| ICD9 = | }} Pervasive Developmental Disorder - Not Otherwise Specified (PDD-NOS)'s one of the pervasive developmental disorders and autism spectrum disorders. PDD-NOS's a diagnosis for people who're well-described by the "PDD" label, but can't be categorized by any other disorder. It's usually milder than autism and has similar symptoms to autism, with some symptoms present, and others absent. This disorder's sometimes called "atypical autism" by autism specialists. The boundaries between PDD… (More on Pdd-nos)