Sun spots are small, sharply edged tan or brown marks that appear on sun exposed skin and stay roughly the same shape for years. Melasma is a soft, blotchy, often symmetrical brown patch driven by hormones plus UV. Post inflammatory hyperpigmentation is a flat brown mark left behind by something that already healed, like a pimple or a scratch. And one more thing lives in this category, looks deceptively similar, and is a skin cancer that must not be missed: melanoma. This page is the side by side, with the safety line drawn clearly.
For the complete picture on sun spots specifically, see our full sun spots guide. This page is the identification question.
Key takeaways
The edge, the symmetry, the trigger, and the safety flags route you correctly.
- Sun spot: sharp edged tan to brown mark, 2 to 20 mm, on sun exposed skin, stable for years.
- Melasma: soft mirrored brown patch on cheeks, forehead, or upper lip, hormone driven.
- Post inflammatory hyperpigmentation: brown echo of a prior pimple or wound, fades on its own.
- Melanoma (the dangerous mimic): asymmetric, multi colored, changing, or bleeding pigmented lesion.
- If you are not 100% certain, see a dermatologist before any at-home treatment.
Why this cluster gets misidentified so often
Brown patches on a 40 plus face are common, and three very different conditions show up in roughly the same zone. A sun spot on the temple, a melasma patch on the cheek, and a post acne mark on the jawline can all read as "brown spots" in the bathroom mirror, especially under warm lighting.
The misidentification problem matters because the treatment paths split sharply. Sun spots respond well to plasma energy used at the surface. Melasma is hormone driven and is often made worse by heat based devices, which is why dermatologists treat it with topicals and laser settings designed not to heat the dermis. Post inflammatory hyperpigmentation usually fades on its own over several months and does not need a device at all. And melanoma needs a dermatologist, full stop.
Identification is the gate before treatment. Get it right and the routing is simple. Get it wrong and you can either waste time on a device that will not help, or worse, delay a dermatologist visit that mattered. For context on why these marks appear suddenly in the first place, see why am I suddenly getting sun spots.
Side by side: the comparison table
Read this once, then we will walk through the cues in plain English. The sun spot column is highlighted because the rest of this cluster goes deeper into that condition. The melanoma column is marked in red because it is the one row on this page that is not a candidate for any at-home pathway.
The sun spot column is the only column on this page where an at home plasma pen device is appropriate. Three of the four columns route elsewhere.
How to tell sun spots from melasma
This is the most common confusion on the cluster, because both sit on the face and both look brown.
The best cue is the edge. Sun spots have sharp, defined edges. You can almost trace the outline with a fingertip. Melasma is soft and blotchy, with edges that blur into the surrounding skin rather than ending in a clean line. The Mayo Clinic describes melasma as patchy and irregular for this exact reason.
Symmetry helps too. Melasma very often shows up as mirrored patches across both cheeks, both sides of the forehead, or the upper lip moustache zone. Sun spots are scattered. They might cluster in sun exposed zones but they do not arrange themselves symmetrically on the face.
Trigger is the deciding cue. Melasma is hormone driven (pregnancy, birth control, peri menopause) and is set off and worsened by UV and heat. Sun spots are purely a UV history problem and do not flare with hormones.
If you see a sharp edged tan to dark brown spot on the temple, hand, or chest that has been there for years and looks the same shape, lean sun spots. If you see a soft mirrored brown patch on both cheeks or the upper lip that came on during pregnancy or hormone changes, lean melasma and see a dermatologist first. For more on location specific reading, see our pages on sun spots on the face and sun spots on the chest and decolletage.
How to tell sun spots from post inflammatory hyperpigmentation
Post inflammatory hyperpigmentation, often shortened to PIH, is the brown mark left behind by something that already healed. A pimple, a bug bite, a scratch, a burn. NIH MedlinePlus groups it under pigmentation disorders driven by inflammation.
The trace cue is whether you can remember the cause. PIH almost always sits exactly where a prior breakout, wound, or rash was. The shape often matches: round if a cyst was there, linear if a scratch was there, irregular if eczema or a burn was there.
Sun spots do not have a "trigger event" that you can name. They appear gradually in zones with cumulative UV exposure and were not preceded by inflammation.
Time is the other cue. PIH typically fades on its own over three to twelve months with sun protection and gentle skincare. Sun spots stay the same shape and color for years. If a brown mark you noticed last summer is meaningfully lighter this summer, that is PIH behavior, not sun spot behavior. For comparison reading on what does fade on its own, see do sun spots go away on their own.
The one you must never miss: melanoma mimics
Melanoma is the most serious skin cancer because it spreads. Caught early it is highly treatable. Caught late it is not. The American Academy of Dermatology teaches the ABCDE rule as the standard self check, and it is worth memorizing.
