Infantile Hemangioma vs Vascular Malformation: Doppler Differential Diagnosis According to ISSVA
Classification of Vascular Anomalies (ISSVA)
Two main types of vascular anomalies are identified: vascular tumors and vascular malformations. Vascular tumors include infantile hemangioma (manifests after birth; cycle: proliferation → stabilization → involution) and congenital hemangioma (present at birth, including rapidly involuting forms). Infantile hemangioma is a benign vascular tumor composed of proliferating endothelial cells, not a malformation.
Ultrasound Appearance of Infantile Hemangioma
Infantile hemangioma is described as a solid, usually hyperechoic lesion with lobulation and sometimes visible intalesional vessels. On color Doppler, typically high vessel density with low-velocity (low-flow) flow characteristics, with high-velocity pattern encountered less frequently. According to another source, mixed hyper- and hypoechoic lesion with few or absent visible vessels but with augmented flow on color or power Doppler. Histologically: small vessels with increased stromal component. As involution progresses, the lesion acquires indistinct margins and less pronounced vascularity.
Ultrasound Appearance of Vascular Malformations
Intramuscular vascular malformations have a heterogeneous appearance with variable echogenicity (ranging from hypo- to iso- and hyperechoic) and often infiltrate soft tissues. Typical anechoic or hypoechoic channels with flow on color/power Doppler are characteristic; flow can be very slow and difficult to distinguish without augmentation by manual compression.
Venous malformation appears very similar to hemangioma: slow or absent flow on color Doppler, while arterial supply is expected; presence of 1–2 arteries does not indicate a high-velocity lesion. Venous vascular malformation (VVM) is represented by sinusoidal spaces with reduced stromal component; phleboliths may be detected (more often in slow-flow lesions). Slow flow is often better visualized on grayscale imaging as to-and-fro movement of echosignals within the contents.
Key Doppler Differential Features
| Feature | Infantile Hemangioma | Vascular (Venous) Malformation |
|---|---|---|
| Echo structure | Solid, usually hyperechoic, ± lobulation | Heterogeneous, anechoic/hypoechoic channels or cystic spaces |
| Vessel density | Usually high | Variable; stroma with reduced vascular component |
| Flow character | Low-velocity (less often high-velocity) | Slow or absent flow on color Doppler |
| Phleboliths | [to be clarified] | May be detected, more often with slow flow (VVM) |
| Slow flow | Color/Power Doppler assessment | Better visualized on grayscale as to-and-fro movement of contents |
Methodology of Doppler Assessment
Vascularity is assessed in grayscale, color, and power Doppler modes. Grayscale is useful for evaluating slow venous flow; color Doppler determines flow direction but is less sensitive than power Doppler; power Doppler does not assess direction; spectral analysis analyzes flow pattern. Minimal probe pressure should be used to avoid vessel compression. The predominance of central or peripheral vascularity pattern, organized or chaotic, or mixed pattern should be noted.
For all vascular anomalies, the following are determined: size and location, predominant vascular type (arterial/venous/capillary), ratio of vascular to stromal tissue, presence of thrombi or phleboliths, flow characteristics, and multiplicity of lesions.
Arteriovenous Malformation
AVM consists predominantly of dilated vascular channels with relatively small stromal volume; pulsation may be visible on grayscale, and color Doppler reveals predominantly arterial channels, indicating a high-velocity lesion rather than hemangioma. Hemangiomas typically do not have such high blood flow. MRA is superior to ultrasound or MRI in detecting the nidus, feeding artery, and draining vein of AVM.
Limitations of the Method
Ultrasound findings vary considerably; however, in most cases vascular anomaly can be reliably diagnosed on ultrasound. Diagnosis is based on a combination of features rather than one or two alone. Differentiation of hemangioma and vascular malformation by imaging alone is difficult. The stromal component often contains vessels too small for resolution on ultrasound; contrast-enhanced CT/MRI is preferred to clarify extent and anatomy.
Frequently asked questions
How to distinguish infantile hemangioma from venous malformation on Doppler?
Hemangioma is a solid hyperechoic lesion with high vessel density and low-velocity flow; venous malformation appears very similar but shows slow or absent flow on color Doppler with expected arterial supply. Differentiation by imaging alone is difficult and relies on a combination of features.
Why may blood flow not be detected in malformation?
Flow can be very slow. It can be detected by augmenting flow with manual compression or by assessing to-and-fro movement of echosignals on grayscale imaging.
What indicates high-velocity AVM rather than hemangioma?
Dilated vascular channels with small stromal volume, visible pulsation on grayscale, and predominantly arterial channels on color Doppler. Hemangiomas typically do not have such high blood flow.
Which Doppler mode is more sensitive for slow flow?
Power Doppler is more sensitive than color Doppler in detecting flow, but does not assess direction. Grayscale is useful for slow venous flow; color Doppler assesses direction, and spectral analysis evaluates flow pattern.
What does the presence of phleboliths indicate?
Phleboliths are more common in slow-flow lesions, such as venous malformation, and may cause acoustic shadowing.