Respiratory bronchiolitis associated with interstitial lung disease and desquamative interstitial pneumonia
Section snippets
Respiratory bronchiolitis
RB is a common incidental finding on histopathologic examination of lung samples that are obtained from heavy smokers. Pigmented macrophages accumulate within respiratory bronchioles and adjacent alveoli [2], with a characteristic histopathologic picture of peribronchiolar inflammation and fibrosis that was first described in 1974 [3]. These features, usually found in asymptomatic individuals, often are incidental findings on lung biopsy or at postmortem. Whether this entity should be viewed as
Histopathology
The histopathology of RBILD and RB are identical. The main feature is the accumulation of alveolar macrophages within respiratory bronchioles, with the infiltrate extending into neighboring alveoli. Macrophages are characterized by glassy eosinophilic cytoplasm with light brown and finely granular pigmentation that often is superimposed and is believed to represent constituents of cigarette smoke. Foamy macrophages are not a feature of these disorders.
Generally, a chronic inflammatory cell
Smoking relationship
RB has been associated almost invariably with smoking. The largest histopathologic study reported the clinical and pathologic features of 109 cases of RB that were identified from review of 156 consecutive surgical lung biopsy specimens [11]. Of the lung biopsy specimens, 107 had RB, including all 83 current smokers and 24 of 49 ex-smokers (49%). RB persisted for many years after stopping smoking; it occurred 5 years after quitting in one third of patients and 32 years later in one patient.
Pulmonary function testing
The functional impairment in RBILD varies between clinical series [4], [6], [9]. The common picture is a mixed, predominately restrictive pattern with a moderate reduction in DLCO, despite the bronchiolocentric nature of disease.
Although the level of functional impairment is a defining diagnostic feature that distinguishes RBILD from RB, it remains unclear why some patients who have moderately extensive fibrotic change that radiates from bronchioles have little or no abnormality of their
Clinical features at presentation, prognosis, and treated course
In RBILD and DIP, the most frequent presenting features are the insidious onset of exertional breathlessness and a persistent cough that is not always productive of sputum [6], [9], [10], [14]. Chest pain and systemic symptoms, including weight loss and fatigue, also can be present. Bibasilar end-inspiratory crackles are present frequently but clubbing is rare. The diagnoses of RBILD and DIP are made on the basis of the pattern of disease and demonstration of imaging and functional abnormality;
Difficult clinical issues
We are left with some uncertainties. HRCT will allow DIP (ground-glass attenuation being more intense and regional) [8], [46] and more progressive forms of idiopathic interstitial pneumonia (UIP, fibrotic NSIP) to be distinguished from RBILD. There may, however, be difficulties in separating RBILD from subacute hypersensitivity pneumonitis; widespread poorly formed micronodular abnormalities and regional hypoattenuation can occur in both diseases [26], [33]. In such a case, the smoking history
Are desquamative interstitial pneumonia and respiratory bronchiolitis–associated interstitial lung disease the same disease?
The overlap in histopathologic and HRCT features in some patients led to the postulate that a morphologic continuum exists from asymptomatic RB, through RBILD, to DIP [7], [8]. Despite the attraction of a simplification of terminology, however, recent consensus statements tended to classify RBILD and DIP as separate entities, although they have many common features, including smoking, HRCT, and histopathology [47], [48]. Reasons for continued separate classification include:
Exact severity
A suggested schema
RB should be considered as a normal consequence of cigarette smoking that is present to some degree in all smokers and often is associated with cough. If present, HRCT and pulmonary function abnormalities are necessarily mild (more severe abnormalities equate to RBILD).
RB-interstitial lung disease can be viewed as unusually severe RB and requires for diagnosis:
Moderately extensive typical HRCT abnormalities AND
Reduced lung volumes and gas transfer, in the absence of, or out of keeping with HRCT
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Cited by (36)
Smoking-Related—Interstitial Lung Disease
2021, Encyclopedia of Respiratory Medicine, Second EditionDesquamative interstitial pneumonia with clinical, radiological and histologic correlation
2019, Radiology Case ReportsCitation Excerpt :As DIP and RB-ILD reactions are often frequent and incidental findings in the lung tissue of smokers, formal clinical diagnosis of these conditions is dependent upon the presence of significant symptoms, radiographic changes, and functional impairment. When taken into account together, DIP and RB-ILD account for up to 15%-20% of patients with idiopathic interstitial pneumoniae biopsies [2–5]. Patients diagnosed with RB-ILD and DIP are typically male, in their 40s or 50s, with an average of a 30 pack-year smoking history.
Evaluation of clinical presentation and outcome of patients with respiratory bronchiolitis-associated interstitial lung disease
2015, Revista Portuguesa de PneumologiaDiffuse smoking-related lung disease: Emphysema and interstitial lung disease
2015, Seminars in RoentgenologyCitation Excerpt :Most patients present as young adults in their 30s-40s with symptoms of mild dyspnea and cough.53 PFTs typically demonstrate a decreased DLCO with a mixed obstructive-restrictive pattern.52,53,55 Chest radiograph findings are often normal but can include fine bilateral upper lobe–predominant reticulonodular opacities.31
Respiratory bronchiolitis and lung carcinoma
2013, Respiratory InvestigationCitation Excerpt :In summary, although many cases of RB, including RB-ILD, are overlooked because of their mild clinical symptoms and good prognoses, RB with fibrosis may be a risk factor for the development of lung cancer, especially peripheral-type squamous cell carcinoma. It has been reported that both RB and RB-ILD are expected to improve after smoking cessation [31]; similarly, in our study, pathological RB features were found in only current smokers. IPF and UIP have already been recognized as high risk factors for the development of lung carcinoma.
Prognostic value of clinical, morphologic, and immunohistochemical factors in patients with bronchiolitis obliterans-organizing pneumonia
2013, Human PathologyCitation Excerpt :In addition, before making a diagnosis of BOOP, we have to exclude any infection with special stains or cultures. BOOP and desquamative interstitial pneumonia are closely associated with histologic patterns of interstitial pneumonia [22,23]. The distinctive feature in BOOP is bronchocentricity, whereas desquamative interstitial pneumonia is diffuse within pulmonary acini [24,25].