This is why we need a platform for these models asap. I would totally download this app today and use it regardless of what the FDA thinks.
I say when it comes to medicine, err on the side of caution. Obviously a diagnosis app isn't too dangerous - worse case scenario the app gives you a positive diagnosis, so you go into the doctor's, they take a sample, and find the growth to not be cancerous. No harm, no foul. But other ideas could be more dangerous.