Perschon was successfully treated for cancer at Children's.
"Drew was very excited. A little star struck as you can tell watching all of you perform with him. Thanks again and what you're doing means so much and we think of you every moment when you are at work. Thank you" said Kate Perschon, Drew's mom
The construction team signed hard hats that were given to Drew and his grandfather.
The new Ann and Robert Lurie Children's Hospital is expected to be completed in 2012.