Help!

My 3 year old son was diagnosed with Pervasive Developmental Disorder, which is resulting in him having a severe speech delay, He's currently in preschool and receives speech therapy once a week. I was told by his doctor's that PDD as it is known is an umbrella term for Autism. When I asked what do I tell people that ask what is wrong with him, they said that I can tell people that he has Autism as they treat PDD as they would Autism....Only problem is I feel like I'm lying...Am I lying when I tell people he's Autistic?

I not familiar with this diagnosis.

Sounds like its links to autism spectrum disorders. Perhaps it is more like Aspbergers?