10 Warning Signs and Symptoms of Skin Cancer You Should Never Ignore

Skin cancer is the most common type of cancer globally, affecting millions of people each year. It occurs when abnormal cells in the skin grow uncontrollably, typically due to damage from ultraviolet (UV) radiation from the sun or tanning beds. Early detection is crucial for successful treatment outcomes, making it essential to recognize the warning signs and symptoms of skin cancer.

While skin cancer can develop anywhere on the body, it most commonly appears on areas exposed to the sun, such as the face, neck, arms, and hands. There are three main types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and melanoma. Melanoma is the most serious type, though less common, as it can spread to other parts of the body if not detected early.

Understanding what to look for can save your life. Here are the ten most important symptoms and warning signs of skin cancer that everyone should know.

1. Changes in Existing Moles

One of the most significant warning signs of skin cancer, particularly melanoma, is when an existing mole begins to change in appearance. This is often the first symptom that alerts people to a potential problem.

Pay close attention to moles that:

• Grow larger in size
• Change color or become darker
• Develop irregular borders or edges
• Become raised when they were previously flat
• Start to itch, hurt, or feel tender
• Bleed or ooze fluid
• Develop a crusty surface

Most normal moles remain stable throughout your life. Any mole that begins to evolve or transform should be examined by a dermatologist promptly. Melanoma often develops from existing moles, so monitoring changes is a critical part of early detection.

2. Asymmetry in Skin Lesions

Asymmetry is a key characteristic to watch for when examining your skin. This refers to when one half of a mole, spot, or lesion doesn’t match the other half in shape, color, or thickness.

Normal, benign moles are typically symmetrical – if you were to draw a line through the middle, both halves would look roughly the same. In contrast, cancerous lesions often display irregular growth patterns, making them asymmetrical. One side might be larger, have a different texture, or contain different colors than the other side.

The “A” in the ABCDE rule for melanoma detection stands for Asymmetry, highlighting its importance as an early warning sign. When checking your skin, imagine folding each spot in half. If the two halves don’t match, it warrants further medical evaluation.

3. Irregular or Poorly Defined Borders

The border or edge of a skin lesion provides important clues about whether it might be cancerous. Skin cancer spots often have borders that are irregular, ragged, notched, or blurred, rather than smooth and well-defined.

Characteristics of concerning borders include:

• Edges that fade into the surrounding skin
• Uneven or scalloped borders
• Borders that are difficult to distinguish clearly
• Jagged or notched edges
• Borders that seem to spread outward irregularly

Benign moles typically have crisp, clear borders that are easy to see where the mole ends and normal skin begins. When borders become unclear or irregular, it may indicate that cells are growing abnormally and spreading in an uncontrolled manner, which is characteristic of cancer.

4. Color Variations and Multiple Colors

Normal moles are usually a single shade of brown or tan. When a spot on your skin displays multiple colors or unusual color variations, it’s a significant warning sign that should not be ignored.

Suspicious color patterns include:

• Multiple shades of brown, tan, or black within the same lesion
• Areas of red, white, or blue coloring
• Patches that appear pink, gray, or even purple
• Uneven color distribution throughout the spot
• Very dark black coloring
• Loss of color in certain areas

Melanoma, in particular, often displays a variety of colors due to the different depths at which cancer cells grow in the skin and the varying amounts of pigment they produce. Any spot with two or more distinct colors should be evaluated by a healthcare professional.

5. Diameter Larger Than 6mm

Size matters when it comes to identifying potential skin cancer. Lesions with a diameter larger than 6 millimeters (about the size of a pencil eraser) are more likely to be melanoma, though it’s important to note that melanomas can also be smaller.

When assessing size, consider:

• Comparing the spot to a pencil eraser as a reference point
• Monitoring any growth over time, even if starting small
• Being aware that larger spots have higher risk
• Not dismissing smaller spots that have other warning signs

While many melanomas are larger than 6mm when detected, some are found at earlier stages when they’re smaller. The “D” for Diameter in the ABCDE rule serves as a general guideline, but any suspicious spot should be checked regardless of size, especially if it’s growing or has other concerning features.

6. Evolution or Changes Over Time

Perhaps the most critical symptom to monitor is evolution – any change in a skin spot over time. The “E” in the ABCDE rule stands for Evolving, and this characteristic is often the most telling sign of skin cancer.

Watch for lesions that:

• Change in size, either growing larger or smaller
• Alter in shape or become more irregular
• Change in color, becoming darker, lighter, or developing new colors
• Begin to cause symptoms like itching, tenderness, or pain
• Start to bleed, crust, or ooze
• Develop a different texture or surface appearance
• Become more raised or elevated

Cancerous lesions tend to change and evolve, while benign moles typically remain stable. Taking photos of suspicious spots and comparing them over weeks or months can help track any evolution. Any spot on your skin that looks different from your other moles or is changing should be examined promptly.

