How can I tell if a mole is Cancerous or Non-Cancerous by looking at it?

Moles are a type of skin growth that many people have. They look like small, dark brown spots and happen when some cells in our skin (called melanocytes) make too much pigment. People usually get 10 to 40 moles during their childhood and teenage years, and they can change or disappear over time [1].

In most cases, moles are not dangerous and pose no harm to our health. However, rarely, they can develop into cancer. That’s why it’s crucial to keep an eye on any changes that could indicate cancer growth. By staying vigilant, you can help detect skin cancer early on, particularly malignant melanoma.

In this blog article, we will discuss how you can differentiate between benign and cancerous moles and other skin conditions by looking at them. So, if you are worried about a brownish speckle on your body, this information will significantly help you. Read ahead.

How to Distinguish Various Types of Moles by Their Look?

For simplicity, dermatologists (skin doctors) classify moles into four major categories.

1. Congenital Moles
2. Acquired Moles
3. Atypical Moles
4. Melanoma

1. Congenital Moles (non-cancerous)

According to the American Osteopathic College of Dermatology (AOCD), congenital moles are present from birth, occurring in around 1 out of every 100 newborns [2]. These moles can be flat and come in different textures and colors, but most do not turn cancerous.

Even though all congenital moles are non-cancerous and don’t have any clinical significance, they can be further classified into four types based on appearance.

a. Intradermal Nevus

An intradermal nevus is a mole with cells located in the deeper layer of the skin. It can appear as a raised bump with a smooth or warty surface.

Intradermal nevi have the following features [3]:

• They are the same color as the surrounding skin.
• They are small, typically between 5 mm and 1 cm in size.
• They are raised from the skin’s surface and have a rounded, dome-shaped, pedunculated, or warty appearance.
• They may be associated with hair growth, especially in older patients.

b. Junctional Nevus

Junctional moles are harmless growths in the skin cells and are present where the epidermis and dermis meet (epidermal-dermal junction). They are small, grow symmetrically, and have evenly placed cells that look normal under a microscope [4]. In addition, they are easy to distinguish from other types of growths because of their distinct borders.

c. Compound Nevus

Compound moles have nests of nevus cells in the epidermal-dermal junction (corresponding to junctional moles) and dermis (corresponding to intradermal moles). The features of their identification include [5], 

• Compound nevi have a raised central area that is darker in color, surrounded by a flatter area with lighter tan-brown pigmentation. 
• The pigmentation may not be even but is usually distributed symmetrically. 
• These nevi are usually round or oval-shaped and have a diameter of 2-7 mm. 
• They may vary in pigmentation and sometimes be the same color as the surrounding skin.

d. Combined Nevus

Combined nevi are uncommon moles identified by the presence of pigmentation from two or more types of moles in one area. Unfortunately, you can’t identify it just by looking at it, as the correct diagnosis of combined nevi requires microscopic investigations. Still, after examination by an expert, they tend to be mistakenly diagnosed as melanoma based on clinical and microscopic characteristics, which could lead to incorrect treatment, patient distress, and legal issues [6].

Congenital moles can be found anywhere on the body, but they are most common on the back, buttocks, and shoulders. They are more common in people with fair skin and a family history of skin cancer.

If you have a congenital mole, it is important to see your doctor for regular skin checks. Your doctor may recommend removing the mole, or they may simply monitor it to see if it changes.

2. Acquired Moles (non-cancerous)

Moles that appear later in life are called acquired moles. They are primarily brown and are associated with UV rays or sun exposure. These moles usually stay the same shape as you age and are not likely to turn into melanoma, although they may get darker with age.

The two primary distinguishing features of acquired moles are that they are non-cancerous and develop later in life, setting them apart. However, experts categorize acquired moles into two groups classically based on their color.

a. Blue Nevus

A “blue nevus” is a skin lesion that appears as a blue nodule on the head, limbs, or buttocks. These lesions can be acquired, meaning they appear later in life as a single bump, or congenital, meaning they are present from birth and may appear in multiple locations [7].

b. Dark Nevus

A dark nevus is a skin lesion similar to a blue nevus but appears as a black nodule primarily on the face. Little is known about dark nevus as a separate entity. Therefore, the term dark nevus is arbitrarily used for any dark mole, either congenital or acquired.

