A woman who thought a streak that had been growing on her nail for years was "cool" was horrified to be told what it really was.
Maria Sylvia said she first noticed the dark brown mark ten years ago - but thought nothing of it, as she was "in and out of doctors all the time" due to being an athlete.
The Tik Toker - who has more than 15,000 followers - shared the news online after finding out it had "probably been cancerous for the last three years". Doctors tol her it was subungual melanoma, a serious form of skin cancer that takes hold in the skin under your nails
She said on her page @invrfoundwaldo : "No one really noticed it until one time a doctor did notice it. This was probably circa 2014, and they were like, 'oh, that's odd'. But you don't really fit the demographics".
Maria, from the US, was offered surgery in which doctors removed her nail and part of the bone.
She said: “Melanoma can sit in a stage called in situ, which is kind of like stage zero, for up to 13 years.
“So it's very likely that this has just been sitting for 10 years and it's been maybe cancerous for the last three, it's kind of hard to tell.”
When she woke up she had a cast covering her entire hand and stopped her thumb from moving as it recovered.
Maria's thumb was given a skin graft, with doctors taking flesh from her arm. She's now waiting to see what the final result will look like.
He video, which has reached 14 million people, has left viewers worried about their own similar streaks.
Medical advice warns that you should go and see a doctor if you see a change in size, colour, or shape of the nails.
If your nail separates from the nail bed, bleeds, thins or cracks or has a bruise that won't go away - it could be a sign something is wrong.
Melanoma is the worst form of skin cancer and is usually caused by eexposure to UV rays.
But caught early, it has a good survival rate with 90 per cent of people surviving if the cancer is detected at stage one.
There are still more than 2,000 melanoma skin cancer deaths in the UK every year.
