John I had the same thing happen, PET/CT showed up positive, doc had me take antibiotics and did the test again a month later. Followed it with a sonogram guided needle biopsy, came back positive.

But, remember, my case is different from yours, my scans were positive to begin with, they just didn't want to act on false positives, which is apparently more likely than false negatives even though both are possible.

A good thorough sonogram guided needle biopsy done by an experienced doc should be fairly reliable. Still probably not 100%, only dissection is that, but better than a needless surgery. Sometimes the sonogram itself will tell what's going on. Had that happen also, a bump under my chin that showed up negative in pet/ct, was going to have biopsied, and the sonogram showed it apparently wasn't anything of concern. That was 3 PET/CT's ago, and apparently it's still nothing of concern.

Would try for the second opinion though for piece of mind.