FOCAL NODULAR HYPERPLASIA GRANULOMATA

Focal nodular hyperplasia
This is a benign tumour made up of a proliferation of liver cells with hepatocytes, Kupffer cells and biliary and fibrous elements. It is most commonly found in young women and is usually discovered by chance, being asymptomatic. Its ultrasound characteristics vary, and it may be indistinguishable from hepatic adenoma. It tends to affect the caudate lobe and has the appearance of a homogeneous mass often of similar echogenicity to the liver. It presents a diagnostic difficulty both with CT and ultrasound, as its characteristics can vary.

Colour Doppler shows an increased arterial flow in the mass. The administration of an ultrasound contrast agent displays a characteristic ‘spoked-wheel’ pattern of arteries with a central scar.

The diagnosis can usually be confirmed on MRI scanning (which shows a similar vascular pattern to that of ultrasound contrast scanning) but may occasionally require biopsy proof. Management of this benign mass is usually conservative, with ultrasound follow-up, once the diagnosis has been established, but surgical resection may be necessary in larger lesions.

Granuloma
Granulomata are benign liver masses which are associated with chronic inflammatory liver diseases. They are particularly associated with primary biliary cirrhosis, sarcoidosis or TB. They may be multiple and small, in which case the liver often looks coarse and hyperechoic. More often they are small discrete lesions which may be hypo- or isoechoic, sometimes with a hypoechoic rim like a target, or calcified with distal shadowing. They can undergo central necrosis.

Differential diagnoses include metastases or regenerating nodules.