7. Sores That Don’t Heal

A persistent sore that doesn’t heal is a hallmark symptom of both basal cell carcinoma and squamous cell carcinoma, the two most common types of skin cancer. These lesions may appear as open sores, wounds, or ulcers that seem to heal and then reopen.

Characteristics of non-healing sores include:

• Sores that persist for more than four weeks
• Wounds that heal but repeatedly break open again
• Sores that bleed easily with minor trauma
• Crusty or scaly patches that won’t resolve
• Persistent ulcers that ooze or form scabs
• Raised edges around a central depression or crater

Normal cuts, scrapes, or minor skin injuries should heal within a couple of weeks. When the skin’s normal healing process is disrupted by cancer cells, wounds fail to close properly. This is particularly common on sun-exposed areas like the face, ears, neck, and hands.

8. Pearly or Waxy Bumps

Basal cell carcinoma, the most common type of skin cancer, often appears as a pearly, waxy, or translucent bump on the skin. This distinctive appearance is one of the key symptoms that helps distinguish it from other skin conditions.

These bumps typically:

• Have a shiny, pearl-like or translucent quality
• May be skin-colored, pink, red, or slightly brown
• Often appear on sun-exposed areas, especially the face and neck
• Can have visible blood vessels on the surface
• May have a central depression or indentation
• Sometimes develop a crusty center that bleeds
• Grow slowly over months or years

These bumps might be mistaken for normal skin blemishes or pimples initially, but unlike acne, they don’t resolve on their own. The pearly appearance is due to how light reflects off the abnormal cell structure. If you notice a persistent, shiny bump on your skin, especially on your face, it should be evaluated by a dermatologist.

9. Red, Scaly Patches or Rough Spots

Squamous cell carcinoma and actinic keratosis (a precancerous condition) often present as red, scaly, or rough patches on the skin. These areas feel different to the touch compared to surrounding normal skin.

These patches may:

• Feel rough, dry, or scaly like sandpaper
• Appear red, pink, or skin-colored
• Have a crusty or wart-like surface
• Be raised or slightly elevated
• Feel tender, itchy, or irritated
• Bleed easily when scratched or rubbed
• Develop on sun-exposed areas like the face, scalp, ears, neck, arms, and hands
• Gradually grow larger over time

These rough patches are caused by the accumulation of abnormal skin cells and keratin buildup. They’re particularly common in people with fair skin who have had extensive sun exposure. While actinic keratoses are considered precancerous, some can progress to squamous cell carcinoma if left untreated, making early detection and monitoring important.

10. Dark Streaks Under Nails

A less common but important symptom of melanoma is the appearance of dark streaks or bands under the fingernails or toenails. This subtype, called acral lentiginous melanoma or subungual melanoma, can be easily overlooked or mistaken for a bruise.

Warning signs include:

• A dark brown or black vertical streak running from the cuticle to the tip of the nail
• A band that widens over time rather than remaining stable
• Darkening of the skin around the nail (Hutchinson’s sign)
• Pigmentation that extends to the cuticle or nail fold
• Changes in a single nail rather than multiple nails
• A streak that appears without a history of nail injury
• Irregularity in color or width of the band

Unlike a bruise, which grows out with the nail and fades over time, melanoma under the nail remains stationary at the base or extends along the entire nail length. This type of melanoma is more common in people with darker skin tones and is sometimes diagnosed later because it’s an unexpected location. Any persistent dark streak under a nail should be examined by a dermatologist, especially if it’s changing or appears without explanation.

Main Causes of Skin Cancer

Understanding what causes skin cancer can help with prevention and awareness. The primary causes include:

Ultraviolet (UV) Radiation Exposure

The leading cause of skin cancer is exposure to UV radiation from the sun or artificial sources like tanning beds. UV rays damage the DNA in skin cells, leading to mutations that can cause cancer. Both UVA and UVB rays contribute to skin cancer risk, with cumulative exposure over a lifetime increasing the likelihood of developing the disease.

Fair Skin and Lack of Melanin

People with fair skin, light hair, blue or green eyes, and those who freckle or burn easily have less melanin, the pigment that provides some protection against UV radiation. This makes them more susceptible to skin cancer, though people of all skin tones can develop the disease.

History of Sunburns

Severe sunburns, especially during childhood and adolescence, significantly increase the risk of developing melanoma later in life. Even one blistering sunburn can double a person’s lifetime risk of melanoma.

Family History and Genetics

Having a family history of skin cancer, particularly melanoma, increases your risk. Certain genetic conditions and inherited traits can make individuals more susceptible to developing skin cancer.

Weakened Immune System

People with weakened immune systems, whether from medical conditions, organ transplantation, or certain medications, have a higher risk of developing skin cancer, particularly squamous cell carcinoma.

Exposure to Certain Chemicals

Occupational exposure to certain chemicals like arsenic, coal tar, and certain petroleum products can increase skin cancer risk.

Age and Cumulative Sun Exposure

Skin cancer risk increases with age as the cumulative effects of sun exposure build up over time. Most skin cancers are diagnosed in people over 50, though younger people can also develop it, particularly if they have other risk factors.

