Heterogeneity represents a keyword in most epidemiological studies on Pediatric Multiple Sclerosis (PMS). In fact, depending on study results, the Pediatric Multiple Sclerosis (PMS) annual incidence varies from 0.15 up to 3 per 100000 children, the female to male ratio from 1.2 up to 4.5 and the percentage of pediatric-onset compared to adult-onset (MS) ranges from 1.6 up to 9.5%. In particular, Pediatric Multiple Sclerosis (PMS) represents one of the future outcomes of an Acquired Demyelinating Syndrome (ADS) among children none the less; its proportion at Acquired Demyelinating Syndrome (ADS) onset is also a matter of debate.