Thoracic cat scan feb 2012 showed enlarged thymus and swollen lymph nodes but was never told to follow up until now with diff dr. is this bad? cancer?

Can not tell: The mass and presence of lymph nodes is cause for some concern . The definitive diagnosis is made after tissue biopsy and microscopic evaluation by pathologist . I hope that the condition turn out to be benign . Good luck.

Possibly: You may need follow-up imaging and biopsy if the thymus or lymph nodes have increased in size. It is unusual to have a thymus enlargement in adulthood.