Valley Fever can show up as biologically active cells on a PET scan, but the PET scan alone is not enough to differentiate which disease is present. In my case my doctors thought I had lung cancer as it would look the same on a PET scan. Valley Fever can mimic lung cancer on both CT scans and PET scans. Either a blood test or a biopsy is necessary to determine the specifics. A blood test is less invasive, but the test isn't always sensitive enough to pick up the cocci fungus (coccidioidomycosis), and often needs to be repeated. The biopsy results can definitively determine if you have Valley Fever, lung cancer, or something else. In my case part of my lung was removed under the assumption I had lung cancer, only to find out that what I actually had was Valley Fever. Surgery would probably not have been indicated for me, and the antibiotics I had taken to clear up the pneumonia I had previous to the surgery, didn't help. If you have a bad case of Valley Fever, you need an anti-fungal medication.
