Pick a regular day to check your skin from head to toe, and know what you’re looking for: a spot that’s lopsided, ragged at the edges, uneven in color, or changing. Those are the classic warning signs of melanoma, which makes up about 1% of skin cancers but causes the most skin cancer deaths.[1] A photo gallery can show you what these look like, but only a clinician can tell you what a spot is. Here’s the text-only version of what to watch for, how to check, and when to make the call.
The ABCDEs of melanoma
Dermatologists use five letters as a quick screen for moles and other pigmented spots. The American Academy of Dermatology (AAD) says to see a dermatologist right away if a spot shows any of these:[2]
- Asymmetry: one half of the spot doesn’t match the other half.
- Border: the edge is irregular, scalloped or poorly defined.
- Color: the color varies from one area to the next, with shades of tan, brown or black, or patches of white, red or blue.
- Diameter: melanomas are usually bigger than 6 millimeters (about a pencil eraser) when diagnosed, but they can be smaller.
- Evolving: the spot looks different from the rest, or it’s changing in size, shape or color.
The E carries a lot of weight. When researchers reviewed the evidence in 2004, they found no support for lowering the 6 mm cutoff, but they did back adding “evolving” to the original ABCD list. Their advice: watch for changes in size, shape, symptoms such as itching or tenderness, surface changes (especially bleeding), and shades of color.[3] So a spot that’s changing is worth showing someone even if it passes the A-to-D tests.
The ugly duckling check
Here’s a shortcut that doesn’t need a ruler. Most of your moles look like siblings, so look for the one that doesn’t. That’s the ugly duckling sign: a spot that stands out from the others on your body. In one study, nine dermatologists reviewed 2,089 photos of moles from 80 patients, and every melanoma was flagged as an ugly duckling. Comparing a mole against the same person’s other moles also gave fewer false alarms than judging each mole alone (specificity of 0.96 versus 0.88 on clinical photos), and using both approaches together cut the number of moles flagged for biopsy by a factor of 6.9.[4]
It was a photo study with dermatologists doing the judging, so treat it as a reason to scan for the odd one out, not a way to clear a mole yourself.
Other skin cancers don’t follow the ABCDEs
Most skin cancers are basal cell and squamous cell carcinomas, together called keratinocyte carcinoma.[1] They look different from melanoma, and the AAD describes them this way:
- Basal cell carcinoma can look like a firm, round, raised growth (shiny pink or red on lighter skin, brown or black on darker skin), a circle that dips in the center, a scaly patch, a cluster of shiny bumps, a scar-like mark, or a sore that doesn’t heal or heals and returns. It grows slowly and rarely spreads, but it can grow deep and damage the tissue around it. That’s a reason to have a non-healing sore looked at promptly, not to wait.[5]
- Squamous cell carcinoma can look like a rough, scaly patch, a firm dome-shaped growth, a wart-like or horn-like growth, a sore that doesn’t heal, or a change to an existing scar. It may itch, hurt, tingle or bleed, but some people feel nothing at all.[6]
The common thread is a sore or patch that won’t go away. The AAD is also direct about the limits of pictures: you can’t rule skin cancer in or out by looking at photos, which is why a gallery can’t replace an exam.[5]
Spots people forget to check
Nails. Melanoma can develop under and around fingernails and toenails. Look for a brown or black streak in the nail, darker skin next to the nail, a nail lifting off the nail bed, a nail splitting down the middle, or a bump under the nail.[7]
Feet. Check the soles and between your toes, and pay extra attention to any spot where you once injured your foot, even years ago. A melanoma on the foot can also look like a pinkish-red spot, a rapidly growing mass, or a sore that won’t heal. For people of African or Asian ethnicity, the hands and feet are the most common places for melanoma to appear.[8]
Darker skin tones. Skin cancer is often found later in people with darker skin, but it can be found earlier. The AAD’s three steps: learn the warning signs, check your skin, and see a board-certified dermatologist if anything looks like skin cancer.[9]
How to check your skin at home
The AAD’s skin self-exam takes five steps:[10]
- Stand in front of a full-length mirror and check your front and back, then both sides with your arms raised.
