You’re looking at your thumb and there it is. A thin, dark line. Maybe it’s brown, maybe it’s blackish, or maybe it’s just a blurry smudge that won't grow out. You start scrolling. You’re looking for nail cancer photos to see if yours matches the scary stuff on the internet. It’s a rabbit hole. Honestly, most people just assume they slammed their finger in a door or that they have a "splinter hemorrhage" from some yard work they don't even remember doing. But here is the thing: subungual melanoma—which is the medical term for cancer under the nail—is a master of disguise. It doesn't look like a tumor. It looks like a pen mark.
It’s rare. Very rare. We are talking about maybe 0.7% to 3.5% of all melanomas globally. But because people don't know what to look for, it often gets diagnosed way too late.
What Nail Cancer Photos Actually Show You
When you look at nail cancer photos in a medical textbook or on a dermatology site like the American Academy of Dermatology (AAD), you aren't going to see a giant bulging growth most of the time. What you see is a "longitudinal melanonychia." That’s just a fancy way of saying a vertical stripe that runs from the cuticle all the way to the tip of the nail.
These stripes are tricky. If you have darker skin, having multiple stripes on several nails is actually pretty normal and usually benign. But if you have one single stripe on one single nail—especially the thumb, big toe, or index finger—that is when doctors start getting twitchy. The stripe in a melanoma case usually looks "messy." The edges aren't crisp. It might be wider at the base than at the tip. Sometimes the color isn't uniform; it might be light brown on one side and charcoal on the other.
Then there is the Hutchinson sign. This is the big one. If the pigment—the dark color—starts leaking onto the cuticle or the skin around the nail, that is a massive red flag. Real nail cancer photos often show this "bleeding" of color onto the surrounding skin. It’s not actual blood. It’s the cancer cells producing melanin where it shouldn't be.
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The "Bruise" That Won't Go Away
I’ve heard stories of people waiting a year to see a doctor because they were "sure" they hit their toe on a coffee table. A subungual hematoma (a bruise under the nail) and melanoma look identical to the untrained eye. But bruises grow out. As your nail grows at its glacial pace of about 3 millimeters a month, a bruise will move toward the tip.
Cancer stays put.
Actually, it doesn't just stay put; it often gets wider at the base. If you have a dark spot and three months later it's in the exact same spot relative to your cuticle, you need a biopsy. Dr. Amy Wechsler, a well-known dermatologist, often points out that any new or changing streak in a nail warrants a professional look. It’s not about being a hypochondriac. It’s about the fact that this specific type of cancer is notoriously aggressive because it sits so close to the bone.
Why We Miss It: The Pedicure Problem
A huge issue with diagnosing this early is nail polish. We cover things up. You get a pedicure, the technician sees a dark spot, they paint over it, and you forget it exists for another three weeks. This is why many podiatrists recommend "nail breaks" where you go a week without polish just to inspect the health of the nail bed.
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It’s also not always a dark line. About 20% to 30% of subungual melanomas are "amelanotic." That means they have no pigment. No brown. No black. They look like a pinkish nodule or a persistent "wart" that won't heal. They might bleed easily or cause the nail to split down the middle. If your nail is lifting off the bed (onycholysis) and there’s no obvious reason like a fungal infection, don't just pour tea tree oil on it and hope for the best.
The ABCDEF Rule for Nail Health
Doctors actually use a specific mnemonic for this. It’s not the standard ABCDE for skin.
- A is for Age: Most cases hit between 50 and 70 years old, and it’s more common in African American, Asian, and Hispanic populations.
- B is for Band: Look for a band that is brown or black and wider than 3 millimeters.
- C is for Change: Is the band getting wider? Is the border blurring?
- D is for Digit: The thumb is the most common site, followed by the big toe.
- E is for Extension: This is that Hutchinson sign I mentioned—pigment on the cuticle.
- F is for Family history: If your family has a history of melanoma, your risk profile changes completely.
The Biopsy Process is Kinda Intense
If you go to a dermatologist and they don't like what they see in your nail cancer photos (the ones they take for your file), they’ll suggest a biopsy. This isn't like a skin biopsy where they just "shave" a mole. They usually have to numb the finger completely and either take a "punch" biopsy through the nail or remove a portion of the nail to get to the tissue underneath.
It sounds scary. It’s definitely uncomfortable. But the alternative is letting a malignancy sit millimeters away from your bloodstream.
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Treatment Has Changed (For the Better)
In the past, the standard treatment for a confirmed nail melanoma was immediate amputation at the first joint. It was drastic. Today, surgeons like those at MD Anderson Cancer Center often use "functional surgery." If the cancer is caught early enough (in situ), they might only need to remove the nail unit and a few millimeters of skin, followed by a skin graft. You keep your finger. You keep your mobility.
But this only works if you catch it before it invades the deeper layers. Once it goes deep, the survival rate drops. That's why staring at those nail cancer photos and comparing them to your own hand matters. It’s one of the few cancers you can literally see with your own eyes if you know what you’re looking at.
Realities of Subungual Melanoma
You’ll see some people online saying it’s caused by UV lamps at the nail salon. There is zero hard evidence for that right now. Most nail cancers aren't caused by the sun; they are caused by genetics or trauma. Unlike the melanoma on your shoulder, the skin under your nail rarely sees the light of day. It’s a different beast entirely.
Also, don't freak out if you have thin brown lines on multiple nails. That is usually just "melanonychia striata," which is basically like having freckles under your nails. It's super common in people with darker skin tones. The "worry" factor goes up when it's one solitary, changing line on one solitary finger.
Immediate Steps to Take
- Document the spot. Take a clear, high-resolution photo today. Hold a ruler next to it.
- Remove all polish. Check every single nail, including your pinky toes.
- Wait and watch (briefly). Give it one growth cycle (about a month). If the spot moves with the nail and leaves a clean area behind it, it’s a bruise. If the spot is a "streak" that stays connected to the cuticle, it’s not a bruise.
- See a Specialist. Don't just go to a GP; go to a dermatologist. Ask them specifically about the Hutchinson sign.
- Request a Dermatoscopy. This is a non-invasive way for them to look at the pigment patterns through a high-powered magnifying lens before deciding on a biopsy.
Early detection of subungual melanoma has a nearly 95% five-year survival rate. If you wait until the nail starts breaking or the finger starts swelling, those numbers change fast. Stop scrolling through endless galleries of nail cancer photos and go get a professional opinion if your gut is telling you something is off. It is better to have a scarred nail bed from a negative biopsy than to ignore a streak that ends up being something much worse.