Clinical significance of respiratory bronchiolitis on open lung biopsy and its relationship to smoking related interstitial lung disease

Abstract

Background-Respiratory bronchiolitisassociated interstitial lung disease (RBILD) is a rare form of interstitial lung disease which may present in similar fashion to other types of chronic interstitial pneumonia. The purpose of this study was to undertake a clinicopathological review of 10 patients with RBILD and to examine the clinical and imaging data related to its histopathological pattern, in particular the relationship of RBILD to smoking. Methods-Thirteen out of 168 retrospectively reviewed patients, from whom biopsy specimens were taken for suspected diVuse lung disease, were identified with a histopathological pattern of RBILD. Three cases were rejected as follow up data were unavailable. The 10 remaining cases constituted the study group and both clinical and imaging data were collected from patients' notes and referring physicians. Results-Histopathologically, four cases of RBILD overlapped with the pattern of desquamative interstitial pneumonitis (DIP) and nine also had microscopic evidence of centrilobular emphysema. Nine patients were smokers, ranging from 3 to 80 pack years. The one non-smoker had an occupational exposure to the fumes of solder flux. The sex distribution was equal with an age range of 32-65 years. Two patients were clubbed. Lung function tests showed both restrictive and obstructive patterns together with severe reductions in carbon monoxide transfer factor in seven patients. Chest radiographs showed reticular or reticulonodular infiltrates in five patients and a ground glass pattern in two. CT scans were consistent with either DIP or RBILD in six of eight patients. Although seven patients remained stable or improved, either with or without treatment, three patients deteriorated. Conclusions-This study adds weight to the hypothesis that smoking can cause clinically significant interstitial lung disease, with deterioration in pulmonary function despite treatment. Given the overlapping histopathological patterns of RBILD and DIP and their strong association with smoking, the term "smoking related interstitial lung disease" is suggested for those patients who are smokers.

Respiratory Bronchiolitis/Interstitial Lung Disease

“…The onset of RB-ILD is usually insidious with exertional dyspnea, symptomatic wheezing, and persistent cough, which may be non-productive, developing over a course of weeks or months [6][7][8]13]. This clinical picture can be masked by concomitant smoking-related chronic bronchitis.…”

“…In spite of the substantial clinical heterogeneity of these studies, it has been consistently reported that patients with RB-ILD are usually ever cigarette smokers with at least 30 pack-years at the time of diagnosis [6][7][8][9]12,13]. Only incidental single cases of RB-ILD in non-smokers have been reported, including patients exposed to second-hand smoke [8,16].…”

“…Only incidental single cases of RB-ILD in non-smokers have been reported, including patients exposed to second-hand smoke [8,16]. The age at symptom onset ranges from 22 to 70 years, with median values of 36-54 years [6][7][8]12,13].…”

“…Contrary to RB alone, RB-ILD is an uncommon disorder found in a far smaller proportion of smokers [4,6]. Some authors have regarded RB-ILD as an exaggerated RB with more extensive peribronchiolar interstitial fibrosis [7][8][9], while others [4,6] have considered the histologic features of RB and RB-ILD indistinguishable and have separated the two based on the presence of clinical evidence of ILD.…”

“…Most insight into RB-ILD to date has been provided by five case series [6][7][8]12,13] totaling 78 patients with biopsy-proven RB-ILD, These studies have provided descriptions of clinical and physiological features, pathological and radiographic/HRCT appearances, and outcomes of the disease. Additionally, there have been several other reports focused mainly on the differential diagnosis of RB-ILD based on radiological findings [9] and their correlation with clinical and physiological findings [14], or on follow-up after smoking cessation [14,15].…”