3. Atypical Mole (non-cancerous but dangerous)

A dysplastic nevus, sometimes referred to as an atypical mole, is a type of mole that looks different from a typical mole. The easy way to identify a dysplastic nevus is to look for the following features [8],

1. It is typically wider than 5 millimeters.
2. It may have a mix of various colors, ranging from pink to dark brown.
3. It often has a flat appearance and a surface that’s either smooth, slightly scaly, or pebbly.
4. The mole’s border may be irregular and blend into the surrounding skin.

Dysplastic nevi can develop on any body part, but they are more commonly seen in sun-exposed areas like the back. Typically, people who have dysplastic nevi also have an increased number of common moles [8].

While it is uncommon for a dysplastic nevus to turn into melanoma, it is still considered a risk factor for developing this type of skin cancer. Individuals with multiple dysplastic nevi are at a higher risk of developing melanoma, with the risk increasing as the number of dysplastic nevi increases. Studies have shown that someone with more than five dysplastic nevi has about 10 times the risk of developing melanoma than someone without any dysplastic nevi [9].

Dysplastic moles can be found anywhere on the body, but they are most common on the sun-exposed areas of the body, such as the face, neck, and arms. They are more common in people with fair skin and a family history of skin cancer. If you have a dysplastic mole, it is important to see your doctor for regular skin checks. Your doctor may recommend removing the mole, or they may simply monitor it to see if it changes.

4. Melanoma (cancerous)

Melanoma is a skin cancer originating in a particular type of skin cell – melanocytes. What concerns healthcare professionals the most is the potential of melanoma to invade surrounding tissues and metastasize to distant parts of the body, such as the lungs, liver, bones, or brain [10]. Therefore, detecting and removing melanoma as early as possible is critical, increasing the likelihood of successful treatment.

Although the accurate diagnosis of melanoma requires critical investigations, some signs can raise suspicion of cancerous growth. Therefore, healthcare professionals have made an ABCDE rule for the general public representing the features of early melanoma [11, 12]. 

Asymmetry: one half of the mole does not look the same as the other half.

Irregular Border: The mole’s border may be uneven, with rough or blurry edges, with pigments spreading into the surrounding skin. 

Uneven Color: Melanomas may have different colors, such as black, brown, or tan. They may also have white, gray, red, pink, or blue areas. 

Diameter: Melanomas can start small but tend to grow in size, and most are usually larger than 6 millimeters (about a quarter of an inch) in diameter.

Evolving: If a mole changes in size, shape, color, or texture over a few weeks or months, it may be a sign of melanoma.

There are four main types of melanoma:

Superficial spreading melanoma: This is the most common type of melanoma. It starts as a flat, brown, or black spot on the skin. Over time, it may become raised and bumpy. It can occur anywhere on the body, but it is most common on the trunk, back, and legs.

Nodular melanoma: This type of melanoma grows quickly and is often raised and bumpy. It can be any color, but it is most often black or brown. It is most common on the trunk, back, and head.

Lentigo maligna melanoma: This type of melanoma develops slowly over many years. It usually starts as a flat, brown, or black spot on the sun-exposed skin of the face, neck, or hands.

Acral lentiginous melanoma: This type of melanoma occurs on the palms of the hands, soles of the feet, or under the nails. It is more common in people with darker skin.

Melanoma can also be classified by its stage. The stage of melanoma is determined by its size, depth, and whether it has spread to other parts of the body.

Melanoma in situ: This is the earliest stage of melanoma. It is confined to the top layer of the skin.

Melanoma with micro invasion: This stage of melanoma has spread into the deeper layers of the skin, but it has not spread to other parts of the body.

Melanoma with macro invasion: This stage of melanoma has spread into the deeper layers of the skin and has spread to other parts of the body.

Melanoma is a serious type of skin cancer, but it is treatable if it is caught early. If you have any concerns about a mole, see your doctor right away.

How are moles diagnosed?

Doctors conduct a skin examination to diagnose moles by inspecting the skin from head to toe. If a mole is suspected to be cancerous, it is removed and sent to a lab for a biopsy, where it is examined under a microscope.

Other Non-Cancerous or Cancerous Skin Conditions

Other skin conditions resemble melanoma and moles, which can lead to incorrect diagnosis and treatment. Some of these conditions are:

1. Seborrheic keratosis (non-cancerous)

Seborrheic keratosis typically presents as multiple lesions with a textured surface, well-defined edges, and a uniform appearance. In addition, these lesions change very little over time. In contrast, melanoma is usually a single smooth lesion with a ragged or blurry border. In addition, melanoma may be asymmetrical or have multiple colors, and it can grow and change rapidly. These differences in appearance help to distinguish seborrheic keratosis from melanoma [13].

