The Bottom Line
Venous malformations are birthmarks made of abnormally formed veins. They look blue or purple, feel soft and squishy, and — unlike strawberry hemangiomas — do not go away on their own. They can affect any part of the body, including areas where they press on nearby structures and cause problems. Treatment depends on the size, location, and whether the malformation is causing symptoms. Many small, asymptomatic venous malformations can simply be watched. When treatment is needed, sclerotherapy (injections to shrink the veins) and surgery are the main options.
What Is a Venous Malformation?
A venous malformation is a type of vascular birthmark — a structural abnormality in blood vessels that forms while a baby is developing in the womb. Specifically, venous malformations involve channels made of improperly formed veins: the vessel walls are thin, weak, and prone to pooling blood instead of circulating it normally.
Unlike infantile hemangiomas (the classic "strawberry" birthmarks), venous malformations are present from birth — even if they aren't immediately noticed — and they do not go through a growth and shrinkage cycle. They tend to slowly enlarge over years, particularly during puberty, pregnancy, or times of hormonal change.
What Does a Venous Malformation Look Like?
Venous malformations have a distinctive appearance and feel:
- Color: Blue or blue-purple, because the pooled venous blood (which is darker than arterial blood) shows through the skin
- Feel: Soft and compressible — if you gently press on it, it deflates slightly as blood is pushed out, then refills when you release pressure
- Temperature: Not warm to the touch (unlike hemangiomas, which can feel warm)
- Position: Color and size may temporarily worsen when the area is in a dependent position (lower than the heart) or after exercise, due to blood pooling with gravity
- Texture: Sometimes described as a "bag of worms" texture if multiple enlarged channels are present close together
They can appear anywhere on the body — face, lips, tongue, neck, limbs, or within deeper tissues — and range from small spots to large lesions involving multiple tissue layers.
How Is a Venous Malformation Different from a Hemangioma?
This is one of the most common questions parents have, because both can look bluish and soft. The distinction is important because the two conditions behave differently and need different treatment:
| Feature | Venous Malformation | Infantile Hemangioma |
|---|---|---|
| Present at birth | Yes (may not be obvious) | Appears weeks after birth |
| Growth pattern | Slowly enlarges, never shrinks | Grows rapidly then involutes |
| Goes away on its own | No | Usually yes (by age 7–10) |
| Responds to propranolol | No | Yes |
| Feel | Soft, squishy, compressible | Firmer, rubbery |
If you're unsure which type of vascular birthmark your child has, a dermatologist with experience in vascular anomalies can usually tell you quickly — often just by examination, sometimes with the help of an ultrasound.
What Complications Can Occur?
Many venous malformations cause no problems and just need periodic monitoring. But depending on their size and location, complications can develop:
- Thrombosis (clotting within the malformation): Blood pooling inside the malformation can clot, causing sudden, painful enlargement. This is the most common complication and is often triggered by trauma, illness, or hormonal changes. The area may become firm, tender, and bruised-looking.
- Bleeding: Venous malformations in the mouth, throat, or digestive tract can bleed, sometimes significantly.
- Compression: Malformations near the airway, eye, or a joint can cause functional problems — breathing difficulties, vision changes, or limited movement.
- Cosmetic disfigurement: Visible malformations, especially on the face or hands, can cause significant emotional distress for children and teenagers.
- Coagulopathy: Large venous malformations can chronically consume clotting factors, leading to a bleeding tendency called Kasabach-Merritt phenomenon (more commonly associated with other vascular tumors) or localized intravascular coagulation.
How Are Venous Malformations Diagnosed?
Diagnosis starts with a physical exam. The soft, compressible, bluish appearance is usually sufficient to make a clinical diagnosis. Imaging helps determine the extent:
- MRI: The best imaging tool for venous malformations. Shows the full extent of the malformation, including deep involvement not visible on the surface. Venous malformations appear bright on T2-weighted MRI sequences.
