Dad has had a few spots removed over the years, mostly head as he never wore a hat or used sun protection. Now he has a spot on his arm that appeared 2 weeks ago and he noticed it growing fast over the past few days. He is trying to get in touch with his dermatologist. Does melanoma appear fast? Does it grow fast? It is a dime size spot. He was at the dermatologist a few weeks ago and he said they would watch it but not to worry but now it is growing.
It did continue to grow and by the following week when she saw the dermatologist it was almost the size of a half dollar. He scheduled a biopsy at the hospital for the following day and said if need be it would be removed at the same time. As it turned out it was malignant and removed at that time. She is fine now, but is lucky it was in such a visible area to be spotted so quickly.
It is important to anyone, at any age, if you notice any sudden changes on your skin to be vigilant and get to a dr quickly. It could be nothing, but better to find out sooner rather than to late.
I wouldn't take a chance; if your father can't get in touch with his dermatologist, I'd make the call and get him in ASAP.
Hopefully it won't be melanoma, but best to find out about this new growth.