Classification and ultrasound findings of vascular anomalies in pediatric age: the essential

Infantile hemangioma
Infantile hemangioma is the most common vascular tumor 
in children up to 1 year old [
9
]. Diagnosis is generally clini-
cal, and ultrasound examination is often unnecessary. In any 
case, US may be required for extensive and deep lesions and 
during pharmacological follow-up [
7
, 
9
, 
10
].
It should be noted that this lesion has a characteristic 
clinical history. Mass is never present at birth, but there 
may be flat prodromal signs on the skin that subsequently 
increase in volume during the proliferative phase of heman-
gioma [
9
]. Infantile hemangioma, in fact, characteristically 
has two phases: a 
proliferative phase
, in which it appears 
in the first days/weeks of life and grows rapidly for sev-
eral months (Fig. 
1
), and an 
involutive pha
se, lasting up to 
age 8–9 years, in which there is a progressive reduction in 
volume with an increase in adipose tissue compared to the 
vascular tissue [
7
, 
11
–
13
].
• 
The US aspect of hemangioma also depends on the phase 
in which it is examined. In the 
proliferative phase
, the 
hemangioma is generally a well-defined mass with a non-
homogeneous echostructure and may be predominantly 
hyperechoic, hypoechoic, or with a lobulated appearance 
(Fig. 
2
). Of these patterns, it is difficult to say which is 
the prevailing one, and the results in the literature are 
rather discordant. In some cases, the hyperechoic aspect 
prevails [
9
], while in others the hypoechoic aspect pre-
vails [
14
]. At the color Doppler (ECD) exam, infantile 
hemangioma appears richly vascularized with high vas-
cular density and uniform vessel distribution within the 
lesion [
7
, 
9
, 
13
, 
15
] (Fig. 
3
). Regarding vascular density, 
some authors have determined the vascular density in 
relation to the number of vessels per square centimeter, 
classifying as highly vascularized lesions with more than 
five vessels per square centimeter [
16
]. However, this 
quantitative approach is not very significant at present 
due to the enormous improvement of modern ultrasound 
devices (Fig. 
4
) and is not very useful from the practi-
cal point of view, presupposing a technical uniformity 
of examination usually not obtainable. Spectral analysis 
detects prevalent presence of arterial flows that show 
low resistance and relatively high velocities [
7
, 
17
–
19
]