- Bend your elbows and look closely at your forearms, underarms, fingernails and palms.
- Check the backs of your legs and feet, the spaces between your toes, your toenails and the soles of your feet.
- Use a hand mirror to look at the back of your neck and your scalp, parting your hair as you go.
- Use a hand mirror to check your back and buttocks.
A self-check that finds nothing doesn’t rule out skin cancer. Some cancers are hard to see, and some can’t be seen at all.
Two habits make the check more useful. First, take a dated phone photo of any spot you’re unsure about, so next time you’re comparing against a record instead of memory. Second, note where each spot is; the AAD offers a body mole map for exactly that.[10]
When to book an appointment
Make an appointment with a board-certified dermatologist if you notice a new spot, a spot that looks different from the others, or a spot that changes, itches or bleeds.[10] Don’t wait to see whether it settles down.
Stage matters. In US cancer registry data for 2016 to 2022, 77% of melanomas were diagnosed while still confined to the skin, and 5-year relative survival for those was about 100%. For the 5% diagnosed after the cancer had spread to distant sites, 5-year relative survival was 34%.[11] (Relative survival compares people with the cancer to people of the same age and sex without it.)
There’s one wrinkle worth knowing. The US Preventive Services Task Force found the evidence insufficient to judge the benefits and harms of routine visual skin exams by a clinician in people with no symptoms and no history of skin lesions. That statement doesn’t cover people who already have a suspicious spot or a history of skin cancer.[1] So if a spot worries you, don’t wait for a screening slot. If you’ve had skin cancer before, ask your clinician how often you should be examined, and bring your photos.
References
[1] US Preventive Services Task Force; Mangione CM, Barry MJ, Nicholson WK, et al. Screening for Skin Cancer: US Preventive Services Task Force Recommendation Statement. JAMA, 2023;329(15):1290-1295. Population: asymptomatic adolescents and adults without a history of premalignant or malignant skin lesions. DOI: https://doi.org/10.1001/jama.2023.4342. Finding as used: melanomas represent about 1% of skin cancer and cause the most skin cancer deaths; basal and squamous cell carcinomas are the most common types; evidence is insufficient to determine the balance of benefits and harms of visual skin examination by a clinician to screen asymptomatic people (I statement), and the recommendation does not apply to people with a history of premalignant or malignant skin lesions. ↑︎
[2] American Academy of Dermatology. What to look for: ABCDEs of melanoma. https://www.aad.org/public/diseases/skin-cancer/abcdes-melanoma (accessed 2026-10-09). Finding as used: the five ABCDE features (asymmetry, irregular border, varying color, diameter usually greater than 6 mm but can be smaller, evolving), and the advice to consult a dermatologist immediately if a mole or pigmented spot shows them. ↑︎
[3] Abbasi NR, Shaw HM, Rigel DS, Friedman RJ, et al. Early diagnosis of cutaneous melanoma: revisiting the ABCD criteria. JAMA, 2004;292(22):2771-2776. Population: literature review (Cochrane Library and PubMed, 1980-2004). DOI: https://doi.org/10.1001/jama.292.22.2771. Finding as used: data did not support lowering the diameter criterion from greater than 6 mm, but supported expanding ABCD to ABCDE to include evolving lesions; patients and physicians should watch for changes in size, shape, symptoms (itching, tenderness), surface (especially bleeding) and shades of color. ↑︎
[4] Gaudy-Marqueste C, Wazaefi Y, Bruneu Y, Triller R, et al. Ugly Duckling Sign as a Major Factor of Efficiency in Melanoma Detection. JAMA Dermatol, 2017;153(4):279-284. Population: 2,089 clinical images of nevi from 80 patients (and 766 dermoscopic images from 30 patients), assessed by 9 dermatologists. DOI: https://doi.org/10.1001/jamadermatol.2016.5500. Finding as used: all melanomas were labeled ugly duckling nevi; specificity of intrapatient comparative analysis was 0.96 (clinical images) versus 0.88 for lesion-focused analysis; using both reduced the number of nevi considered for biopsy by a factor of 6.9. ↑︎
