Another said it could be harmless, writing: “I had one on my toenail recently. Went to the derm and confirmed it’s longitudinal melanonychia. For me, it’s apparently not concerning but something they want to keep an eye on and measure to make sure it’s not changing. Hope the same for you, Tough_Nips!”
According to Healthline, having a dark line on your fingernails or toenails can come from a condition called melanonychia – a type of melanoma skin cancer.
One woman narrowly escaped death after spotting a dark line on her thumb too, having been diagnosed with one of the most life-threatening forms of cancer.
Someone else wrote: “I had the exact same line spontaneously appear as a kid, saw my pcp who referred me to a dermatologist who recommended I biopsy it to be safe. They pulled back the skin behind my thumb for the biopsy that luckily confirmed that the mole was benign. Line went away after the biopsy.”
A fourth speculated: “I have one as well, same finger, same location. been there for over 10 years. Let us know what the Dr says! I saw a dermatologist a few years ago. she seemed rushed, looked at it through a tiny handheld magnifier, and told me not to worry. Then she left the room. I had to ask a nurse if she was done. Yes, she was done.”
The poster was quick to update everyone hours after posting, explaining that she was actually booked to see the doctor that day, writing: “Funnily enough, I have a regular check up today. Will definitely ask my GP.”
She then updated just one hour later with good news: “Update: Got a referral to a dermatologist today from my regular doctor. Just waiting for them to call me.”
As for what it could be, one person asked her if she happened to have a genetic condition, which could cause the tine to appear.
They asked her: “Do you have Thalessemia? It is a hereditary blood condition. It can cause these. Have also heard that other conditions which affect your liver can cause these to show up.”
To this, the OP confirmed: “I have thalassemia and also have the line, I didn’t know the condition caused it.”
