What are your recommendations for a patient with metastatic non-mutated lung adenocarcinoma who previously had headaches responsive to prednisone but with negative temporal artery biopsy for GCA?  

GCA is often a challenging diagnosis to make in the absence of objective findings of halo sign, pathologic evidence of vasculitis, or large vessel vasculitis on imaging. Headache of any type will often respond to prednisone so the first step, in this case, is to determine if the patient truly has GC...