Birthmarks

A birthmark is a mark on the skin that is either present at birth or develops in the first few weeks of life. Birthmarks are very common and most types do not require any treatment at all. This information sheet from Great Ormond Street Hospital (GOSH) describes the different types of birthmark that can occur, how they can be treated (if needed) and where to get help.

There are many types of birthmark, depending on the main cell type involved. Pigmented and vascular birthmarks are common.

Most pigmented birthmarks consist of cells containing melanin (pigment) collected together in one area producing skin that is a different colour to the rest of the body. These birthmarks can be a brown or black colour – they vary in size and severity. Pigmented birthmarks can sometimes be associated with other developmental changes.

Vascular birthmarks consist of vessels that have not formed properly. They can look a reddish or bluish colour, depending on their depth in the skin. Vascular birthmarks can very occasionally be associated with other developmental changes.

The Birthmark Unit at GOSH specialises in diagnosing and treating rare and/or complex birthmarks and vascular malformations including:

• Arteriovenous malformations 
• Blue rubber bleb naevus 
• Congenital haemangiomas 
• Generalised lymphatic anomaly 
• Glomuvenous malformations 
• Haemangiomas 
• Haemangiomatosis 
• Kaposiform haemangioendothelioma 
• Kasabach-Merritt phenomenon 
• Klippel-Trenaunay syndrome 
• Lymphatic malformations 
• Mongolian blue spot 
• PHACES syndrome 
• PIK3CA-related overgrowth syndromes and vascular anomalies
• Port wine stains 
• Sturge-Weber syndrome 
• Tufted angioma 
• Venous malformations 
• Verrucous venous malformations 

Many birthmarks arise from a change in a gene in the baby early in pregnancy when the skin and blood vessels are forming.

Marks on the skin may be immediately obvious after birth or may develop later.

Most birthmarks have a characteristic appearance so no specific diagnostic tests are needed. However, some birthmarks require imaging scans, especially if they might involve areas other than the skin. Ultrasound or MRI scans are the most commonly used types of imaging. Occasionally, a skin biopsy – a tiny sample of skin – needs to be taken for examination under a microscope to look for a change in a gene.

Most birthmarks do not require any treatment at all because they do not cause any problems. Others need more regular monitoring and sometimes benefit from treatment.

Haemangiomas, particularly if they are located where they could cause problems as they grow, such as by the eyes, nose or mouth, might require treatment. This is usually using medicines such as propranolol or timolol. Laser treatment can also reduce the colour of some red birthmarks such as port wine stains. Laser treatment uses a narrow beam of light that is absorbed by the red colour in the blood vessels in the port wine stain. This is called selective photothermolysis, which means that the specific area (selective) of tissue containing blood vessels is treated (lysis) using light (photo) that in turn produces heat (thermo).

Some types of birthmarks are present for life whereas others resolve. Some children are self-conscious of their birthmark as they grow older so may benefit from psychological input. The vast majority of uncomplicated birthmarks do not require treatment.