhancement; hypoenhancement in portal phase and no enhancement in late phase | Well-demarcated with peripheral enhancement; homogeneous more often than heterogeneous; hypodense if steatotic, hyperdense if hemorrhagic | HNF-1α: signal lost on chemical shift: moderate arterial enhancement without persistent enhancement during delayed phase IHCA: markedly hyperintense on T2WI with stronger signal peripherally: persistent enhancement in delayed phase B-catenin: inflammatory subtype has same appearance as IHCA; noninflammatory is heterogeneous with no signal dropout on chemical shift, isointense on T1WI and T2WI with strong arterial enhancement and delayed washout |
THCA | Variable appearance | Subcapsular feeding arteries with mixed or centripetal fitting: arterial phase shows hyperenhancement with hypoenhancement and no enhancement in the portal and late phases respectively | Hypo- to isoattenuating | T1WI: heterogeneous and well-defined iso-to hyperintense mass Strongly hyperintense with persistent contrast enhancement in delayed phase |
FNH | Generally isoechoic | Arterial phase: hyperenhancement; portal and late phases: isoenhancement | Central scar. Arterial phase shows homogenous hyperdense lesion; returns to precontrast density during portal phase, which is hypo- or isodense | T1WI: isointense or slightly hypointense. Gadolinium produces early enhancement with central scar enhancement during delayed phase T2WI: slightly hyperintense or isointense |
NRH | Isoechoic/hyperechoic | Isoenhancement during arterial, portal, and late phases | Unenhancing nodules, sometimes hypodense, with variable sizes (most sub-centimeter) | T1WI: hyperintense T2WI: varied intensity (hypo-/iso-/hyperintense) |
Hemangioma | Hyperechoic with well-defined rim and with few intranodular vessels | Arterial phase: discontinuous peripheral nodular enhancement: progressive and centripetal fill in the portal and late phases | Discontinuous peripheral nodular enhancement isoattenuating to aorta with progressive centripetal fill-in | T1WI: hypointense: discontinuous peripheral enhancement T2WI: hyperintense relative to spleen |
SHC | Homogeneous anechoic fluid-filled space without clear walls and with posterior acoustic enhancement | No enhancement during arterial, portal, or late phases. Lack of enhancement because of avascularity | Isodense to water (because of lack of vascularity): well-demarcated | T1WI: hypointense (no enhancement with gadolinium) T2WI: hyperintense to spleen and isointense relative to simple fluid |
HBCA | Anechoic with irregular walls and internal septations | Arterial phase: hyperenhancement of cystic wall, internal septations, and intracystic solid portion: enhancement washes out progressively: hypoenhancement during portal and late phases | Isodense lesion with well-defined thick wall, mural nodules, and internal septations | T1WI: multilocular mass with homogeneous hyperintensity |
Table 5.3
Diseases associated with nodular regenerative hyperplasia
Immunological | Hematological | Drugs and toxins | Cardiac and pulmonary disorders | Other |
|---|---|---|---|---|
Autoimmune Polyarteritis nodosa Rheumatoid arthritis Felty’s syndrome Systemic lupus erythematosus Progressive systemic sclerosis Antiphospholipid syndrome Primary biliary cirrhosis Celiac disease CREST syndrome Primary Sjӧgren’s syndrome Polymyalgia rheumatic Lymphocytic thyroiditis Schnitzler syndrome Immunodeficiency Hypogammaglobulinemia Common variable immunodeficiency Hyper IgM syndrome Bruton syndrome HIV patients Acquired protein S deficiency Thrombophilia | Myeloproliferative neoplasms Chronic myelogenous leukemia Primary myelofibrosis (myeloid metaplasia) Polycythemia vera Essential thrombocytosis Lymphoproliferative neoplasms Chronic lymphocytic leukemia Hodgkin’s lymphoma Non-Hodgkin’s lymphoma Waldenstrӧm’s macroglobulinemia Other Thrombotic thrombocytopenic purpura Sickle cell anemia Mastocytosis Aplastic anemia | Chemotherapeutic agents 6-thioguanine Busulfan and 6-thioguanine Doxyrubicin Cyclophosphamide Chlorambucil Cytosine arabinoside Bleomycin Carmustine Oxaliplatin Azathioprine HIV drugs Nevirapine Didanosine
Related posts: Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
Get Clinical Tree app for offline access
|
