Most dangerous skin spots aren't caught at a single visit — they're caught because someone noticed a change. Here's how doctors actually evaluate a mole, and how you can borrow that same approach at home.
Why This Matters
In our last issue, we covered sun protection. But protection is only half the picture — early detection is the other half, and it's arguably the more important one. Melanoma, basal cell carcinoma, and squamous cell carcinoma are all becoming more common, and in nearly all cases, catching them early is what makes curative treatment possible.
Here's the reassuring part: most dangerous lesions aren't identified through some advanced test. They're identified because a patient (or their doctor) noticed a spot that looked different, or that had changed. That's a skill you can build.
The ABCDE Rule — and the "Ugly Duckling" Test
Dermatologists use a simple checklist to evaluate a mole. You can use the same one:
- A — Asymmetry: one half doesn't match the other
- B — Border: edges are blurry, ragged, or notched
- C — Color: more than one shade — light and dark brown, black, or red within the same spot
- D — Diameter: larger than a pencil eraser (about 5mm), though smaller melanomas do happen
- E — Evolving: changing in size, shape, color, or texture — or becoming raised
The one to weigh most heavily
Of all five letters, "E" — evolving — is the one worth taking most seriously. Any mole that's new, growing, bleeding, itching, crusting, or changing color deserves a prompt look, even if it doesn't check every other box.
There's also a useful shortcut beyond ABCDE: the "ugly duckling" sign. Most of your moles tend to look like siblings — similar size, shape, and color. A mole that stands out from the rest, even if it doesn't obviously break the ABCDE rules, is worth a second look.
Who Should Be Extra Vigilant
Everyone benefits from occasional self-checks, but you should be especially thorough — and check more often — if you have:
- Fair skin, or many moles (especially atypical-looking ones)
- A personal or family history of melanoma or other skin cancer
- A weakened immune system, or a history of organ transplant
- A history of significant sun exposure, sunburns, or indoor tanning
Don't forget easy-to-miss spots: the scalp (especially if hair is thinning), ears, back of the neck, forearms, backs of hands, and lower legs. Basal cell carcinoma in particular tends to show up on these sun-exposed areas, and can look deceptively harmless — a shiny bump, a small sore that won't heal, a pink patch, or a spot that keeps bleeding.
Track Changes, Not Just Snapshots
Many concerning lesions aren't obvious the first time you see them — they become obvious when you compare them to how they looked a few months ago. If you have several moles, it's worth taking a few photos (good lighting, in focus, maybe next to a coin or ruler for scale) every few months so you have something to compare against.
If you notice a spot has grown, changed color, developed a crust, started bleeding, or simply hasn't healed after a few weeks, that's your signal to get it looked at — not to keep watching it for another few months.
What You Can Actually Do
- Do a full-body self-check every 1–2 months. Use a mirror (or a partner) for hard-to-see spots like your back and scalp.
- Apply the ABCDE rule, and look for the "ugly duckling." A spot that doesn't match its neighbors is worth a second look, even if it seems minor.
- Don't wait out a changing spot. Rapid growth, bleeding, ulceration, pain, or a sore that won't heal in a few weeks all warrant prompt evaluation — not a "let's see how it looks next month" approach.
- Ask about a virtual visit if you're unsure. A clear photo — good lighting, in focus, with something for scale — can help us triage whether a spot needs an in-person exam soon or can be monitored. For anything genuinely concerning, an in-person exam and possible biopsy are still the gold standard.
- Get a baseline professional skin exam if you're high-risk, and don't skip your annual one after that.
The bottom line: Skin cancer is rarely caught by accident — it's caught by people who know what to look for and act on it. Learn the ABCDE rule, know your own moles well enough to spot the "ugly duckling," and don't sit on a changing or non-healing spot. Early evaluation is what makes these cancers so treatable.
Partnering in your care,
Dr. Kenji Taylor, MD
Torii Health & Iris Dental and Medical