We understand the concerns surrounding changes to skin lesions, particularly moles, and the possibility that one might signal a form of skin cancer such as Melanoma. In this article, we detail the telling signs that a mole or pigmented skin spot should be evaluated by a medical specialist, and provide clear guidance on next steps. Our aim is to provide you a comprehensive, detailed reference—so you are empowered and can act early if needed.
Understanding What Is Normal vs What Is Suspicious
Before diving into specific warning signs, it’s helpful to know the baseline appearance of common (benign) moles and how they differ from those that may require concern.
Typical Benign Mole Features
- Usually appear in childhood or early adulthood, stabilising over time.
- Colour: uniform – tan, brown or black in lighter-skin individuals; often darker in other skin types.
- Shape: round or oval, smooth border, symmetrical halves (if you draw a line down the middle).
- Size: generally less than about 6 mm across (≈ pencil-eraser size).
- Stability: very little change over months or years.
When to Be Alert A mole that diverges from these benign characteristics may warrant further review. Increasingly, dermatologists emphasise that change in a mole is one of the most important red flags.
Six Key Signs That a Mole Needs Urgent Review
Below, we outline six major warning signs that indicate the need for prompt consultation with a skin-cancer specialist. Each sign is supported by the latest clinical guidance.
1. Asymmetry – One-Half Doesn’t Match the Other
If you draw an imaginary line through the mole and one half doesn’t mirror the other in size, shape or colour, this asymmetry is a warning flag. For melanomas, asymmetry is a commonly cited feature.
2. Border Irregularity – Edges are Ragged, Notched or Blurred
Benign moles tend to have smooth, even borders. But when the border becomes ragged, scalloped or transitions into the surrounding skin in an irregular fashion, it is suspicious.
3. Colour Variation – Multiple Colours or Unusual Shades
Normal moles are typically one uniform colour. A mole showing multiple colours (for example, different shades of brown, black, red, white or blue), or one that’s darker than others around it, signals caution.
4. Diameter Increase – Larger Than 6 mm or Growing
Moles that exceed about 6 mm (¼ inch) in diameter, or continue to grow, are more likely to be malignant. However, smaller lesions can also be dangerous, so growth or change is more important than size alone.
5. Evolving – Change in Size, Shape, Surface, or Symptoms
Perhaps the most important sign: a mole that changes over time. This includes changes in height (becoming raised), bleeding, crusting, becoming itchy or tender, or alterations in its surface texture.
6. The “Ugly Duckling” Sign
One Mole Stands Out Even if a mole does not tick all the ABCDE boxes (asymmetry, border, colour, diameter, evolving), it may still be suspicious if it looks distinctly different compared with your other moles. This is known as the “ugly duckling” sign.
Additional Suspicious Features Beyond the Core Six
While the six signs above cover most high-risk features, other less-obvious changes should also prompt evaluation:
- A sore that doesn’t heal, or a scab-like lesion that persists.
- Pigment that spreads beyond the border of the mole into surrounding skin.
- A new mole in adulthood (especially after age 40) that appears suddenly or grows fast.
- A dark streak under a fingernail or toenail, or a lesion on the palm or sole — especially in skin of colour.
- Itching, tenderness or pain associated with a mole. While many benign lesions can itch, persistent or new symptoms are worth assessing.
Risk Factors That Increase the Likelihood of Skin Cancer
Understanding predisposing factors can help contextualise when heightened vigilance is needed. The following increase the probability of a mole becoming cancerous:
- History of sunburns, especially blistering burns, or frequent exposure to ultraviolet (UV) radiation (including tanning beds).
- A personal or family history of skin cancer.
- Having many moles (sometimes >50) or having atypical/dysplastic moles.
- Fair skin, light hair, skin that burns easily — though cancers also occur in darker skin tones and less sun-exposed areas.
- Weakened immune system (for example due to medications or chronic illness).
What You Should Do if You Notice a Suspicious Mole
Immediate Next Steps
- Schedule a skin check: Contact a qualified skin-cancer specialist as soon as possible if you observe one or more of the warning signs above.
- Document the lesion: Take clear photographs of the mole—capture its size (use a ruler or coin for scale), location, and any change over time. Keep a record of when you first noticed it and what changes occurred.
- Avoid self-diagnosis: Even experienced individuals may misinterpret changes—only a trained clinician can confidently determine whether a lesion is benign or malignant.
- Do not postpone: Early detection is strongly associated with better treatment outcomes. For example, melanoma detected early while thin and non-metastatic is far more treatable.
What the Specialist May Do
- Perform a dermatoscopic examination, a specialised skin-microscope inspection.
- If the lesion appears suspicious, perform a biopsy—either shave, punch or excision—to remove the tissue for microscopic pathology.
- Based on findings, advise either active monitoring or full removal and staging if cancer is present.
- Discuss sun-protection strategies and skin-surveillance plans going forward.
Prevention and Skin-Surveillance Strategies
We recommend an ongoing skin health strategy for everyone, but particularly for those with risk factors:
- Adopt daily sun-protection: broad-spectrum SPF 30 or higher, hats, sunglasses, shade during peak UV times.
- Avoid tanning beds and intentional sun-burns—they significantly increase risk.
- Conduct self-skin-checks monthly: examine all areas including scalp, ears, back, buttocks, palms, soles and nails (use mirrors or a partner). A focus on new or changing lesions is key.
Maintain ongoing follow-up with a skin-cancer specialist if you’ve had atypical moles or previous skin cancers.
Summary: When to Get a Mole Checked
In summary, you should promptly consult a specialist if you observe:
- A mole that is asymmetrical, has irregular borders, varied colour, or has grown beyond about 6 mm.
- A mole that’s evolving—changing in size, shape, colour, texture—or one that starts to itch, bleed, crust or become tender.
- A new mole in adulthood, or one that stands out as the “ugly duckling” compared to your other moles.
- Any ulcerated, persistent sore on the skin, or pigment spread from a mole into adjacent skin, or a suspicious mark under a nail or in a rarely-observed location.
- Especially if you have significant sun-exposure history, prior skin-cancer history, many moles or immune-system suppression.
By acting early and seeking specialist evaluation when needed, you significantly enhance the chances of early detection and successful treatment. Stay vigilant, protect your skin, and make sure any change is checked—because when it comes to skin health, timing truly matters.