Large Vessel Vasculitis in a Patient Receiving G-CSF: A Possible Differential for Fever of Unknown Origin.

Large vessel vasculitis is a known but rare side effect of granulocyte colony-stimulating factor (G-CSF) therapy. We report a case of adenocarcinoma lung with pleural infiltration and mediastinal lymphadenopathy, who was treated with neoadjuvant chemotherapy and pegylated G-CSF. After three cycles, he developed a fever. He underwent F-18 fludeoxyglucose (FDG) positron emission tomography computed tomography for fever of unkwnown origin evaluation, which revealed a response to chemotherapy along with the appearance of FDG avid mural thickening in a few large arteries, suggesting a diagnosis of G-CSF-induced large vessel vasculitis.