Bronchiolitis obliterans with organizing pneumonia (BOOP) is characterized histologically in the lung by

Bronchiolitis obliterans with organizing pneumonia (BOOP) is a nonspecific reaction to multiple infectious or inflammatory lesions of the lungs. Causes of BOOP include infections (viral and bacterial), chemical toxins, drugs, and collagen vascular diseases. The lungs respond to these agents, causing bronchiolar injury by forming loose, fibrous tissue within the bronchioles (bronchiolitis obliterans) and alveoli (organizing pneumonia). Patients present with cough and dyspnea, and chest x-ray reveals interstitial infiltrates. Patients usually improve gradually, but steroid therapy may be needed. In contrast, asteroid bodies in giant cells are a nonspecific finding but can be found in the noncaseating granulomas of sarcoidosis. Multiple rheumatoid nodules within the interstitial tissue can be seen with rheumatoid ahritis, or might be pa of Caplan's syndrome. Numerous eosinophils within the walls of the alveoli can be seen in patients with asthma. Bronchiolitis obliterans showing intra-alveolar fibroblastic plugs filling the alveolar lumens. Reference: Robbins & Cotran Pathologic Basis of Disease, 9edition.