Diagnosis
The pediatric hematologist and oncologist is often called upon to
distinguish between malignant versus benign masses, and vascular
anomalies should be on the differential of a new onset mass. Clinical
examination combined with imaging can generally lead to a diagnosis and
rule out malignancy. Experienced clinicians and radiologists familiar
with these entities are optimal. If unusual features are present on
physical exam or imaging, or if concerning clinical history is present,
biopsy must be considered. Caution must be taken with biopsy of vascular
lesions given their propensity to bleed.
Under ultrasound examination, VMs appear as heterogeneous lesions
typically containing anechoic vascular channels. The lesions are
compressible if near the skin surface. VMs demonstrate slow flow, and
Doppler analysis typically shows minimal to no color flow that can be
augmented upon releasing compression or with Valsalva maneuvers.
Spectral analysis reveals no waveforms or a monophasic venous waveform
(16,17). If Doppler does not demonstrate color flow and/or spectral
waveforms, flow within the malformation may be too slow for sonographic
detection, or vessels may have thrombosed (18). Slow blood flow
contributes to the development of phleboliths, which are painful
thrombosis and a common occurrence of VMs. On exam, they are palpated as
hardened nodules (19). On US, they appear as a hyperechoic foci with
posterior shadowing and are considered pathognomonic for VM (20).
As in this patient, on magnetic resonance imaging (MRI), VMs appear
hyperintense on T2 weighted images (Fig 2). On T1 weighted images, they
appear iso- or hypointense but may contain hyperintense areas
representing blood products, fat, or calcifications. VMs enhance on T1
weighted images obtained after intravenous contrast administration. MRI
not only aids in the classification of vascular malformations, but it
also can determine lesion extent and relationship to surrounding
structures (21,22).