Having a biopsy on my Thymus Gland but is it NECESSARY?

Hi this is Sandra, 19 years old.
I know i've put many post concerning the thymus gland.
I've been very frustrated with my primary care doctor. She wouldn't listen any of my symptoms and just assume everything and I know she can't know everything but not listening to her patients is just beyond frustrating and annoyed. 

I've been diagnosed with grave's disease july 2011 and i've got radioactive iodine to destroy the thyroid in April 2012. I've did my blood test last week and said my tsh and Free T4 is all normal (thankfully) but I've got my ct scan last week due to abnormalities in the center of the chest which chest x ray wasn't good enough so I went to do ct scan and said my thymus gland was enlarged. According to my primary care doc she said that it was due to Grave's disease so I wasn't really worried until she kept saying that I should go to the thoracic surgeon to get some advice and I kept asking what advice? and she said just to consider to do biopsy. But this is the point where I don't get. She said my thymus gland was due from my graves disease and I didn't know why she wanted me to go to the thoracic surgeon to talk about biopsy. Furthermore that I wasn't aware of. So is it necessary to do biopsy? I know I should talk to the surgeon but I didn't want to go there without absolute knowledge on the reason for visiting the surgeon. Just didn't want to be dumbfounded. 

So is it necessary? 

Thanks,
Sandra