Seminars in respiratory and critical care medicine
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Semin Respir Crit Care Med · Oct 2003
Bronchiolar disorders: classification and diagnostic approach.
Bronchiolitis is a process in which inflammatory cells and mesenchymal tissue are both present, mainly centered in and around membranous and/or respiratory bronchioles, with sparing of a considerable portion of the other parenchymal structures. The distribution and amounts of the cellular and mesenchymal components vary from case to case, which accounts for the variety of histopathologic, radiographic, and clinical aspects of bronchiolitis. The clinical classification of bronchiolar diseases considers the causes or the clinical settings in which bronchiolitis develops: inhalation of toxic fumes, irritant gases or organic dusts, infectious and postinfectious bronchiolitis, collagen-vascular disease-associated bronchiolitis, posttransplant bronchiolitis, or rarer associations. ⋯ High-resolution computed tomographic scanning (HRCT) is currently the best imaging technique for the evaluation of patients suspected of having bronchiolitis. HRCT findings in bronchiolar diseases with a good correlation with histopathologic changes are classified as follows: centrilobular tubular branching or nodular opacities; ground-glass attenuation or consolidation; mosaic perfusion; a mixed pattern. This article presents and briefly discusses the diagnostic approach to these diseases.
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Organizing pneumonia is defined by the presence of buds of granulation tissue (fibroblastic cells and connective matrix) within the alveolar lumen, usually associated with proliferative bronchiolitis obliterans. It may result from several causes, but cryptogenic organizing pneumonia is a distinct clinicopathologic entity with characteristic clinical and imaging features. Typical COP is thus easily recognized by the clinician, and the diagnosis is made by the finding of organizing pneumonia on lung biopsy specimen. The response to corticosteroids is rapid and complete usually without sequelae, but relapses occur frequently and prolonged corticosteroid treatment is often necessary.
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Inflammatory and fibrotic processes can involve the small airways (i.e., respiratory and terminal bronchioles) in several connective tissue disorders (CTDs). Obliterative (constrictive) bronchiolitis (OB) as well cryptogenic organizing pneumonia (COP), previously termed bronchiolitis obliterans with organizing pneumonia (BOOP), are well-recognized, albeit rare, complications of rheumatoid arthritis and other CTDs. Bronchiectasis has also been described in patients with CTDs. ⋯ Surgical (open or thoracoscopic) lung biopsies can substantiate the diagnosis, but in some cases, the diagnosis can be affirmed less aggressively by appropriate imaging studies (e.g., HRCT) and transbronchial lung biopsies. Corticosteroids are highly efficacious for COP, but therapeutic options for OB are disappointing. Prophylactic antibiotics and good pulmonary hygiene remain the mainstay of therapy for patients with bronchiectasis.
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Semin Respir Crit Care Med · Aug 2003
Fibrotic idiopathic interstitial pneumonia: high-resolution computed tomography considerations.
The fibrotic idiopathic interstitial pneumonias comprise usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP). The characteristic high-resolution computed tomography findings of UIP are reticular abnormality and honeycombing with basal and peripheral predominance. Honeycombing is the strongest predictor of UIP. ⋯ The CT finding of extensive ground-glass abnormality and some reticular abnormality, with basal and peripheral predominance, is strongly suggestive of NSIP. However, the CT appearances of NSIP overlap with those of UIP, organizing pneumonia (OP), and desquamative interstitial pneumonia (DIP), and biopsy may be necessary to sort this out. Other idiopathic pneumonias that may be associated with CT evidence of lung fibrosis include DIP, OP, acute interstitial pneumonia, and lymphoid interstitial pneumonia.
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Bronchiectasis is an abnormal dilation of bronchi, consequent to the destruction of their walls. It is included in the category of obstructive pulmonary diseases, along with chronic obstructive pulmonary disease (COPD), asthma, and cystic fibrosis. In approximately 50% of cases, bronchiectasis is associated with underlying conditions; in the remainder, known causes are not ascertainable (idiopathic bronchiectasis). ⋯ The cystic fibrosis gene is also associated with bronchiectasis due to rheumatoid arthritis and allergic bronchopulmonary aspergillosis. A few other genes have been investigated in idiopathic bronchiectasis, with negative results. Idiopathic bronchiectasis is, therefore, to be considered as an obstructive multifactorial disorder belonging to the category of cystic fibrosis monosymptomatic diseases (or CFTR-opathies), whose pathogenesis is influenced by environmental factors and other undetermined genes.