Bronchiolar Disorders

[[author photo]]This issue of Seminars is devoted to the complex topic of the bronchiolar disorders. The spectrum of causes and associated conditions of adult bronchiolitis is wide, ranging from the rather “benign” changes of respiratory bronchiolitis observed in almost every “healthy” cigarette smoker as an incidental finding on lung biopsy, to the severe and often life-limiting complication of posttransplant bronchiolitis obliterans.

During the last 2 decades our knowledge on small airways disorders has expanded greatly. Bronchiolitis obliterans with organizing pneumonia was recognized as a new chinicopathologic entity, new inhalational causes related to occupational exposures were identified, new associations with connective tissue and inflammatory bowel diseases were described, and a peculiar entity known as diffuse panbronchiolitis, first seen only in Asians, was also reported in Caucasians.

This issue provides the latest information in regard to the classification, pathophysiology, histopathology, and diagnosis of bronchiolar disorders. In terms of the latter, high-resolution computed tomography (HRCT) is currently the best clinical tool for diagnosing bronchiolitis, with good correlations between HRCT patterns and histopathologic disease classification.

Disease-specific sections discuss clinical presentation, diagnostic procedures, patient management, and prognosis. A multidisciplinary approach, combining clinical, radiological, and histopathologic expertise, is required in difficult cases. We hope that this issue will prove helpful in the diagnosis and management of these less common disorders.