Bronchial stenosis is an uncommon but potentially life-threatening complication of granulomatosis with polyangiitis (GPA). The development of lower respiratory tract stenoses in patients with GPA is thought to be the result of persistent inflammation of the cartilaginous tissue. New assessment methods for this severe GPA complication are highly needed. Herein, we show the value of 18F-fluorodeoxyglycose positron emission tomography/computed tomography (18F-FDG-PET/CT) in the diagnosis, prediction of progression to bronchial stenosis and response to treatment of endobronchial involvement in a patient with GPA.