A 78-year-old man had fever, persistent wheezing, and serum C-reactive protein elevation. Malignant lymphoma was suspected because of mediastinal lymph nodes swelling on CT and soluble interleukin 2 receptor elevation. Symmetric 18F-FDG uptake in the tracheobronchial tree and bilateral auricles was observed on PET/CT. He was finally diagnosed as having relapsing polychondritis by auricular cartilage biopsy. 18F-FDG PET/CT may have crucial role in evaluating the extent of inflammation and deciding the biopsy site of relapsing polychondritis.