Pigmented lesions are exactly where it hides. Five cues that point to melanoma and away from any of the three benign conditions on this page:
- Asymmetry. Sun spots are usually round or oval and roughly symmetrical. A pigmented spot where one half does not match the other is a flag.
- Border. Sun spots have a clean edge. A spot with notched, jagged, or blurred borders is a flag.
- Color. Sun spots are uniform tan to brown. A spot with multiple colors mixed together (brown, black, red, white, blue) is a flag.
- Diameter. Anything larger than about six millimeters (the size of a pencil eraser) deserves a closer look. Sun spots can occasionally be larger but should still be uniform and stable.
- Evolving. A spot that is changing in size, shape, color, or texture over weeks or months needs a dermatologist promptly.
If any of those five cues is present, stop the at home identification process and book a dermatologist. The cost of getting it wrong here is meaningful.
A sharp edged tan spot that has stayed the same shape for years is almost always a sun spot. A pigmented lesion that is asymmetric, multi colored, or changing is not. That is the line, and it is the only line that matters before you reach for a device.
When you can treat at home
Only one of the four conditions on this page has an at home pathway: confirmed sun spots, in a clearly visible location, with none of the melanoma flags above and no overlap with a hormonal melasma pattern.
That means all of the following are true:
- The mark is tan to dark brown with a sharp, defined edge.
- It is on a sun exposed area (face, hands, chest, shoulders) and has been there for months or years without changing.
- It is not part of a symmetrical patch across both cheeks or the upper lip.
- It does not bleed, does not itch, and has not changed in size, shape, or color recently.
- It passes the ABCDE check.
If all of those are true, the at home pathway for sun spots is the OcuraLife plasma pen, used at a low to moderate power setting on the spot itself, followed by the aftercare protocol covered in our at home sun spots removal guide and our deeper best at home sun spot removal method. Treatment takes about 5 minutes per spot, with a small protective scab forming on Day 1, falling off naturally between Day 3 and Day 7, and clear skin visible by Week 2 to Week 3. The device offers 9 adjustable power settings for different spot sizes and depths.
For a head to head on the alternatives, see plasma pen vs vitamin C vs retinol for sun spots. If any one of the identification conditions above fails, the at home pathway closes and the next step is a dermatologist.
When in doubt, see a dermatologist
If you are not 100% certain, see a dermatologist before any at-home treatment. The plasma pen is for confirmed sun spots only, never for moles, never for uncertain pigmented lesions, and never for any spot with melanoma flags. Specifically, book a dermatologist if:
- The mark is asymmetric or has notched, blurred, or uneven borders.
- It contains multiple colors mixed together (brown plus black, plus red, plus white).
- It is larger than about six millimeters and growing.
- It is changing in size, shape, color, or texture over weeks or months.
- It bleeds, itches, or crusts spontaneously.
- It looks like a soft, mirrored brown patch across the cheeks, forehead, or upper lip (a melasma pattern, which should NOT be treated with at home heat based devices).
- It appeared during pregnancy, on birth control, or during peri menopause and is symmetrical.
- You simply are not sure.
The bottom line
Sun spots are sharp edged, stable, UV driven, and respond to surface treatment. Melasma is soft, mirrored, hormone driven, and is made worse by heat. Post inflammatory hyperpigmentation is a fading echo of a prior breakout or injury and usually does not need a device. And melanoma is the one that hides in the same color family, breaks the ABCDE rules, and needs a dermatologist's eye.
The plasma pen is appropriate for one of those four conditions, and only when the identification is clean and the safety flags are absent. For anything else, the next stop is a doctor. For the full pillar context, see our sun spots complete guide and the closely related age spots pillar (the two terms overlap medically and are often used interchangeably for the same lesion). If your sun spots seem to be clustering more in mid life, see sun spots after 40.
Related guides in this series
- Sun Spots: The Complete Guide to UV-Triggered Pigment (the pillar)
- How to Get Rid of Sun Spots at Home
- Why Am I Suddenly Getting Sun Spots?
- The Best At-Home Way to Remove Sun Spots in 2026 (the bridge brief)
- Sun Spots on the Face: Why and What To Do
- Sun Spots on the Chest and Decolletage
- Plasma Pen vs Vitamin C vs Retinol for Sun Spots
- Sun Spots After 40: Why They Cluster Now
- Do Sun Spots Go Away on Their Own?
Outbound references: American Academy of Dermatology, NIH MedlinePlus on pigmentation disorders, Mayo Clinic on melasma.
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Delivers focused plasma energy at the surface of the spot. 9 adjustable power settings, single-use sterile tips. A small scab forms, falls off on its own between Day 3 and Day 7, and clear skin is visible by Week 2 to Week 3. For confirmed sun spots only, never for pigmented moles, never for uncertain lesions, never for any mark with melanoma flags.
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