The thigh is an unusual place for skin cancer as it doesn't get much sun.
I've had 2 skin grafts on my scalp 13yrs ago for BCC and SCC in situ. Both not particularly serious unless not treated for several years.
I was urgently referred last year by a nurse from a photo I took. The dermatologist said I should never have been referred as a GP would have known it's a whatsamacallit and would fall off. It did. There are dozens of conditions that all look very similar and are often caused by sunshine.