Does gianotti crosti come back? My 15 month was just diagnosed with it and it's starting to go away after 7 days. Anything I can do to prevent it?

PAS SYNDROME. Gianotti crosti or as it is called nowpapulovescicular acrolateral syndrome which was first described in 1957 in itally by dr gianotti is caused by few viruses and since it is not one virus, theoreticaly it can recur, but it is such a rare condition, the odds are against it.
Generally once. It is self limited and does not recur. It does not leave residual marks. Treatment with topical steroids will lessen symptoms and appearance until it resolves within 1 to several weeks.
Sometimes x 2. Gianotti-crosti is thought to be a reaction to an underlying problem, often a viral infection but sometimes other things. It can recur if the underlying problem recurs. Treatment (and prevention) involve identifying the underlying cause (which is not always possible) and treating that. The rash itself usually does not require treatment.