Common Types Of Moles And Their Risk Of Skin Cancer

About 2000 Australians die from skin cancer each year, and more than two in three Australians will be diagnosed with skin cancer in their lifetime, according to the Victorian website SunSmart. That’s why it’s essential to be sun safe, and also be on the lookout for any moles that could potentially be cancerous.

What are moles?

Moles (naevus) are a cluster of melanocytes – cells that give colour to our skin. They are extremely common, with most people having between 10 and 40 moles. Most moles are harmless, but some can turn into melanomas. Below, we list the common types of moles, highlight those that warrant further inspection and discuss mole removal methods.

Remember: Early skin cancer detection gives you a better chance of avoiding surgery, or in serious cases, potential disfigurement or even death.

What are the different types of moles?

Congenital moles

A congenital mole is either present at birth or appears by two years of age. Congenital moles are also called ‘birthmarks’. These moles can be the same size as other moles. Occasionally, they are much larger, more than 20 cm in diameter, and are called giant naevi. There is a risk of melanoma in giant naevi, which is directly related to the size of the mole, so they must be monitored carefully with regular skin cancer checks.

Congenital moles can be single or multi-coloured. They are round or oval-shaped and can be hairy

Freckles

Freckles are small spots on the skin that most commonly appear on sun-exposed areas. They are clusters of melanised cells and can range in colour from red to brown. Freckles appear during childhood, with more appearing until early adulthood. Fair people and those with red hair most commonly have freckles. Those with darker skin have freckles that appear as dark spots.

Seborrheic Keratoses

Seborrheic keratoses are the most common benign lesions that mimic the look of melanomas. They are raised, benign growths of keratinocytes (the outer layer of skin cells) that appear in the epidermis (upper layers of skin). Seborrheic keratoses are often pigmented, giving them a dark, mole-like appearance, and can be easily mistaken for warts or melanoma. They can be tan-coloured to dark brown, have a waxy appearance and are usually rough to touch. You can find them on covered or sun-exposed areas.

Spitz naevi

Spitz naevi can look very similar to melanoma. They typically appear as a pink, raised bump. However, they can also be blue, red, dark brown or black – or have no pigment. Spitz naevi usually appear on the face, neck and legs but can appear on the shoulders, arms or torso. They are most common in children and teens. These lesions grow quickly and can grow up to 1 cm in diameter in as little as six months. They then maintain their size for a few years before gradually becoming smaller or disappearing altogether.

Blue naevi

A blue naevus (mole) is typically blue, but can be grey, brown or cream. It is uniform in colour with no pattern. Due to its dark colour, it can often be mistaken for a melanoma. They can be present at birth or appear later in life. They are typically flat or dome-shaped with a smooth surface. Blue naevi are usually 0.5 to 1 cm in size. These naevi can appear on the head, neck, sacral area, feet or backs of hands, but can be found on other body areas.

Halo naevi

Halo naevi are moles surrounded by a white or pale area, or ‘halo’. This pale area persists around a normal mole for several years before gradually disappearing. As irregular halos are present around some melanomas, an appropriately qualified doctor should inspect all new or changing halo naevi.

Acquired naevi

Acquired naevi are new moles that appear on the skin spontaneously in children or young adults. Typically, the individual is under 40, but they can appear in later years. These moles are genetically determined, and people with numerous moles often have parents with numerous moles.

Dermal naevi

A dermal naevus (intradermal mole) is a benign, well-defined, raised mole that is typically soft. They can be the same colour or darker than the skin, with or without hair. These moles usually appear on the face, especially around the nose.

Dysplastic naevi

Dysplastic naevi (aka atypical moles, Clark naevi) are often multi-coloured, irregularly shaped and have an unclear border. They may look different to other moles on the skin. These naevi appear similar to melanomas, so they are often surgically excised to rule out any cancers. While these moles are harmless, individuals with multiple dysplastic naevi are at a higher risk of developing melanoma.

Lentigo

Lentigo (age spots or liver spots) are a type of freckle, not a mole. They are caused by repeated sun exposure over many years and commonly appear in ageing skin. Lentigines can be removed with IPL or laser, if desired. Typically, lentigines do not change size or shape, but change in colour, becoming darker or lighter in keeping with levels of sun exposure.

What causes moles to form?

Moles are a common type of skin growth. They are formed from little clusters of skin cells called melanocytes. These cells produce melanin, the natural pigment that colours your skin. Melanocytes usually distribute evenly throughout the skin. When they grow in groups, they form small, dark marks, or sometimes flesh-coloured small bumps on your skin.

