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PATHOLOGY OF THE LIVER AND PORTAL VENOUS SYSTEM 89
A
B
C
Figure 4.12 (A) Focal nodular hyperplasia in the left lobe (arrows), which is isoechoic with normal liver tissue.
(B) Following administration of microbubble contrast agent, the FNH displays a ‘spoked-wheel’ pattern of vascular
enhancement during the early arterial phase. (C) The same lesion seconds later, showing a central scar.
usually associated with previous biliary interventions,
such as ERCP, sphincterotomy or stent
placement (Fig. 4.14).
MALIGNANT FOCAL LIVER LESIONS
The ‘mass effect’
This term describes the effect of a focal mass,
whether benign or malignant, on surrounding
structures and is a useful diagnostic tool. It implies
the lesion’s displacing or invasive nature, i.e. the
displacement of vessels and/or invasion or distortion
of adjacent structures and tissues as a result of
the increasing bulk of a lesion. This effect differentiates
a true mass from an infiltrative process such
as steatosis, or an artefact.
Masses which are large and/or closely adjacent
to a vessel demonstrate the effect more readily. The
mass effect does not, of course, differentiate
benign from malignant masses, or help in any way
to characterize the mass. It is particularly useful
when the mass is isoechoic compared with normal
liver (Fig. 4.15). In such cases, the effect of the
mass on adjacent structures may be the main clue
to its presence.