Clinical spectrum of adult chronic bronchiolitis

Inflammation involving the small airways is a quite common report in pathol ogical dissertations. However the radiologic, clinical patterns and functio nal impairment of adult bronchiolitis have been discussed in detail only in the last ten years. In this review a brief summary of the anatomic and his tologic characteristic of small airways is reported. A pathologic classific ation of bronchiolitis is at first discussed. Cellular bronchiolitis, proli ferative bronchiolitis with or without intraalveolar loose fibrosis (BOOP p attern), occlusive and constrictive bronchiolitis are the main patterns tak en into account: peculiar subtypes (follicular bronchiolitis, diffuse panbr onchiolitis, neuroendocrine cell hyperplasia with fibrous bronchiolitis) ar e included in the pathologic discussion. Radiologic features are reported a nd presented as nonspecific. HRCT Scan findings are classified with the app ropriate pathologic features in: nodules and branching lines; low attenuati on and mosaic perfusion; ground glass attenuation and/or alveolar consolida tion. The clinical entities considered are: bronchiolitis secondary to irri tant inhalation; infectious and post-infectious bronchiolitis; drug induced bronchiolitis; bronchiolitis in patients with collagen-vascular disease; d iffuse panbronchiolitis; bronchiolitis in transplanted patients; neuroendoc rine cell hyperplasia with fibrous bronchiolitis: cryptogenic bronchiolitis ; idiopathic BOOP; respiratory bronchiolitis with interstitial lung disease (RB-ILD). Their clinical presentation, functional impairment, pathogenetic mechanisms when deemed clinically useful, BAL findings and therapeutical s chemes are discussed.