What is a benign mole?
Most moles are benign or harmless. A mole is a type of skin growth or lesion, commonly referred to as a nevus (plural: nevi). Nevus is a generalised medical term for a visible, circumscribed, chronic lesion which sits on the skin or mucosa. Nevi can take the form of freckles, moles, skin tags and seborrheic keratoses.
Typically, moles are pink, brown or tan in color with a distinct border. Moles usually develop within the thick layer of living tissue below the epidermis (outer layer of skin), which contains blood capillaries, nerve endings, sweat glands, hair follicles, and other structures. Moles occur when cells in the skin grow in a cluster instead of being spread throughout the skin.
Some moles develop from cells are called melanocytes, which make the pigment that gives skin its natural color. Moles can also develop from other cells, including nevus cells.
Causes of benign moles
Moles can occur anywhere on the body. Moles can be present at birth, but it is possible for them to develop throughout one’s lifetime. People of all ages can be born with moles, or develop new moles of any size and color. In general, however, darker skin types usually have darker moles.
Most moles are made of cells called melanocytes which make a pigment called melanin. Melanin has two principal functions: it helps to protect the body from ultraviolet light (UV radiation) from the sun and gives skin and hair its natural color. People with darker complexions have more melanocytes, and are more likely to develop new moles after exposure to sunlight.
Common types of benign moles
- Compound melanocytic nevi: These are usually raised above the skin, light brown and sometimes hairy.
- Dermal melanocytic nevi: These are usually raised, pale and sometimes hairy.
- Junctional melanocytic nevi: These are usually brown, round and flat.
A seborrheic keratosis is a kind of skin growth which usually appears as a brown, black or light tan growth on the face, chest, shoulders or back. They are common, and can be scaly, waxy and slightly raised above the skin (elevated). Although they are harmless, they can be difficult to distinguish from melanoma, one of the most serious types of skin cancer, so it is advisable to have them checked.
Atypical types of benign mole
Atypical moles are unusual-looking benign moles. They are also known as “dysplastic nevi.” Atypical moles may be mistaken for melanoma. Even though an individual atypical mole may be benign, people who have them are at increased risk of developing melanoma in a mole or elsewhere on the body.
- Blue nevi: these are dark blue in color and can be flat or raised.
- Dysplastic or atypical nevi: these are also known as “Clark nevi” and are unusual looking, slightly larger moles with irregular borders.
- Halo nevi: these are benign moles surrounded by a white ring where the skin has lost its color.
Changes in benign moles
The appearance of a benign mole can change over time. Moles can change in number and appearance and can also fade away over time. It is important to familiarise oneself with the moles on one’s body so as to establish the size, shape and type of moles that are normal, as this is different for each individual.
Environmental factors such as exposure to sunlight, and hormonal changes such as going through puberty or pregnancy can cause moles to darken or develop. Changes in moles may require a visit to a doctor to determine if the mole is exhibiting dysplasia (containing abnormal cells or showing abnormal development).
Identifying cancerous moles
Melanoma is the most serious type of skin cancer. It develops from melanin-containing cells, called melanocytes. People with fair skin, red or blond hair or who spend a lot of time in strong sunlight are at higher risk of developing melanoma. It is important to avoid prolonged sun or other UV radiation exposure to reduce the risk of developing cancerous moles.
Potential indicators that a mole is cancerous include:
Moles with 3 or more different shades of brown or black are particularly likely to be melanoma. The following alphabetic mnemonic (ABCDE) is a useful way to remember the important signs of moles that could be cancerous. If a mole suddenly begins to display any of the signs listed below, it is important to have it examined by a dermatologist:
- Asymmetry: changing shape, in particular if the mole develops an irregular edge.
- Border: the border or edges of the mole become ragged, blurred, or irregular.
- Color: getting darker, becoming patchy or multi shaded; the color of the mole may have shades of tan, brown, black, blue, white, or red.
- Diameter: the mole may get bigger; enlargement of a mole is especially concerning if the diameter becomes larger than the eraser of a pencil.
- Elevation/Evolution: A mole appears elevated, or raised from the skin, and may look inflamed, bleed or become crusty.
Visit a dermatologist (skin doctor) immediately if there are any noticeable changes in a mole's color, height, size, or shape. It is also vital to have one’s moles checked if they bleed, ooze, itch, appear scaly, or become tender or painful.
If a dermatologist believes a mole needs to be evaluated further to find out whether it is cancerous, they will conduct a biopsy. This involves shaving or cutting out the mole so that it can be examined under the microscope. If the mole is found to be cancerous, the dermatologist will remove the entire mole or scar from the biopsy site by cutting out the entire area and a rim of normal skin around it, and suture the wound (stitch the wound to close it).
Removing benign moles
Even though benign moles are harmless, many people opt to have them removed. Most people who seek to have a benign mole removed do so for cosmetic reasons (when one is embarrassed about how a particular mole or moles look) or practical reasons such as if they snag on clothing or impede shaving.
Scarring is a possible consequence of removing a benign mole. With scarring in mind, the location of the mole and the likely aesthetic development of the scar should be considered before a benign mole is removed, especially in cases where the procedure has been sought for cosmetic reasons.
Methods of mole removal include:
Common methods of removing benign moles include burning them off with an electric current which passes through a wire that becomes hot and is used to burn off the upper layers of the skin. The heat helps prevent bleeding. More than one treatment may be needed to remove a mole.
Alternatively, moles can be cut or "shaved" off the skin. Some moles may have subcutaneous cells (which reside underneath the skin), so the doctor might need to make a deeper cut to remove the entire mole to prevent it from growing back. The cut may require stitches.
Moles can also be frozen off with liquid nitrogen. The dermatologist will swab or spray a small amount of super-cold liquid nitrogen on the mole or skin tag. After a benign mole has been frozen off, there might be a blister where the mole or skin tag was, but this usually heals on its own
By taking appropriate measures to avoid sun damage, a person can:
- Prevent new benign moles from developing
- Prevent existing benign moles from becoming cancerous
When spending time in direct sunlight, always:
- Wear sunscreen with a high sun protection factor (SPF), such as SPF 50
- Use sun-protective clothing, such as wide-brimmed hats, sleeves and long pants
- Seek shade regularly
- Stay out of the sunlight between peak hours, (around 10am to 4pm)
Benign mole FAQ’s
Q: Can a benign mole grow back after removal?
A: If a mole has been removed by cutting it off so that it is level with the skin, some cells may remain below the skin. These can act as a “seed” and cause the mole to regrow. It is not possible to predict whether a mole will grow back. The chances of a mole growing back are greatly reduced if care is taken to remove the subcutaneous cells during the initial procedure.
Q: Can a benign mole become cancerous?
A: Melanoma can develop anywhere in the surface of the skin, including sites occupied by benign moles or within the tissue of the mole itself. For this reason, it is important to consult a physician if the mole undergoes any changes, as these may be signs that it has become cancerous.
**Q: Can a benign mole change color? **
A: Yes, a benign mole can change color over time. Most commonly, moles change color by getting darker after exposure to sunlight. Moles which change color are not necessarily a cause for concern, but could indicate the presence of melanoma, so it is advisable to have them checked by a doctor.