Seminars in respiratory and critical care medicine
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Patients with cystic fibrosis (CF) have an abnormal propensity for recurrent and chronic infections of the lower respiratory tract (LRT), and the most common cause of a shortened lifespan is chronic infection with Pseudomonas aeruginosa. A few other gram-negative organisms, primarily Burkholderia cepacia complex have, however, emerged as serious pathogens capable of establishing chronic LRT infection. Details of these and other CF pathogens can be found in the article by Dr. ⋯ Other more rare pathogens such as Stenotrophomonas maltophilia, Achromobacter xylosoxidans, and nontuberculous mycobacteria (NTM) appear less capable of causing patient-to-patient transmission. Both the physical proximity and the duration of exposure of noninfected patients to patients chronically infected with P. aeruginosa and B. cepacia complex are important determinants of the risk of cross-infection. Cohorting of patients according to presence or absence of specific pathogens coupled with conventional hygienic precautions can, however, lead to a decrease in incidence and prevalence of chronic infections with these two species, wherefore patient cohorting is now an integral component of infection control in patients with CF.
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Bronchiolar pathologic lesions result from the interplay between inflammatory and mesenchymal cells following injury to bronchioles. Offending agents include viruses, bacteria, fungi, cigarette smoke, toxic inhalants, inorganic dusts, allergens, and systemic or localized autoimmune or inflammatory processes. Bronchiolar pathologic lesions also arise in the context of allograft transplantation and pathology of the large airways and in the setting of an idiopathic disorder. ⋯ After a survey of the normal histology of bronchioles, we present a pragmatic classification that reflects the spectrum of bronchiolar pathology, illustrating the intimate interdependence of clinical, radiological, and pathologic findings in assessing the significance of bronchiolar lesions. This classification is intended to be applicable to surgical pathology material that can be correlated with clinical disease syndromes. It includes asthma-associated bronchiolar changes, chronic bronchitis/emphysema-associated bronchiolar changes, cellular bronchiolitis, respiratory bronchiolitis, bronchiolitis obliterans with intraluminal polyps/ BOOP, constrictive bronchiolitis, mineral dust small airway disease, peribronchiolar fibrosis and bronchiolar metaplasia, and bronchiolocentric nodules.
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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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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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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.