Gonna beat the dead horse here...never rely on a PET for a diagnosis. Only a biopsy can tell for certain if a spot that lights up is cancer.

After a biopsy of a neck mass led to an erroneously diagnosed case of oral cancer, J had bilateral lymph nodes lighting up on his PET. The RO and ENT didn't order a biopsy of those nodes (despite a second surgery being scheduled for a diagnostic tonsillectomy.) The nodes were from a residual infection. Staging and treatment were based on the false positive PET CT scan. Lots of unnecessary carnage followed. Lesson learned...actually, many of 'em.