B39. Benign tumors and cysts of the liver

The most important benign liver tumours and tumour-like lesions are hepatic haemangioma, hepatic adenoma, focal nodular hyperplasia, and bile duct adenoma. See also liver cysts.

Benign liver tumours are mostly asymptomatic. The most common symptom is upper right quadrant pain but ruptured or haemorrhaging hepatic adenomas may cause haemodynamic instability. Asymptomatic liver tumours are usually discovered incidentally on ultrasound or CT imaging.

Focal nodular hyperplasia

Focal nodular hyperplasia (FNH) is a benign lesion consisting of hyperplastic hepatocytes nodules with a characteristic central stellate scar. It is localized and well-demarcated. It’s not a true neoplasm but instead a hyperplastic response to a vascular malformation or portal duct injury.

FNH is the second most common benign liver lesion. It occurs most commonly in middle-aged females. Contraceptives may increase the risk. These lesions are mostly asymptomatic and have no malignant potential and is therefore not usually removed.

FNH is diagnosed when a homogenous lesion with central stellate scar is visualised on ultrasonography, CT, or MRI. FNH lesions which lack one of the three characteristic classic features on imaging is known as “non-classic” FNH. Non-classic FNH requires biopsy for differential diagnosis.

FNH only require treatment if they’re large, symptomatic, or ruptured.

Hepatic adenoma

Hepatic (or hepatocellular) adenoma is a benign tumor of hepatocytes. It’s rare. It is associated with contraceptive use and is therefore most common in females.

Hepatic adenomas are problematic as they have the possibility to rupture or haemorrhage, which may be life-threatening. They may also undergo malignant transformation into hepatocellular carcinoma. For these reasons, they should be surgically removed and contraception should be stopped. Unlike hepatic haemangioma and FNH, hepatic adenoma is heterogenous on imaging.

Surgical removal of hepatic adenoma is usually advised due to the potential complications, along with stopping contraceptive use.

Hepatic haemangioma

Hepatic haemangioma is a benign vascular lesion of the liver, and the most common liver tumour. It is associated with contraceptive use and is therefore most common in females. The peak incidence is in the 30 – 50s. They’re mostly asymptomatic and have no malignant potential and is therefore not usually removed.

It’s a type of cavernous angioma. These haemangiomas are composed of many endothelium-lined vascular spaces separated by fibrous septa.

Hepatic haemangioma is diagnosed in the context of characteristic features on ultrasound, no known neoplastic disease, and normal liver function tests. On CT and MRI with contrast there is a characteristic initial discontinuous enhancement followed by subsequent centripetal enhancement. Haemangiomas must not be biopsied due to the high risk of severe bleeding.

Haemangioma only require treatment if they’re large, symptomatic, or ruptured.

Bile duct adenoma

Bile duct adenoma is a rare benign condition of the bile ducts that is often found incidentally. It can easily be confused with a malignant tumor and can therefore interfere with differential diagnosis.