In the shower one day, long-term Tokyo resident Neil Grainger noticed that the birthmark on his back had changed color. Concerned, he went to the local clinic, but the doctor assured him it was nothing to worry about.

Three or four months later, the mole began to bleed. "I could only wear dark-colored shirts in case it bled during the day," he says. "If I banged into something, I would get blood on my shirt."

The 44-year-old Briton then went back to the doctor, and on July 17 last year, after undergoing a series of tests, he was diagnosed with a malignant melanoma.