Seborrheic keratosis, also known as basal cell papilloma, senile wart, or brown wart, is a common noncancerous (benign) skin growth. They are usually brown, black, or light tan, and can appear anywhere on the body, but are most common on the face, chest, back, and scalp. Seborrheic keratoses can vary in size from a few millimeters to several centimeters in diameter. They may be flat or slightly raised and may have a rough or smooth surface. Some seborrheic keratoses may itch or bleed, but most are not painful.

The exact cause of seborrheic keratosis is unknown, but they are thought to be caused by a combination of factors, including:

• Age: Seborrheic keratoses are more common in people over the age of 40.

• Genetics: Some people are more likely to develop seborrheic keratoses than others.

• Sun exposure: Sun exposure can increase the risk of developing seborrheic keratoses.

• Certain medical conditions: Seborrheic keratoses are more common in people with certain medical conditions, such as psoriasis, eczema, and HIV/AIDS.

Seborrheic keratoses are usually not harmful, but they may be removed for cosmetic reasons or if they are causing problems, such as itching or bleeding. Treatment options for seborrheic keratoses include:

• Cryotherapy: This involves freezing the growth with liquid nitrogen.

• Curettage: This involves scraping the growth off the skin with a sharp instrument.

• Electrosurgery: This involves using an electric current to destroy the growth.

• Laser therapy: This involves using a laser to remove the growth.

In most cases, seborrheic keratoses are not a cause for concern. However, if you have any concerns about a growth on your skin, it is important to see a doctor to rule out any underlying medical conditions.

2. Dermatofibroma (non-cancerous)

Dermatofibromas are common benign skin growths of fibrous and histiocytic (a type of white blood cell) tissue, while melanomas are potentially dangerous cancerous growths. Distinguishing between the two can sometimes be challenging, making it essential to conduct a histopathological analysis before arriving at a diagnosis [15].

A dermatofibroma is a common, benign (noncancerous) growth of fibrous tissue in the skin. It is also known as fibrous histiocytoma. Dermatofibromas are usually small, round, or oval bumps that are firm to the touch. They are most often found on the lower legs, but they can occur anywhere on the body. Dermatofibromas are usually painless, but they can sometimes be itchy or tender.

The exact cause of dermatofibromas is unknown, but they are thought to be caused by a reaction to trauma to the skin, such as an insect bite or a scratch. Dermatofibromas are more common in women than in men, and they are most common in people between the ages of 20 and 50.

Most dermatofibromas do not require treatment. They will usually go away on their own within a few months to a year. However, if a dermatofibroma is causing problems, such as itching or pain, it can be removed by a doctor. Treatment options for dermatofibromas include:

• Surgical excision: This involves removing the dermatofibroma with a scalpel.

• Cryotherapy: This involves freezing the dermatofibroma with liquid nitrogen.

• Electrosurgery: This involves using an electric current to destroy the dermatofibroma.

• Laser therapy: This involves using a laser to remove the dermatofibroma.

Dermatofibromas are usually harmless growths, but it is important to see a doctor to have them evaluated to rule out any other possible causes of the growth.

3. Basal Cell Carcinoma (cancerous)

Basal cell carcinoma can present as a small, white, or flesh-colored bump. The growth of this bump is typically slow and may cause it to bleed [14].

Basal cell carcinoma (BCC) is the most common type of skin cancer. It starts in the basal cells, which are the cells that make up the bottom layer of the epidermis, the outermost layer of skin. BCCs are slow-growing and rarely spread to other parts of the body, but they can cause disfigurement if they are not treated.

BCCs can appear anywhere on the body, but they are most common in areas that are exposed to the sun, such as the face, neck, and ears. They can also occur in areas that are not exposed to the sun, such as the scalp, genitals, and the mouth.

BCCs can look different from one person to another. Some BCCs are small, smooth, and pink or pearly white. Others are larger and have a scaly or crusty surface. Some BCCs may bleed or ulcerate.

If you have a growth on your skin that is new, changing, or growing, it is important to see a doctor to have it checked out. BCCs are usually easily treated, but early detection is important to prevent them from spreading.

There are several things you can do to reduce your risk of developing BCC, including:

• Avoid excessive sun exposure.

• Wear sunscreen with an SPF of 30 or higher every day, even on cloudy days.

• Wear protective clothing, such as a hat and sunglasses, when you are in the sun.

• Don’t use tanning beds.

• Quit smoking.

• Eat a healthy diet and maintain a healthy weight.

• Get regular checkups from your doctor.

