Birthmarks are as unique as the people that have them. They can be any size and appear anywhere on the body, from the face to the feet. They might be bright red in appearance or hardly visible.
While most birthmarks are harmless, along with other types of skin lesions such as freckles and moles, they could carry a risk of developing into skin cancer.
As with all types of skin cancer, early detection is key when it comes to successful treatment. So, let us look at when to have birthmarks checked by a skin doctor and what to look out for in the meantime.
What are birthmarks?
It's not known exactly what causes a birthmark. Some can have a genetic factor, but this isn't always the case. They can appear anywhere on the body, in any shape, are often brown, black, blue, pink, white, purple or red, and can be raised above the surface of the skin or flat. They can last a lifetime, but sometimes they can fade with age.
These congenital marks are normally non-cancerous. However, some types of birthmarks, such as a giant congenital melanocytic nevus, carry a greater risk of turning into melanoma — particularly in childhood — so doctors recommend having birthmarks checked for skin cancer regularly.
What are the different types of birthmarks?
There are two categories of birthmarks: pigmented and red birthmarks.
Pigmented birthmarks are present at birth and range from brown to blue. They are caused by an overgrowth of the cells that create colour, or pigment, in the skin.
Red, or vascular birthmarks, can develop shortly after birth. They occur when blood vessels are wider than usual or when there are too many.
- Congenital melanocytosis: Usually blue-like bruises appearing on the buttocks, legs or arms.
- Café-au-lait spots: Light tan or brown and usually oval.
- Congenital nevi: A brown mole that is flat or raised.
- Macular stains: Often referred to as a stork bite, these faint red marks typically fade in 1–2 years. They are typically found on the forehead, lip, neck, nose or scalp.
- Hemangiomas: Can be superficial (strawberry marks), deep or compound, affecting both layers of skin.
- Port wine stains: Most often on the face, neck, arms or legs, they grow and darken as the child grows.
How to tell if a birthmark might be cancerous
There are three main types of skin cancer: squamous cell carcinoma, basal cell carcinoma and melanoma. Your risk of developing skin cancer depends on many factors, including your lifestyle and medical conditions. However, no matter the type of skin cancer, early prevention is a key factor in successful treatment. Therefore, it's important to keep an eye on any skin lesions, including birthmarks, to watch for signs of change that could indicate skin cancer.
The best way to do this is to know the ABCDEs of melanoma so you can perform a regular self-examination. You should also become familiar with the signs of skin cancer so that if you notice changes in a birthmark or if you have a new growth, you can have it examined.
You should also undergo regular skin checks with a doctor, particularly if you have other risk factors, which we will discuss below.
Skin cancer risk factors
Some risk factors that may make people more prone to skin cancer include:
- Having fair hair or a fair skin tone
- A personal or family history of skin cancer
- An atypical mole (dysplastic nevi) or many moles or freckles
- A history of sunburn or tanning bed use
Birthmarks with the strongest links to skin cancer
Specific types of birthmarks and moles have a greater association with the development of skin cancer. Most of these have unique features which can make spotting changes in them difficult. They include:
- Multiple or large congenital and acquired melanocytic naevi: A known risk factor for melanoma, particularly if greater than 20cm.
- Dysplastic nevi: Unusual-looking moles with irregular features. It is difficult to differentiate it from melanoma.
- Blue nevi: Difficult to differentiate from melanoma and carries the risk of metastasis if it becomes malignant.
- Nevus spilus: Light brown birthmark with small brown spots, speckles or lumps.
- Halo nevi: Lack of pigment around the mole makes it more prone to damage from ultraviolet light.
- Spitz nevi: Fast-growing moles linked to increased melanoma risk.
How to prevent skin cancer
As well as undergoing a birthmark and mole check with your doctor each year, there are preventative measures you can take each day to avoid skin cancer.
- Apply sunscreen daily
- Limit your exposure to UV radiation during the hottest parts of the day
- Wear sun-protective clothing, such as a hat and sunglasses
- Monitor and record information about birthmarks during a self-examination, such as the size, colour and feel
- Don't forget to check places such as the soles of your feet, palms and under your fingernails during a skin self-examination
Birthmark or skin cancer? Where to go for advice
Any skin lesion, including a birthmark, can change over time. Most people realise the importance of checking moles for signs of skin cancer, but keeping an eye on our birthmarks is just as important. This is because changes to the look, feel, or texture of our spots can indicate the development of skin cancer.
Skin cancer is harder to detect in some types of birthmarks than others due to their appearance, so you must follow up on any concerns with a doctor as soon as possible. The early detection of skin cancer saves lives.