Many Moles or Atypical Moles

Having more than 50 moles or having atypical (dysplastic) moles increases melanoma risk, as these can potentially transform into cancer.

Prevention of Skin Cancer

While not all skin cancers can be prevented, there are effective strategies to significantly reduce your risk:

Sun Protection Practices

• Apply Sunscreen Daily: Use broad-spectrum sunscreen with SPF 30 or higher on all exposed skin, even on cloudy days. Reapply every two hours and after swimming or sweating.
• Seek Shade: Limit sun exposure during peak hours (10 AM to 4 PM) when UV rays are strongest.
• Wear Protective Clothing: Cover skin with long sleeves, long pants, wide-brimmed hats, and UV-blocking sunglasses.
• Avoid Tanning Beds: Completely avoid artificial UV tanning devices, which significantly increase skin cancer risk.

Regular Skin Self-Examinations

Perform monthly skin self-exams to check for new spots or changes in existing moles. Use a full-length mirror and handheld mirror to examine all areas of your body, including hard-to-see places like your back, scalp, and between toes. Familiarize yourself with your normal skin pattern so you can quickly identify changes.

Professional Skin Screenings

Schedule regular skin examinations with a dermatologist, especially if you have risk factors like fair skin, family history, or many moles. Annual professional screenings can detect skin cancer in its earliest, most treatable stages.

Protect Children’s Skin

Take extra care to protect children from sun exposure, as childhood sunburns significantly increase lifetime skin cancer risk. Keep infants under 6 months out of direct sunlight, and ensure children wear sunscreen and protective clothing when outdoors.

Know Your Risk Factors

Be aware of your personal risk factors including skin type, family history, and previous sun exposure. If you’re at higher risk, be extra vigilant about protection and screening.

Vitamin D Considerations

While sun exposure helps produce vitamin D, you can obtain adequate vitamin D through diet and supplements without the cancer risk associated with excessive UV exposure. Consult your healthcare provider about appropriate vitamin D intake.

Frequently Asked Questions

What does early stage skin cancer look like?

Early stage skin cancer can appear as a new spot, a changing mole, a small pearly bump, a flat scaly patch, or a sore that doesn’t heal. It often develops on sun-exposed areas and may be pink, red, brown, black, or skin-colored. The key is identifying changes or new growths on your skin.

How quickly does skin cancer spread?

The spread rate varies by type. Basal cell carcinoma grows slowly and rarely spreads. Squamous cell carcinoma grows faster and can spread if untreated. Melanoma can spread quickly, sometimes within weeks to months, which is why early detection is critical.

Can skin cancer appear suddenly?

Yes, some skin cancers, particularly melanoma, can appear as new spots relatively suddenly. However, most skin cancers develop gradually over months or years. Any new growth that appears and persists should be evaluated by a doctor.

Is skin cancer painful?

Skin cancer is often painless in its early stages, though some people experience itching, tenderness, or discomfort. Pain is not a reliable indicator – many dangerous skin cancers cause no pain at all until advanced stages.

Who is most at risk for skin cancer?

People with fair skin, light hair, blue or green eyes, those with a history of sunburns, extensive sun exposure, family history of skin cancer, many moles, weakened immune systems, and older adults are at higher risk. However, anyone can develop skin cancer regardless of skin tone.

Where does skin cancer most commonly appear?

Skin cancer most often develops on sun-exposed areas including the face, neck, ears, scalp (especially in bald men), shoulders, back, arms, and hands. However, it can occur anywhere on the body, including areas rarely exposed to sun like the palms, soles, and under nails.

Can skin cancer be cured?

Yes, most skin cancers are highly curable when detected and treated early. Basal cell and squamous cell carcinomas have cure rates above 95% with early treatment. Melanoma is also highly curable when caught early but becomes more difficult to treat once it spreads.

Should I see a doctor for every suspicious spot?

Yes, it’s better to be cautious. If you notice any new growth, changing mole, sore that doesn’t heal, or spot with concerning features (asymmetry, irregular borders, multiple colors, large diameter, or evolution), schedule an appointment with a dermatologist. Early detection saves lives.

How is skin cancer diagnosed?

Skin cancer is diagnosed through visual examination and biopsy. A dermatologist examines suspicious areas and may perform a skin biopsy, removing a small sample of tissue for laboratory analysis. The biopsy confirms whether cancer is present and identifies the type.

Can you have skin cancer and not know it?

Yes, many people have skin cancer without realizing it, especially in early stages when lesions may be small or resemble benign spots. This is why regular self-examinations and professional skin screenings are important for early detection.

References:

• American Cancer Society – Skin Cancer
• The Skin Cancer Foundation – Skin Cancer Information
• American Academy of Dermatology – Skin Cancer
• Mayo Clinic – Skin Cancer
• National Cancer Institute – Skin Cancer
• NHS – Skin Cancer