Nicky,
Just want to reassure you that you shouldn't even have a thymus left after about age 30, so no trouble loosing the thing if it's causing problems!

As Erin said, the good news is that once they get that bugger out you should be on your way to recovery and quite possibly remission, so try to look on the bright side. You can get through the surgery just fine - if you can do the less invasive go for it!

We're all pulling for you! Best of luck for an easy operation and speedy recovery!