PROLIFERATIVE AND CONSTRICTIVE BRONCHIOLITIS - CLASSIFICATION AND RADIOLOGIC FEATURES

The small airways of the lung consist of the terminal bronchioles, res piratory bronchioles, and alveolar ducts. A recently introduced pathol ogic classification system divides bronchiolitis into proliferative an d constrictive types [1]. The histologic classification of small-airwa ys disease into proliferative and constrictive bronchiolitis frequentl y correlates with the radiographic appearances. Proliferative bronchio litis is characterized by air-space opacification, whereas constrictiv e bronchiolitis tends to be associated with lobular areas of decreased attenuation and airway dilatation. The purpose of this essay is to il lustrate the radiographic and CT features of these two varieties of br onchiolitis.