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US of VMs demonstrate a sponge-like network of tubular
structures with low velocity or no venous
fl
ow. The vessels
are easily compressible with the US probe.
MRI is the best imaging method to de
fi
ne the full
anatomical extent of VMs.
31
VMs are serpiginous T2
hyperintense lesions, which often show phleboliths. Hae-
morrhage, thrombosis, or phleboliths may reveal variable
degree of pre-contrast high T1 hyperintensity. Some degree
of fat tissue or muscle tissue may be observed interspersed
between the venous channels. Spontaneous thrombosis and
thrombolysis can occur with VMs, which results in elevated
D
-dimer levels (
>
0.5
m
g/ml) in approximately 42% of pa-
tients.
D
-dimer levels are often very high even in otherwise
healthy patients.
32
Phleboliths are often observed (round/
oval shaped T2 hypointense foci) representing calci
fi
cation
within the veins. DCE-MRA demonstrates enhancement in
the venous phase that may be progressive in nature, typical
for VMs (
Figs 1
and
6
).
33
Lymphatic malformation
Lymphatic malformations (LMs) are soft, compressible
lesions of lymphatic origin (
Figs 1
and
7
). These have also
been referred to as cystic hygromas or lymphangiomas, but
these terms are confusing and should be avoided. LMs are
collections of cystic spaces
fi
lled with chylous material.
34
These cystic spaces may be macrocystic, microcystic, or
mixed. Microcystic LMs are not as compressible as macro-
cystic LMs. The microcysts may be so small that they are
indistinguishable on cross-sectional imaging.
US evaluation shows no
fl
ow within the major spaces,
although small arteries and veins can traverse the intersti-
tial spaces. MRI appearance can be variable on T1-weighted
imaging for LMs depending on internal haemorrhage and
in
fl
ammation, but usually of high signal on T2 weighting
and shows mild peripheral enhancement with no internal
enhancement with gadolinium. Diffuse microcystic LM may
result in mild diffuse enhancement of the cyst walls and
may be challenging diagnosis for the radiologist.
Capillary malformation
Capillary malformations (CMs) are commonly known as
“
port wine stains
”
as well as nevus
fl
ammeus and can be
confused with IH. They are typically red or pink in infancy
and may darken with age. They grow in proportion with the
patient and do not resolve spontaneously. CMs in certain
locations can be associated with other abnormalities. For
Figure 13
(a) A 4-year-old female patient with extensive blueness to her left leg and buttock region. She had no leg length discrepancy on
measurement. (b
e
c) Coronal T2-weighted image shows extensive VM in
fi
ltrating the muscle groups in the left lower extremity and buttock.
Note in
fi
ltration in the skin. (d) DCE-MRA shows enhancement of the VM in the venous phase.
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