If you have a family history of BCC, you may be at an increased risk for developing the disease. Talk to your doctor about your risk factors and how you can reduce your risk.

4. Squamous Cell Carcinoma (cancerous)

Squamous cell carcinoma can manifest in different ways, such as a firm red bump, a scaly patch, an open sore, or a wart that may crust or bleed easily [14]. Both types of skin cancers, basal & squamous, are more common compared to melanoma.

Squamous cell carcinoma (SCC) is the second most common type of skin cancer, after basal cell carcinoma (BCC). It develops in the squamous cells, which are the flat, thin cells that make up the top layer of the skin. SCCs are more likely to develop in areas of the skin that have been exposed to the sun, such as the face, neck, ears, and hands.

SCCs can start as small, red, scaly patches or bumps. They may grow slowly over time, and they may bleed or crust. If left untreated, SCC can grow larger and spread to other parts of the body.

There are several things you can do to reduce your risk of developing SCC, including:

• Avoid excessive sun exposure.

• Wear sunscreen with an SPF of 30 or higher every day, even on cloudy days.

• Wear protective clothing, such as a hat and sunglasses, when you are in the sun.

• Don’t use tanning beds.

• Quit smoking.

• Eat a healthy diet and maintain a healthy weight.

• Get regular checkups from your doctor.

If you have a family history of SCC, you may be at an increased risk for developing the disease. Talk to your doctor about your risk factors and how you can reduce your risk.

If you notice any changes in your skin, such as a new growth, a sore that doesn’t heal, or a change in the size, shape, or color of a mole, see your doctor right away. Early detection and treatment are important for preventing SCC from spreading.

The following are some of the symptoms of squamous cell carcinoma:

• A new growth on the skin

• A sore that doesn’t heal

• A change in the size, shape, or color of a mole

• Bleeding or crusting on the skin

• Itching or pain in the skin

• A scaly or crusty patch on the skin

If you notice any of these symptoms, see your doctor right away. Squamous cell carcinoma is a serious condition, but it is treatable if it is caught early.

5. Lentigo Maligna (cancerous)

Lentigo maligna is a type of melanoma that typically appears as an irregular brown macule on skin exposed to chronic sunlight, particularly on the head and neck. This type of melanoma is more commonly found in elderly individuals [16].

Lentigo maligna (LM) is a type of skin cancer that develops in the top layer of the skin (epidermis). It is most common on sun-exposed areas of the body, such as the face, neck, and hands. LM is slow-growing and usually does not spread to other parts of the body. However, it can become invasive melanoma, which is a more serious type of skin cancer.

The exact cause of LM is unknown, but it is thought to be caused by a combination of factors, including:

• Sun exposure: LM is most common in people who have had a lot of sun exposure over the years.

• Age: LM is more common in people over the age of 50.

• Fair skin: People with fair skin are more likely to develop LM than people with darker skin.

• Genetics: People with certain genetic mutations are more likely to develop LM.

LM typically starts as a small, flat, brown spot on the skin. The spot may be slightly raised or have a rough texture. It may also be slightly darker than the surrounding skin. Over time, LM may grow larger and become more irregular in shape. It may also change color, becoming darker or lighter.

If you have a spot on your skin that you are concerned about, see your doctor. LM can be easily treated if it is caught early. Treatment options for LM include:

• Excision: This involves surgically removing the LM.

• Mohs micrographic surgery: This is a type of surgery that removes LM layer by layer.

• Cryotherapy: This involves freezing the LM with liquid nitrogen.

• Photodynamic therapy: This involves using a laser to destroy the LM.

With early treatment, LM is usually very curable. However, it is important to see your doctor for regular skin checks so that LM can be caught and treated early.

Therefore, healthcare professionals consider these conditions while examining moles to make an accurate diagnosis and effectively remove the abnormal tissue.

What’s the difference between moles and birthmarks?

Moles are pigmented growths commonly appearing on the skin. As discussed, they can be of various colors, such as brown or black. In addition, they can appear on any part of the body, either as a single growth or in groups. In contrast, a birthmark is a colored mark that typically appears on a baby’s skin soon after birth. So, we can say that all congenital moles are birthmarks, but all birthmarks are not moles.

How do healthcare professionals remove moles?

A dermatologist can easily remove a mole during a regular office visit, but sometimes, you may need a second visit to complete the removal. There are two primary surgical procedures for mole removal [17]: freezing and burning. 

