Laser and Skin

Vascular lesions: an overview of red marks

Red and blue marks on the skin range from a harmless cherry angioma the size of a pinhead to a port wine stain that covers part of the face. Nearly all of them respond to a vascular laser: small spots often clear in 1 to 2 sessions, while a port wine stain typically needs 8 to 10. Because a few of these marks can point to an underlying condition, a doctor should look at any red mark before treatment starts.

The main types of red marks

A cherry angioma, also called a senile angioma, is a pinhead sized red dot that appears on the trunk from around age 40 and stays harmless for life. A spider naevus shows one central vessel with fine branches running out from it, forming a web that can reach up to a centimetre across, and can appear at any age. Both are cosmetic concerns rather than medical ones.

A port wine stain, medically a naevus flammeus, is a congenital malformation of widened capillaries visible from birth, most often on the face or neck. It grows in proportion to the child and, left untreated, often darkens and thickens into a cobblestone texture over 20 to 30 years, a pattern covered in the separate guide to port wine stain treatment. An infantile haemangioma, the classic strawberry mark, is different: it is rarely visible at birth, grows during the first 3 to 6 months of life, then fades by itself in about half of children by age 5 and in almost all by age 7, as the haemangioma guide sets out in more detail.

Couperose and thread veins, known medically as telangiectasia, sit in the same family but have different causes and their own separate guide, so this overview does not cover them in depth.

Why light works so well on these vessels

All of these marks share one feature: they are full of blood, and blood absorbs light of certain wavelengths strongly. A pulsed dye laser sends a wavelength of about 585 to 595 nanometres into the skin, where the red pigment inside the vessel takes up the energy in a fraction of a second. The vessel wall overheats, seals shut, and the body clears the debris over the following weeks, while the skin around it barely absorbs the same wavelength and stays largely undamaged.

This is why the group is one of the most reliable targets in laser medicine. Small angiomas often clear in 1 to 2 sessions, a spider naevus frequently needs just 1, but a port wine stain commonly takes 8 to 10 sessions spaced 4 to 8 weeks apart, and full clearance is never guaranteed. Facial marks generally respond faster than the same mark on an arm or leg, and an older, thicker stain resists treatment more than a fresh, flat one.

In several countries this work is reserved for doctors. In Germany, for example, a regulation on non ionising radiation has named the treatment of vascular skin lesions a medical procedure since the end of 2020, and professional bodies for dermatology in the UK set similar training expectations for anyone using a vascular laser.

When a red mark is more than a cosmetic question

3 situations move the question from a wish to a need. A facial port wine stain, especially one that touches the eyelid or forehead, can in rare cases sit alongside other malformations, so an eye check and sometimes further imaging are the right next step rather than a wait. An infantile haemangioma growing near the eye, nose, mouth or nappy area needs an early opinion too, because it can interfere with sight, breathing or feeding within the first 3 months of life. And any mark, at any age, that suddenly bleeds, grows or changes shape belongs in front of a doctor within days, not months.

Outside these 3 situations, a first consultation is simply the sensible starting point, and most people decide from there whether to treat a harmless mark at all.

What happens inside the vessel during treatment

The wavelength is absorbed by the red pigment in blood almost the instant the pulse fires. The blood inside the vessel heats sharply, passes that heat to the vessel wall, and the wall collapses shut. From that point the vessel is sealed, blood reroutes through neighbouring capillaries, and the body reabsorbs the closed structure over the following 4 to 8 weeks.

Because the surrounding tissue barely takes up the same wavelength, it stays largely untouched. What you see straight after a session is often a bluish mark called purpura, caused by the treated vessel itself. Purpura is expected, not a complication: it affects up to 10% of patients according to published treatment data, and normally fades within 7 to 14 days.

Some marks need far more sessions than others simply because of size and depth. A cherry angioma has 1 vessel to close. A port wine stain is a dense network of hundreds of tiny vessels across several square centimetres of skin, which is why 1 appointment clears one and 10 barely finish the other.

Before and after your appointment

Blood thinning medication is worth mentioning to your doctor before the first session, because it raises the chance of bruising, and nothing should be stopped without medical advice. Tanned skin is unfavourable for this treatment, since melanin competes with blood for the same wavelength, so most clinics prefer the low sun months, roughly October to March in the northern hemisphere, for a course of sessions.

Afterwards, cooling the area for the first 24 to 48 hours helps with swelling, and the spot is best left alone for a few days. Sport that raises circulation, saunas and hot baths are unhelpful for 48 hours because they increase pressure in the treated vessels. Sun protection, ideally factor 30 or higher, matters for 4 to 6 weeks after each session.

A fair judgement of the result needs at least 4 weeks, because reabsorption of the closed vessel takes that long. Anyone who checks after 1 week is really looking at the purpura, not the outcome, and a full course for a stubborn mark can span 12 months or more between sessions.

Questions to ask before you book

Frequently asked

Are small red dots on the trunk dangerous?

A cherry angioma appearing from age 40 onward is harmless. Any mark that changes, bleeds or grows should be examined by a doctor.

Does a port wine stain fade on its own?

No, it is a congenital malformation of widened blood vessels that grows with the child and can darken over the years. An infantile haemangioma is different, since it often fades by itself over several years.

Why does laser treatment work so well on red marks?

Blood absorbs light of specific wavelengths strongly, so the vessel heats from within and seals shut, while the surrounding skin barely absorbs the same wavelength.

Who is allowed to treat vascular lesions?

In most countries this work sits with doctors or dermatologists who have specific laser training. Germany's non ionising radiation regulation, for example, has named these treatments a medical procedure since the end of 2020.

When should I act quickly rather than wait?

For a facial port wine stain near the eyelid or forehead, for an infantile haemangioma near the eye, nose, mouth or nappy area, and for any mark that suddenly bleeds or grows.

What is the bluish mark after a session?

It is called purpura, comes from the treated vessel itself, and is expected rather than a problem. It normally fades within 7 to 14 days.

Sources

• Birthmarks · types of birthmark, when they fade, and when laser treatment is offered
• Port wine stain · NIH MedlinePlus, progression, associated syndromes, laser response by site
• Hemangioma · NIH MedlinePlus, growth pattern and spontaneous resolution by age
• Pulsed dye laser treatment · DermNet NZ, wavelength, mechanism, session counts and purpura rate

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This guide is for general information. It does not replace medical or professional cosmetic advice or an examination.