There is no clever technology at the centre of this. A trained eye compares every spot on your skin against the others and looks for the one that does not belong — the ugly duckling. Melanoma and other skin cancers usually look different from a person's other moles, and that comparison is easier for someone looking at your whole skin at once than for you looking at one spot in a mirror.
When something needs a closer look, the dermatologist uses a dermatoscope: a magnifier with a light that touches the skin and lets them see the pigment and blood vessel patterns just below the surface. Most spots are settled at that point without anything being cut. If a spot still looks wrong, a small sample is taken and sent to a laboratory, because that is the only way to know for certain.
The other thing the appointment produces is a baseline. Photographs, notes and measurements of what your skin looked like on a given day. Change over time is the strongest signal in skin cancer detection, and change can only be judged against a record of what was there before. A first appointment is less useful than a second one for exactly this reason.
Take off nail polish and gel from fingers and toes. Melanoma can start under a nail, and polish hides it. This is the single most common reason part of an exam gets skipped.
Leave makeup off, or expect to remove it. The face is a common site.
Skip self-tanner for a week or two if you can — it makes it harder to assess colour.
Wear your hair down and unstyled rather than in a tight braid or heavily gelled, so the scalp can be parted and looked at.
A list, or photographs on your phone, of the spots you are worried about. Say these first — do not wait for them to be found.
Any history of skin cancer in your family, and roughly when.
A list of your medicines, particularly anything that suppresses your immune system.
Say so at the start. It is a common thing to be anxious about and a normal thing to mention.
You can ask for a chaperone. Most clinics offer one as standard and all should accommodate it.
You can ask the dermatologist to say what they are looking at as they go. Many people find the silence harder than the exam.
You undress to your underwear and put on a gown. You keep your underwear on. Anything you want examined underneath it is looked at with the gown adjusted, a section at a time, and you are covered the rest of the time.
The dermatologist works in a systematic order, usually starting at the scalp and working down. They are looking at everything, quickly, and pausing where something needs attention.
The scalp is parted and looked through. The face, ears, and behind the ears. The neck, chest, back, arms, palms and fingernails.
The legs, then the soles of the feet, between the toes, and the toenails. These are looked at deliberately, not as an afterthought — acral melanoma occurs on the palms, soles and under the nails, and it is the type most likely to be missed and most common in people with brown and Black skin.
The genital area and buttocks are usually offered rather than assumed. You can decline. If you have a spot there, say so — it will not be found otherwise.
When a spot needs a closer look, the dermatoscope is placed against the skin. It is a magnifier with a light. It touches the skin, sometimes with a drop of gel or alcohol, and it feels like nothing.
If a spot needs a sample, the area is numbed with an injection that stings for a few seconds, then a small piece is taken. You feel pressure, not cutting.
The whole exam usually runs ten to fifteen minutes. Nothing about it hurts.
There is nothing to recover from. You get dressed and go back to your day.
If a biopsy was taken, you leave with a small wound, a dressing and instructions. Keep it covered and moist with plain petrolatum, and expect it to heal over one to two weeks. It will leave a small mark.
Biopsy results usually take about one to two weeks. Ask before you leave how you will be told and when to chase it if you have not heard. Results getting lost in a system is more common than it should be, and following up is reasonable.
If nothing was biopsied, ask what you should watch for and when to come back. A useful appointment ends with you knowing which spots are being monitored.
Most appointments end with nothing found. That is the ordinary outcome and it is a useful one.
If a spot is biopsied, results usually come back in one to two weeks. Most biopsies are benign.
What you should leave with: a plan. Whether you need to come back, when, and which specific spots are being watched.
The value builds over time. The first exam mostly establishes what your skin looks like. The second, a year later, is where change can be judged — and change is the thing that matters most. If you can see the same dermatologist, or the same practice with the same records and photographs, do.
A clear exam is not a guarantee for the year ahead. Melanoma can appear and grow between appointments, which is why checking your own skin every month or two is part of the plan rather than an alternative to it.
Checking your own skin is genuinely useful, and it is the part that happens between appointments. Every month or two, in good light, with a hand mirror for your back, or with someone else's help. Include your scalp, the soles of your feet, between your toes and your nails.
What you are looking for is not a catalogue of shapes to memorise. It is two things: anything new, and anything changing. A spot that looks different from all your other spots, or a spot that has changed in size, shape or colour over a few months, or one that bleeds or will not heal. That is the whole brief. Photographs on your phone, taken with a ruler or coin for scale, make change much easier to judge later.
What a self-check cannot do is settle whether a spot is dangerous. Your job is to notice, not to diagnose. Deciding at home that something is probably fine is the most common reason a melanoma is found late.
Smartphone apps that claim to assess moles are not a substitute. Their accuracy varies widely, most are not regulated as medical devices, and a reassuring result from an app has talked real people out of getting real melanomas looked at. Use your phone to take photographs for comparison, not to get a verdict.