Freezing involves using liquid nitrogen to remove a noncancerous mole, while burning uses an electric current to burn off the top layers of a mole. Shaving is another procedure, using a surgical blade to shave the mole off the skin’s surface. Conversely, excision goes deeper than shaving to remove the entire mole and stitch the skin back together, typically used for cancerous moles. 

After removal, a dermatologist can evaluate the mole for skin cancer if necessary. After evaluation, you are allowed to go home in no time. 

Note: Don’t try to remove moles at home as it increases your chances of getting infection and injuries. 

When should I see a doctor?

Dermatologists suggest getting a yearly skin examination to look for any changes in existing moles or the presence of any cancerous growth. If you notice any unusual changes in your skin in between appointments, it is advisable to schedule an additional appointment.

Some of these changes include:

• New moles that grow quickly
• Moles that suddenly change shape or size
• Itchy moles
• Moles that bleed or appear infected without injury

Here are some tips for checking your skin for common moles:

* Stand in front of a full-length mirror and look at your entire body.

* Use a hand mirror to check the back of your body.

* Have someone else check your back, scalp, and other hard-to-see areas.

* Pay attention to the size, shape, color, and texture of your moles.

* If you notice any changes in a mole, see your doctor right away.

If you have over 50 acquired moles, you may have a greater chance of developing cancerous skin lesions, as per the AAD. The good news is that if melanoma is detected early, it can significantly increase the chances of survival. According to a reliable source, the 10-year survival rate for early detected melanoma is 93% [18].

References

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2. American Osteopathic College of Dermatology. Moles – American Osteopathic College of Dermatology (AOCD) [Internet]. www.aocd.org. [cited 2023 Apr 20]. Available from: https://www.aocd.org/page/Moles

3. Intradermal and Compound Naevi. Naevus Intradermal Info [Internet]. patient.info. [cited 2023 Apr 21]. Available from: https://patient.info/doctor/intradermal-and-compound-naevi

4. Busam KJ, Scolyer RA, Pedram Gerami. Pathology of melanocytic tumors. Amsterdam: Elsevier; 2019.

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8. Friedman RJ, Farber MJ, Warycha MA, Papathasis N, Miller MK, Heilman ER. The “dysplastic” nevus. Clinics in Dermatology. 2009 Jan;27(1):103–15.

9. Goldstein AM, Tucker MA. Dysplastic Nevi and Melanoma. Cancer Epidemiology Biomarkers & Prevention. 2013 Apr 1;22(4):528–32.

10. Schadendorf D, van Akkooi ACJ, Berking C, Griewank KG, Gutzmer R, Hauschild A, et al. Melanoma. The Lancet [Internet]. 2018 Sep;392(10151):971–84. Available from: https://www.sciencedirect.com/science/article/pii/S0140673618315599?via%3Dihub

11. Goodson AG, Grossman D. Strategies for early melanoma detection: approaches to the patient with nevi. Journal of the American Academy of Dermatology [Internet]. 2009 May 1 [cited 2021 Nov 22];60(5):719–38. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2690513/

12. Rigel DS, Russak J, Friedman R. The Evolution of Melanoma Diagnosis: 25 Years Beyond the ABCDs. CA: A Cancer Journal for Clinicians. 2010 Jul 29;60(5):301–16.

13. Seborrheic Keratosis: What Is It, Causes, Risks & Treatment [Internet]. Cleveland Clinic. [cited 2023 Apr 25]. Available from: https://my.clevelandclinic.org/health/diseases/21721-seborrheic-keratosis

14. What’s the Difference Between Melanoma and Skin Cancer? [Internet]. Dana-Farber Cancer Institute. 2019 [cited 2023 Apr 25]. Available from: https://blog.dana-farber.org/insight/2019/12/difference-between-melanoma-and-skin-cancer/

15. Kovach BT, Boyd AS. Melanoma associated with a dermatofibroma. Journal of Cutaneous Pathology. 2007 May 1;34(5):420–2.

16. Xiong M, Charifa A, Chen CSJ. Lentigo Maligna Melanoma. [Updated 2022 Oct 31]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482163/

17. Watson S. How to Remove Moles [Internet]. Healthline. Healthline Media; 2017 [cited 2019 Dec 13]. Available from: https://www.healthline.com/health/how-to-remove-moles.

18. Webster DE, Suver C, Doerr M, Mounts E, Domenico L, Petrie T, et al. The Mole Mapper Study, mobile phone skin imaging, and melanoma risk data were collected using ResearchKit. Scientific Data [Internet]. 2017 Feb 14;4(1):170005. Available from: https://www.nature.com/articles/sdata20175