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ABDOMINAL ULTRASOUND
mass. The administration of an ultrasound contrast
agent displays a characteristic ‘spoked-wheel’ pattern
of arteries with a central scar. 7
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.
C
Figure 4.11 cont’d (C) Wedge-shaped area of fatty
infiltration in the right lobe.
Lipoma
The hepatic lipoma is a relatively rare, benign
hepatic tumour which is very similar in nature and
acoustic appearance to focal fatty change. It differs
in that it is a discrete tumour of fatty deposition
rather than an infiltrative process and so can exert
a mass effect on surrounding vessels if large. The
fat content makes the lipoma hyperechoic compared
to the surrounding liver tissue.
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 (Fig. 4.12). It presents
a diagnostic difficulty both with CT and ultrasound,
as its characteristics can vary. 6 Colour
Doppler shows an increased arterial flow in the
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 (Fig. 4.13). They
can undergo central necrosis.
Differential diagnoses include metastases or
regenerating nodules.
Hepatic calcification
Calcification occurs in the liver as a result of
some pathological processes and may be seen
following infection or parasitic infestation. It
may be focal (usually the end stage of a previous
abscess, haematoma or granuloma) which
usually indicates that the lesion in question is no
longer active. It may also be seen within some
metastases.
Calcification may also be linear in nature, following
the course of the portal tracts. This can be
associated with old TB or other previous parasitic
infestations.
Occasionally hepatic calcification is seen in
children or in the fetus. This is usually not a significant
finding but prenatal infection should be
excluded with a TORCH (toxoplasmosis, rubella,
cytomegalovirus and HIV) screen. Calcification,
which casts a strong and definite shadow, should
be distinguished from air in the biliary tree (Fig.
3.46), which casts a reverberative shadow and is