Respiratory Bronchiolitis with Fibrosis. High-Resolution Computed Tomography Findings and Correlation with Pathology

Abstract

These data suggest that a CT pattern of patchy areas of reticular changes about predominantly upper zone emphysematous spaces may be seen in smokers who do not have clinical evidence of a diffuse ILD. We propose that this lesion be called respiratory bronchiolitis with fibrosis (RBF) to avoid confusion with other forms of ILD. RBF probably accounts for some of the cases of ILD seen in large radiologic surveys of smokers. The pathology literature indicates that RBF either has no functional effects or at worst represents mild, usually nonprogressive disease, and hence separation from other, more serious, forms of ILD is important. Recognition of this lesion on imaging may obviate the need for lung biopsy.

Respiratory Bronchiolitis With Fibrosis–Interstitial Lung Disease: A New Form of Smoking-Induced Interstitial Lung Disease

“…3 Katzenstein et al 3 identified RBF as well as RB in 45% of extensively sampled resected lungs from cigarette smokers and termed the lesions ''smoking-related interstitial fibrosis.'' Yousem 1 found the same lesion in 4 of 30 lungs resected for lung cancer where there was no clinical question of ILD, and 2 of the cases in our series 4 were also incidental findings in lung cancer resection specimens. Kawabata et al 2 described pathologic changes, termed airspace enlargement with fibrosis, some of which are the same thing (although they also appear to be including examples of centrilobular emphysema with fibrosis in the emphysematous space, which is not the same thing), in lungs from smokers; the incidence of the lesion increased with amount of smoking and was present in 21% of the heaviest smokers.…”

“…In his more recent description Yousem 1 suggested that some RBF patients may have signs and symptoms of an ILD, and 2 of his patients had a mixed obstructive/restrictive abnormality (ie, RBFILD). In our series, 4 3 patients had mild airflow obstruction, whereas 2 had airflow obstruction with evidence of restriction; however, both of these latter patients were massively obese (body mass indexes of 46 and 38, respectively), so the evidence for ILD-associated functional abnormalities is equivocal. Given the frequency of RBF morphology in cigarette smokers, other series of RBILD patients probably include patients with RBF as well.…”

“…Thus, to avoid confusion we think it useful to assign the lesion a different name and have proposed RBF. 4 Why separate RBF from RB? The most important reasons are (1) as opposed to RB/RBILD, RBF is frequently mistaken, either on biopsy or HRCT, for a diffuse fibrosing interstitial pneumonia; indeed, Yousem's original point was that this in fact was not a diffuse fibrosing lung disease; (2) RBF has a distinctive radiologic appearance on HRCT and consists of sharply circumscribed upper zonal and midzonal subpleural foci of emphysema mixed with reticulation ( Figure 1, C), sometimes accompanied by areas of ground glass opacity (Figure 1, C).…”

“…3 We have suggested that, to avoid confusion with other forms of smoking-related interstitial lung disease (ILD), the lesion be referred to as respiratory bronchiolitis with fibrosis (RBF). 4 Most importantly, we have found that this pathologic abnormality often has a distinctive high-resolution computed tomography (HRCT) correlate, such that in many cases RBF should be diagnosable on the basis of imaging. 4 The purpose of this short article is to suggest how RBF fits into the general category of smoking-related ILD, and particularly to compare it with two possibly related forms of accepted smoking-related ILDs: respiratory bronchiolitisinterstitial lung disease (RBILD) and desquamative interstitial pneumonia (DIP).…”

CT-Definable Subtypes of Chronic Obstructive Pulmonary Disease: A Statement of the Fleischner Society

“…Similar changes were also seen in 2563 cigarette smokers in the MESA Lung Study and in the National Lung Screening Trial (112,113). Although detailed pathologic correlation is not available, these interstitial abnormalities likely correspond to variable combinations of respiratory bronchiolitis, airspace enlargement with fibrosis, and smoking-related interstitial fibrosis (114)(115)(116).…”