Moles: Types, causes, treatment, and diagnosis

Moles are small lesions in the skin. They are a collection of melanocytes. Melanocytes are melanin-producing cells. Melanin is a pigment which gives skin its color.

Moles are usually brownish, but some may be much darker, while others are skin-colored. They can be rough, flat, raised, and have hair growing out of them. They are generally round or oval, and have a smooth edge.

Moles can change in appearance and amount. Sometimes they eventually fade away or drop off. Some moles respond to changes in hormone levels, as may occur during pregnancy, adolescence, and older age. During teen years they usually grow in number, they also get darker during pregnancy and gradually fade away as people age.

The majority of moles appear during the first 20-30 years of a person’s life, however, some may be present when the baby is born. Congenital melanocytic nevi are present at birth, any moles appearing after birth are melanocytic nevi. Dark skinned people generally have fewer moles than those with fair skin.

Fast facts on moles

Most moles are inherited.

People brought up in sunny places tend to have more moles than others with the same type of skin who were raised in areas with comparatively little sun exposure.

Sun spots, which may be caused by severe sunburn, are not moles.

The vast majority of moles are harmless. In rare cases they can develop into an aggressive type of skin cancer called malignant melanoma.

If you have moles, you should check them regularly for changes in texture and appearance.

Common types

A round flat junctional mole. Image credit: Unknown photographer, National Cancer Institute, 1985
Junctional moles are round flat.
Image credit: Unknown photographer, National Cancer Institute, 1985

Junctional melanocytic nevi

These are usually:

usually round

flat

brown

It is called ‘junctional’ because it is at the junction of layers of the skin dermis and epidermis layers.

A dermal nevus is raised and may have hair. Image credit: Unknown photographer, National Cancer Institute, 1985
A dermal nevus is raised and may have hair.
Image credit: Unknown photographer, National Cancer Institute, 1985

Dermal melanocytic nevi

These have the following characteristics:

usually raised

sometimes hair

skin colored or light brown

It is the kind of mole that is eruptive, meaning it sticks out of the skin.

A mole with a white ring around it. Image credit: Leonard C. Sperling, M.D., COL, MC, USA, 2009
A halo nevus has a white rind around it.
Image credit: Leonard C. Sperling, M.D., COL, MC, USA, 2009

Halo nevi

The skin around it has lost its color, so it has a white ring around it

The ring is what gives this type of mole its name name.

When the mole eventually fades away, the skin regains its color.

Image credit: Unknown photographer, National Cancer Institute, 1985

Image credit: Unknown photographer, National Cancer Institute, 1985

Dysplastic nevi

Also known as atypical nevi or Clark nevi. These can be:

flat or bumpy

large

irregular on the edges

These do not change over time and are an unusual looking mole.

Older people tend to have seborrheic keratoses. These are not moles; they may look like them, but they are blemishes. They look like raised warts. They can be gray, brown, yellowish, or black. They are more commonly found on the tummy and chest.

Freckles are not moles.

Treatment

The majority of moles are harmless and require no treatment. They may be surgically removed if:

The mole is a suspected melanoma.

It is bothersome, such as if the patient finds shaving difficult, or it gets snagged in clothing.

A mole may be removed in several ways:

Shave excision – the area around the mole is numbed, a small blade is used to cut around and under the mole. A technique commonly used for smaller moles. No sutures (stitches) are needed.

Excisional surgery (excision biopsy) – the mole plus a surrounding margin of healthy skin is cut out using a scalpel or a punch device. Sutures are required.

If the melanoma is detected in the very early stages, when the mole is thin and has not grown downwards from the surface of the skin and spread to other parts of the body, it is removed using a simple surgical technique.

If it is detected in later stages, it will be removed, plus some healthy skin around it – called a safety margin. If the cancer has entered the bloodstream or lymphatic system and formed tumors in other parts of the body, the patient will require further treatment.

A normal mole
An example of what was considered a normal mole. In this case the edges were deemed to be even, not ragged and not notched. Part of the ABCDs for detection of melanoma. Source: National Cancer Institute

In general, moles are brown; however, they can come in a variety of sizes, shapes and colors:

Shape – they can be oval and round.

Color – they are usually medium-to dark brown, reddish brown, or flesh colored.

Size – moles can vary enormously in size. They can cover an entire arm, or be as small as a pinhead. Typically, they are less than 6 millimeters (1/4 inch) long.

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