[5] American Academy of Dermatology. Basal cell carcinoma: From symptoms to treatments (last updated October 1, 2025). https://www.aad.org/public/diseases/skin-cancer/basal-cell-carcinoma (accessed 2026-10-09). Finding as used: appearances of basal cell carcinoma (firm round raised growth, dip in the center, scaly patch, non-healing sore, scar-like mark, shiny bumps; shiny pink or red on lighter skin, brown or black on darker skin); slow growing, rarely spreads, can grow deep; pictures cannot rule in or out skin cancer. ↑︎
[6] American Academy of Dermatology. Squamous cell carcinoma: From symptoms to treatments (last updated January 13, 2026). https://www.aad.org/public/diseases/skin-cancer/squamous-cell-carcinoma (accessed 2026-10-09). Finding as used: appearances of squamous cell carcinoma (rough scaly patch, firm dome-shaped growth, sore that does not heal, wart-like or horn-like growth, change to a scar); possible pain, tenderness, itch, numbness or stinging, though some people feel nothing. ↑︎
[7] American Academy of Dermatology. How to check your nails for melanoma (last updated 5/7/21). https://www.aad.org/public/diseases/skin-cancer/types/common/melanoma/nail-melanoma (accessed 2026-10-09). Finding as used: melanoma can develop under and around the nails; signs are a dark streak, darker skin next to the nail, nail lifting, nail splitting, and a bump or nodule under the nail. ↑︎
[8] American Academy of Dermatology. Signs that could be melanoma on your foot. https://www.aad.org/public/diseases/skin-cancer/types/common/melanoma/signs-foot (accessed 2026-10-09). Finding as used: for people of African or Asian ethnicity, hands and feet are the most common places for melanoma; a prior foot injury may increase risk; foot melanoma can appear as a vertical dark line under a toenail, pinkish-red spot or growth, rapidly growing mass, or non-healing sore. ↑︎
[9] American Academy of Dermatology. Skin cancer in darker skin tones (last updated 6/3/25). https://www.aad.org/public/diseases/skin-cancer/darker-skin-tones (accessed 2026-10-09). Finding as used: skin cancer is often found later in people with darker skin tones but can be found earlier; dermatologists recommend learning the warning signs, checking your skin, and seeing a board-certified dermatologist for anything that looks like skin cancer. ↑︎
[10] American Academy of Dermatology. How to perform a skin self-exam (last updated 5/15/23). https://www.aad.org/public/diseases/skin-cancer/find/check-skin (accessed 2026-10-09). Finding as used: the full-length mirror, forearms/underarms/palms, legs/toes/soles, and hand-mirror steps for neck, scalp, back and buttocks; the body mole map for documenting the exam; make an appointment with a board-certified dermatologist for a new spot, a spot different from others, or a spot that changes, itches or bleeds. ↑︎
[11] National Cancer Institute, Surveillance, Epidemiology, and End Results (SEER) Program. Cancer Stat Facts: Melanoma of the Skin. https://seer.cancer.gov/statfacts/html/melan.html (SEER 21 registries excluding IL, 2016-2022, all races, both sexes; accessed 2026-10-09). Finding as used: 77% of cases diagnosed at the localized stage with 5-year relative survival of 100.0%; 5% diagnosed at the distant stage with 5-year relative survival of 34.0%. ↑︎
Kurt Greiner
Kurt is a digital strategist and IT professional blending emerging technology with practical application to help businesses and individuals streamline their digital presence. His current work focuses on the intersection of intentional living and technological resilience, exploring how individuals can leverage modern tools to navigate the second half of life with purpose.
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