What is the difference between cancerous and benign moles?

It takes a trained eye to differentiate between a cancerous and a benign mole. However, certain features differentiate a cancerous from a benign mole. You can recall these features by remembering ‘A, B, C, D, E’.

• ASYMMETRY: Moles are symmetrical or uniform in shape, whereas melanomas may have an asymmetrical shape.
• BORDERS: Moles typically have an even, well-defined border separating them from the surrounding skin. They can be raised or flat. However, melanomas have an irregular or poorly defined border that blends into the surrounding skin. A melanoma border may be blurred, notched or uneven.
• COLOURING: Moles are usually one colour, such as brown, black or skin coloured. Melanomas can have an unusual colouring or variation in colour.
• DIAMETER: Moles are typically small (under 6 mm). They are considered harmless unless they change their size or appearance over time.
• EVOLUTION: Moles typically stay the same size, shape, texture and colour. Alternatively, melanomas can change in appearance over time. For example, a mole or spot may grow larger, change colour or shape, become raised or bumpy, or develop new symptoms such as itching, crusting or bleeding. An appropriately qualified medical professional should examine any such changes.

How can moles be removed?

Moles can be removed in various ways, depending on their position, size and whether they’re suspected to be cancerous. However, any mole suspected of being a melanoma must be surgically removed.

Nonsurgical mole removal treatments include:

IPL and laser: Suited to remove flat pigmented moles like age spots, freckles, or lesions of blood vessels such as telangiectasia or angiomas. IPL or laser mostly leaves no scars and may not even break the skin.

Cryotherapy: Involves freezing a mole with liquid nitrogen. Suits many different types of skin lesions, including skin tags, solar keratoses and seborrheic keratoses. In certain instances, even superficial skin cancers can be treated. Scarring or blistering may occur, and some moles may require multiple treatments.

Electrosurgery: Involves burning off the skin lesions using electric current. Suitable for lesions such as some raised moles, solar keratoses, seborrheic keratosis, angiomas and skin tags. This treatment usually requires anaesthetic as it can be painful. As it burns the skin, there is a risk of scarring.

Radiofrequency surgery: Also known as radiosurgery, it heats unwanted skin lesions with high-frequency radio waves. This treatment is similar to electrosurgery but has less heat and less damage to surrounding tissues (with less risk of scarring). Suitable for treating angiomas, seborrhoeic keratoses and raised moles.

Shaving: A surgical blade can be used to carefully shave the mole of the skin’s surface. This method only removes the top layer of the mole.

Surgical mole removal

Surgical excision: The area is thoroughly cleaned and numbed with anaesthetic (either topically, by injection, or both). The surgeon uses a scalpel to separate the mole from the rest of the skin. Depending on the type of mole, the surgeon may take a margin of healthy skin to ensure that all of the atypical cells are removed. The mole is then removed by forceps, and, if required, the skin is stitched back together. Typically, the mole is sent to a laboratory for testing.

Mole FAQ

Do moles hurt?

Most of us have between 10 and 40 moles, with most not causing problems or pain. Occasionally, a pimple may develop underneath the mole. As the mole stops the pimple from rising to the surface, it may become sore until it slowly disappears. Similarly, a hairy mole may develop an ingrown hair that can become irritated, inflamed and painful until it heals. If the mole is scratched or continually rubbed, it can also become inflamed, causing pain. Notably, most cancerous moles do not cause pain; however, some melanomas can cause pain and soreness.

Should a mole itch?

Most — but not all —moles are harmless—even if they itch. It’s recommended that any itchy mole be checked (particularly if any other changes accompany it) as it can occasionally be a sign of skin cancer, including melanoma.

Is it normal for a mole to bleed?

A mole that bleeds for no reason can be a sign of skin cancer (particularly if it is accompanied by itching), so it must always be checked by a doctor. However, moles can also bleed because they have been scratched or torn. Although an injured and bleeding mole may be painful, it is usually not a cause for concern.

What is the difference between a pigmented lesion and a mole?

A mole is a pigmented lesion. However, a ‘pigmented lesion’ is a generic term encompassing freckles, age spots (lentigines) and normal moles.

References:

Health Direct: Moles

https://www.healthdirect.gov.au/moles

Sunsmart: skin Cancer FAQs & stats

https://www.sunsmart.com.au/skin-cancer/skin-cancer-facts-stats