The main pathologic findings in respiratory bronchiolitis-associated interstitial lung disease are respiratory bronchiolitis, with lightly pigmented macrophages and mild inflammatory changes that are primarily centered on respiratory bronchioles.
American Thoracic Society/European Respiratory Society 2002 International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias (a) Histologic Pattern Clinical-Radiologic-Pathologic Diagnosis Usual interstitial pneumonia Idiopathic pulmonary Nonspecific interstitial fibrosis or cryptogenic pneumonia fibrosing alveolitis Organizing pneumonia Nonspecific interstitial Diffuse alveolar damage pneumonia (provisional) Respiratory bronchiolitis Acute interstitial pneumonia Desquamative interstitial pneumonia Respiratory bronchiolitis Lymphoid interstitial pneumonia interstitial lung disease Desquamative interstitial pneumonia Lymphoid interstitial pneumonia (a) Data adapted from American Thoracic Society; European Respiratory Society.
Membranous Bronchiolitis and Respiratory Bronchiolitis
Histologically, both membranous bronchiolitis and respiratory bronchiolitis contain cellular infiltrates made up predominantly of lymphocytes and histiocytes within the bronchioles and infiltrating into surrounding peribronchiolar tissue.
Patients with respiratory bronchiolitis histologically, who are typically heavy smokers, with generally mild nonprogressive symptoms of dyspnea and cough, and with radiologic changes of interstitial lung disease, are diagnosed as having RBILD.
Pulmonary Langerhans cell histiocytosis commonly arises within a background of respiratory bronchiolitis and should be considered as a possible concurrent disease process in patients with respiratory bronchiolitis.
The authors designated this finding peribronchiolar metaplasia-related interstitial lung disease because of the analogy with respiratory bronchiolitis and RBILD, in which respiratory bronchiolitis is a common incidental finding in smokers and RBILD is the smoking-associated clinically significant interstitial lung disease.
The concept of respiratory bronchiolitis/interstitial lung disease (RBILD) was introduced in 1987 by Myers et al (1) as a morphologic explanation for clinical interstitial lung disease (explicitly, in their article, restrictive pulmonary function tests and/or interstitial markings on plain chest radiographs) in 6 patients in whom nothing besides smoker's respiratory bronchiolitis (RB) could be found on surgical lung biopsy.
Respiratory bronchiolitis was first described by Niewoehner et al (10) in 1974 as a lesion seen in young cigarette smokers dying accidentally; their description included smoker's macrophages in bronchiolar lumens, fibrosis, and inflammation in the bronchiolar wall and, although this point has been somewhat ignored in descriptions of RBILD, variable amounts of fibrosis in the surrounding alveolar walls.
Clinical significance of respiratory bronchiolitis on open lung biopsy and its relationship to smoking related interstitial lung disease.
Pathologic Features Reported in Respiratory Bronchiolitis/ Interstitial Lung Disease (RBILD) and Respiratory Bronchiolitis (RB) Fibrosis/ Mild Fibrosis Inflammation Alveolar Walls Source, y in Walls of RB Around RB RBILD studies Myers et al, (1) 1987 + (fibrosis and + (also inflammation inflammation) and large alveolar lining cells) Yousem et al, (5) 1989 + +(mild only) Moon et al, (4) 1999 + Ryu et al, (6) 2005 Only smoker's ?
One of the primary, nonchronic, obstructive, smoking-related lung pathologies is respiratory bronchiolitis
interstitial lung disease, which was included in the diagnostic categories in the 2002 American Thoracic Society and European Respiratory Society consensus article (6) on interstitial lung disease.