The actress, who plays Audrey Roberts in the ITV1 soap, received a call from ITV's in-house medical centre last summer after a concerned fan emailed the show saying they had spotted a potentially cancerous mole.
"One of the nurses told me a viewer had emailed to say they had noticed a mole on my upper left arm and suggested I should get it checked out," Nicholls said. "My first reaction was, 'Oh, how sweet'. I hadn't noticed it getting any bigger and it didn't hurt. It was round and dark and the size of a small pen top."
A doctor measured the mole and told Nicholls to return a few months later. When she went back for a check-up, the mole had grown a quarter of an inch and the doctor noticed dark specks in it, according to The Mail on Sunday.
She was referred to skin cancer specialist and consultant plastic surgeon Stewart Watson at Manchester's Wythenshawe Hospital and later had the mole removed at the Alexandra Hospital in Cheadle, Cheshire. A week after the procedure, Watson confirmed that the mole had turned into melanoma.
"I undoubtedly would have left this mole were it not for that viewer," she added. "I would still be saying, 'Oh, I've had that forever' and not be giving it a second thought. But I'll never know to this day who emailed - I don't even know if it was a man or a woman."
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