PWS and differences in leg size

My son is 19 months old. He has a PWS on his upper thigh, left buttock and left scrotum. He was a very chubby baby. He is starting to slim down however his right leg (w/o PWS) looks bigger than his left. I am wondering whether I should be concerned. Given its location, I wasn't going to treat it however, now that I've read that they continue to grow and get thicker, and that they can lead to different size extremities, I question whether I should have it treated. I am not sure where to begin. My pediatrician is great but no expert in birthmarks. I live in Portland Oregon and didn't see any doctors in Oregon listed on the 'Find a Physician' page. Where should I start and are my concerns valid?

[nickbar]

Hello, I live right across the river from you in Vancouver. Yes, treatment is a good idea for his PWS. contact information for OHSU. Dr. Krol 1-503-494-9993 he is a pediatric derm. Dr. Ken Lee is the laser surgeon (dr. Krol's office can give you the number for him. Our son was treated there for a hemangioma. If you want specifics on these doctors you can email me at rinner@comcast.net

Corinne