Most freckles are harmless, but certain visual clues can signal that a spot on your skin is melanoma. The key is knowing what to look for: irregular shape, uneven color, changing size, and spots that look different from everything else on your body. Roughly 70% to 80% of melanomas appear as entirely new spots rather than changes in existing freckles or moles, so watching for new arrivals matters just as much as monitoring the ones you already have.
The ABCDE Rule for Spotting Melanoma
The most widely used framework for evaluating a suspicious spot is the ABCDE rule, developed by the National Cancer Institute. Each letter represents a visual warning sign:
- Asymmetry: One half of the spot doesn’t match the other. Normal freckles and moles tend to be roughly symmetrical.
- Border: The edges are ragged, notched, or blurred rather than smooth and well-defined. Pigment may appear to spread into the surrounding skin.
- Color: Multiple shades are visible within the same spot. A mix of brown, tan, black, or the presence of white, gray, red, pink, or blue areas is concerning. Ordinary freckles are usually a single, uniform shade of brown.
- Diameter: The spot is larger than about 6 millimeters, roughly the size of a pencil eraser. Melanomas can be smaller than this, but most exceed it.
- Evolving: The spot has changed in size, shape, or color over the past few weeks or months. Any new symptom like itching, bleeding, or crusting also counts.
A freckle that checks none of these boxes is almost certainly benign. A spot that meets even one of them, especially “E” for evolving, deserves a closer look from a dermatologist.
The Ugly Duckling Sign
If you have many freckles or moles, the ABCDE rule can be hard to apply to every single one. A faster screening method is the “ugly duckling” sign: look for the one spot that doesn’t match the rest. Most of your moles probably share a similar size, shape, and color. If one stands out because it’s darker, larger, more raised, or has scabbed over, that outlier is worth getting checked. This approach catches melanomas that might individually seem borderline on the ABCDE scale but clearly look “off” compared to their neighbors.
Melanomas That Don’t Look Like Melanomas
Not every melanoma is a dark, irregular blotch. Some types are easy to miss because they break the usual rules.
Amelanotic Melanoma
About 2% to 8% of melanomas contain little or no pigment. Instead of brown or black, they appear pink, red, or skin-colored. They can look like a pimple that won’t heal, a small raised bump with a smooth or shiny surface, or a patch of irritated skin. Because they lack the dark coloring most people associate with melanoma, they’re frequently mistaken for other conditions. If you have a pink or reddish bump that persists for several weeks without an obvious cause, it’s worth having it examined.
Nodular Melanoma
This type grows vertically into the skin rather than spreading outward, which means it can be small and symmetrical, sometimes under 6 millimeters. It often appears as a raised, firm bump that grows noticeably over weeks. The key warning signs are captured by the EFG criteria: elevated above the skin surface, firm to the touch, and growing progressively. Nodular melanomas are frequently diagnosed at a later stage because they don’t fit the typical ABCDE profile, so a new bump that keeps getting bigger is a red flag even if it looks round and even.
Melanoma Under the Nail
Subungual melanoma shows up as a dark streak or band running lengthwise under a fingernail or toenail. One important clue is the Hutchinson sign, where the dark pigment spreads beyond the nail onto the surrounding skin of the cuticle or fingertip. This type of melanoma is more common on the thumb and big toe and is often mistaken for a bruise or fungal infection. A bruise under the nail grows out with the nail over time, while a melanoma streak stays in place or widens.
Normal Freckles vs. Suspicious Spots
Ordinary freckles (ephelides) are flat, small, uniformly tan or light brown, and tend to fade in winter. Sun spots, also called solar lentigines or age spots, are slightly larger flat patches that don’t fade seasonally but remain a consistent, even color. Both types have smooth, well-defined borders.
What separates a harmless spot from a concerning one comes down to three core features: uniformity, stability, and borders. A benign freckle or sun spot is one color, stays the same over time, and has clean edges. A melanoma typically breaks at least one of those rules. The trickiest overlap is between a large sun spot and a very early melanoma called lentigo maligna, which can develop within sun-damaged skin. Dermatologists use a magnifying tool called a dermatoscope to examine the internal structure of the spot, looking for patterns that indicate whether pigment cells are behaving normally or growing abnormally.
How to Do a Self-Exam
A thorough self-check takes about 10 minutes once a month. You need a full-length mirror, a hand mirror, and good lighting. Work through your body systematically: face, scalp (use a comb to part your hair), ears, neck, chest, abdomen, arms (lift them to check the sides of your torso), hands including between the fingers, legs, feet including the soles and between the toes, and your back using the hand mirror. Ask a partner to help with areas you can’t see well.
You’re not trying to diagnose anything during a self-exam. You’re building a mental map of what’s normal for your skin so that changes stand out. Some people photograph their moles every few months to make comparison easier. The goal is to notice when something new appears, when an existing spot changes, or when one spot starts looking different from all the others.
What Happens if a Spot Looks Suspicious
A dermatologist will first examine the spot visually and with a dermatoscope. If it looks concerning, the next step is a biopsy, where a small sample of tissue is removed and examined under a microscope. For a suspected melanoma, the preferred approach is an excisional biopsy, meaning the entire spot is removed along with a small margin of surrounding skin. This gives the pathologist the full thickness of the lesion, which is critical because the depth of the melanoma determines its stage and what treatment follows. For spots that are too large or in difficult locations, a punch biopsy or wedge biopsy can sample a representative section instead.
The biopsy itself is done under local anesthesia in a clinic visit and typically takes less than 30 minutes. Results usually come back within one to two weeks.
Why Early Detection Changes the Outcome
Melanoma caught early is one of the most treatable cancers. When a melanoma is still very thin, 0.5 millimeters or less in depth, the 10-year survival rate is about 99.6%. Even melanomas up to 1 millimeter thick have 10-year survival rates ranging from 82% to 97%. Once a melanoma grows deeper and spreads to lymph nodes or other organs, survival rates drop significantly. The difference between a melanoma caught at 0.5 millimeters and one caught at 3 or 4 millimeters can be enormous, and that gap is often just a matter of months.
This is why monthly self-exams and regular skin checks with a dermatologist matter, especially if you have risk factors like a family history of melanoma, a large number of moles, a history of blistering sunburns, or fair skin that burns easily. People with three or more family members who have had melanoma may also benefit from genetic counseling to assess inherited risk.