Three major histologic patterns of bronchiolitis: obliterative bronchiolitis, follicular bronchiolitis, and diffuse panbronchiolitis, are reviewed in detail. These distinct patterns of primary bronchiolar injury provide a useful starting point for formulating a differential diagnosis and considering possible causes. In support of the aim toward a cause-based classification system of small airway disease, a simple diagnostic algorithm is provided for further subclassification of the above 3 bronchiolitis patterns according to the major associated etiologic subgroups.
Keywords: Bronchiolitis; Classification; Diffuse panbronchiolitis; Follicular bronchiolitis; Obliterative bronchiolitis; Restrictive bronchiolitis; Small airway disease.
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