- Ultrasound: Useful for quick bedside assessment of compressibility and blood flow patterns
- CT scan or angiography: Used in select cases to plan treatment
Treatment Options
Not all venous malformations need treatment. The decision depends on symptoms, size, location, and impact on daily life.
- Observation (watchful waiting): For small, asymptomatic lesions that aren't growing or causing problems, regular monitoring is appropriate. No active treatment is needed.
- Compression garments: For malformations on a limb, elastic compression can reduce blood pooling, decrease swelling, and lower the risk of thrombosis.
- Sclerotherapy: The most common active treatment. A doctor injects a chemical agent (such as ethanol, sodium tetradecyl sulfate, or bleomycin) directly into the malformation under imaging guidance. The agent irritates the vessel walls, causing them to scar down and shrink. Multiple sessions are often needed, and results vary by lesion characteristics.
- Surgical excision: Removal of the malformation surgically. Complete removal isn't always possible for large or deep lesions, but partial removal or debulking can reduce symptoms. Often combined with sclerotherapy.
- Thrombosis management: If thrombosis causes acute pain and swelling, anti-inflammatory medications and supportive care can help. Anticoagulants may be used in some situations.
- Emerging medical therapies: Drugs targeting the PI3K/mTOR pathway (such as sirolimus) are being studied for venous malformations and have shown promise in reducing lesion size and symptoms in some patients.
When to See a Dermatologist or Vascular Specialist
- Your child has a soft, blue or purple area on the skin that was present at birth or appeared in early childhood
- A known venous malformation is growing or causing pain
- Sudden painful enlargement occurs — this may be thrombosis and warrants prompt evaluation
- The malformation is near the eye, mouth, airway, or a joint — these locations need specialist attention
- Your child is emotionally distressed by a visible malformation and you want to discuss cosmetic treatment options
Frequently Asked Questions
Will my child's venous malformation get bigger over time?
Venous malformations do not spontaneously resolve, and many slowly enlarge over years. Growth is often most noticeable during puberty and pregnancy. However, many small lesions remain stable for long periods. Regular monitoring with a specialist allows for early intervention if growth or symptoms develop.
Is sclerotherapy safe for children?
Yes, when performed by an experienced interventional radiologist or vascular specialist. Like any procedure, it carries risks including skin injury, swelling, and — rarely — damage to nearby nerves or tissues. The risks and benefits should be discussed carefully based on your child's specific lesion. General anesthesia is typically used for younger children.
My child's blue birthmark suddenly became painful and swollen — what happened?
This sounds like thrombosis (clotting) within the malformation — a common complication. The area becomes firm, tender, and may turn darker. This is painful but usually not dangerous in smaller lesions. Contact your child's doctor or specialist promptly. Anti-inflammatory medication and warm compresses can help, and your doctor will assess whether further intervention is needed.
Could this be something more serious than a venous malformation?
In rare cases, vascular anomalies that look like venous malformations can be associated with overgrowth syndromes or other complex conditions. An experienced specialist will look for additional features that would warrant further evaluation. For most isolated, soft, blue birthmarks in otherwise healthy children, the diagnosis is straightforward.
- Mulliken JB, Glowacki J. Hemangiomas and vascular malformations in infants and children: a classification based on endothelial characteristics. Plast Reconstr Surg. 1982;69(3):412–422.
- Dompmartin A, et al. Venous malformations: update on aetiopathogenesis, diagnosis, and management. Phlebology. 2010;25(5):224–235.
- Garzon MC, et al. Vascular malformations — Part II. J Am Acad Dermatol. 2007;56(4):541–564.
- Adams DM, et al. Efficacy and safety of sirolimus in the treatment of complicated vascular anomalies. Pediatrics. 2016;137(2):e20153257.
Trusted Resources
Always consult a board-certified dermatologist or specialist in vascular anomalies for personalized advice about your child's venous malformation.