How long does PRP last?

Here's a selection of information from patients & professionals to better understand Pityriasis Rubra Pilaris.

Answer

For that answer we must go back to the adult and juvenile classifications:
-Classic Adult Onset: 3-4 years, maybe less, maybe more
-Atypical Adult Onset: 20 years, maybe less, maybe more
-Classic Juvenile Onset: Spontaneous remission within a year or not
-Atypical Juvenile Onset: Persistent which seems to be chronic, long-term
-Circumscribed Juvenile Onset: Remission in late teens or not