Hi @skm101, A PET scan will show a mass, but it will also provide information on the amount of metabolic activity in those masses. Infections, inflammation, and cancer will all have metabolic activity. That activity lights up on the scan, and will show as different levels of brightness (or uptake). Cancer is very active, and will have a higher number.

A biopsy is a good next step. Your doctors are taking actions on what they are seeing, and are trying to make sure they don’t miss anything. Are they doing the biopsy through a bronchoscopy procedure?
https://www.mayoclinic.org/tests-procedures/pet-scan/about/pac-20385078