Clean bill of health! The vet says he looks fantastic and does believe that it was just a histiocytoma.
There was an African Grey Parrot in the entry to the clinic. We walked in and she said "sit down dog. Don't be scared". It was hilarious! The receptionist says she is always repeating everything she hears int he waiting room. She said "you are a good dog. sit, stay". Just hysterical and really eased our tension! She barked and meowed too!