Bronchiolitis, an update

Besides the classical forms of acute and chronic bronchiolitis, different s pecial forms, such as obliterative, respiratory, and follicular bronchiolit is are recognized. In addition, even new entities emerge, such as Sauropus- induced bronchiolitis. Despite this progress in pathology, pulmonologists s till prefer the diagnostic term 'small airways disease', instead of the mor e specific and even etiology-directed diagnoses provided by the morphologic examination. In this overview, an updated classification will be presented , which includes all forms of bronchiolitis described so far. This classifi cation is structured along morphologic features of bronchiolitis. Different forms of acute and chronic bronchiolitis are described, so that a given re action pattern can be associated with specific causes, such as eosinophilic bronchiolitis in asthma, or necrotizing bronchiolitis in viral infection. However, there exist more than just one morphologic reaction for a given et iologic agent, resulting in an overlap of morphologic appearances for a giv en disease.