It's been a long time since your post, but this may interest you. I had a carotid body tumor excised 15 years ago. It nested in the bifucation of the carotid artery, and stuck out of my neck right next to my adam's apple. Mostly painless, but pushed uncomfortably on my windpipe when turning my head. Was told they were always benign.
Fast forward to 2003. Routine chest x-ray reveals metastatic disease widespread throughout lungs and spine. After many more scans and biopsies and much discussion, the consensus is that this is a metastases of that carotid body tumor.
So stay vigilant and research as much as you can about what your pathologist's report says.