High Quality Content by WIKIPEDIA articles! Diffuse panbronchiolitis (DPB) is an inflammatory lung disease of unknown cause. It is a severe, progressive form of bronchiolitis, which is inflammation of the bronchioles, small air passages in the lungs. The term "diffuse" refers to the lesions that appear throughout both lungs, while "panbronchiolitis" refers to the inflammation found in all layers of the respiratory bronchioles (the section of the bronchioles involved in gas exchange). DPB causes severe inflammation of the respiratory bronchioles, nodule-like lesions in respiratory and terminal bronchioles, chronic sinusitis and intense coughing with large amounts of sputum production.