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Respiratory bronchiolitis, a common finding in cigarette smokers (smoker’s bronchiolitis), may on rare occasions present as interstitial lung disease (RB-ILD).

Respiratory bronchiolitis associated with interstitial lung disease (RB-ILD), first was described by Niewoehner et al in an autopsy study of cigarette smokers who died from non pulmonary causes in 1974.

The clinical presentation resembles those of patients with other interstitial lung diseases - cough and dyspnea, with coarse rales on physical examination.

Diffuse fine reticulonodular interstitial opacities are found on chest radiograph, usually with normal-appearing lung volumes.

Bronchial wall thickening, prominence of peribronchovascular interstitium, small regular and irregular opacities, and small peripheral ring shadows are distinctive features.

Pulmonary function testing may be normal but usually demonstrates mild to moderate restriction and normal or slightly reduced diffusing capacity. A mixed obstructive-restrictive pattern is common.

Histologically it is characterized by patchy and non-uniform accumulation of finely pigmented tan brown macrophages within membranous, terminal and respiratory bronchioles and also within immediately adjacent alveoli, and sometimes in the interstitial tissues, associated with mild interstitial fibrosis, which is limited to the peribronchiolar tissues.

Respiratory bronchiolitis-associated interstitial lung disease.Clin Chest Med. 1993 Dec;14(4):693-8.

Respiratory bronchiolitis-associated interstitial lung disease is a distinct clinical syndrome found in current or former cigarette smokers. The disease often is confused with other interstitial lung diseases, especially idiopathic pulmonary fibrosis. The clinical presentation resembles those of patients with other interstitial lung diseases--cough and dyspnea, with coarse rales on physical examination. Diffuse fine reticulonodular interstitial opacities are found on chest radiograph, usually with normal-appearing lung volumes. Bronchial wall thickening, prominence of peribronchovascular interstitium, small regular and irregular opacities, and small peripheral ring shadows are distinctive features. Pulmonary function testing may be normal but usually demonstrates mild to moderate restriction and normal or slightly reduced diffusing capacity. A mixed obstructive-restrictive pattern is common. Respiratory bronchiolitis-associated interstitial lung disease is characterized histologically by an inflammatory process involving the membranous and respiratory bronchioles. The pathologic findings are dominated by the finding of tan-brown pigmented macrophages within respiratory bronchioles and neighboring alveolar ducts and alveoli. The pulmonary parenchyma away from the airway usually is normal or may demonstrate mild hyperinflation. The clinical course and prognosis of respiratory bronchiolitis-associated interstitial lung disease are unknown. Most patients respond favorably to corticosteroids, with documented improvement in lung function and chest radiographs. Smoking appears to play a role in the pathogenesis, so smoking cessation is important in the resolution of this syndrome.

Respiratory bronchiolitis-associated interstitial lung disease (RB-ILD).Pneumologie. 2003 May;57(5):278-87.

Respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) designates interstitial lung changes in smokers, characterized histologically by bronchiolocentric accumulation of pigmented alveolar macrophages and fibrotic or cellular inflammatory changes of pulmonary interstitium. The definition is nearly identical to that of condensate pneumopathy, smoker's pneumopathy or smoker's lung, defined by accumulation of pigmented alveolar macrophages with bland alveoloseptal or peribronchial fibrosis and cellular inflammation of the bronchial wall. In addition to respiratory bronchiolitis, which is found in nearly all smokers, RB-ILD comprises a broad spectrum of varying degrees of the interstitial reaction to the exogenous injury of inhalation smoking with gradual transition to desquamative interstitial pneumonia (DIP). In most cases RB-ILD manifestations are subclinical and detected coincidentally. Radiographic features are reticulonodular and ground glass opacities of the lung. The high resolution computed tomography reveals centrilobular nodules, ground glass opacities, thickening of bronchial walls, and in some cases a reticular pattern. Mild emphysema is frequent. Lung function analysis reveals only minor restrictive or obstructive defects in most cases, often combined with hyperinflation. CO diffusing capacity is slightly to moderately impaired. Pronounced interstitial lung diseases with serious restrictive defects and arterial hypoxemia have been reported infrequently. In differential diagnosis smoking related interstitial lung diseases (DIP, Langerhans cell histiocytosis, idiopathic pulmonary fibrosis) and other interstitial lung diseases have to be excluded. In most cases diagnosis can be achieved by bronchoalveolar lavage and transbronchial lung biopsy. In cases of pronounced interstitial lung disease or assumption of an additional interstitial lung disease besides RB-ILD a thoracoscopic or open lung biopsy can be necessary. RB-ILD has a favourable prognosis. After smoking cessation lung changes are reversible. Corticosteroid therapy is not necessary. A fatal outcome of RB-ILD has not been reported. Follow-up examinations are advisable in order to preclude other interstitial lung diseases. RB-ILD seems to be more frequent than it is assumed at present. The clinical picture is masked in most cases by the concomitant smoking induced chronic bronchitis. Thus only pronounced cases with structural changes and resulting differential diagnostic problems are diagnosed.

Unlike typical cases of DIP, the disease process is centri-lobular in distribution, sparing the periphery of the secondary lobules.

Iron stain shows very fine cytoplasmic positivity within the pigmented macrophages, unlike the coarse positivity of hemosiderin granules.

The differential diagnosis of RB-ILD includes small airways disease that may occur in asbestosis , Langerhans cell histiocytosis (LCH), and DIP. Unlike asbestosis, no asbestos bodies are seen and the macrophages are finely pigmented in RB-ILD. In LCH the stellate bronchiolocentric fibrosis and the presence of S-100 positive cells are diagnostic.

UIP can be ruled out by the lack of the characteristic temporal and spatial heterogeneity.

The distinction from DIP may be difficult because of overlapping histological changes in some cases.

However, such distinction may be of little clinical significance as both diseases more or less share similar presentations and courses.

In differential diagnosis smoking related interstitial lung diseases (desquamative interstitial pneumonia , Langerhans cell histiocytosis , idiopathic pulmonary fibrosis) and other interstitial lung diseases have to be excluded). It has been suggested that RD-ILD and DIP may represent different stages of the same disease.

Long-term prognosis is good with cessation of smoking, in combination or not with corticosteroid therapy.

Idiopathic Pulmonary Fibrosis ; Acute interstitial pneumonia (AIP)/organizing diffuse alveolar damage DAD) ; Desquamative interstitial pneumonia (DIP) ; Usual Interstitial Pneumonia (UIP) ; Non-specific interstitial pneumonia (NSIP) ; Lymphocytic Interstitial Pneumonia / Follicular Bronchiolitis.

Respiratory bronchiolitis associated with interstitial lung disease.Monaldi Arch Chest Dis. 2004 Jul-Sep;61(3):174-6.

Respiratory bronchiolitis associated with interstitial lung disease (RB-ILD), first described by Niewoehner et al in an autopsy study of cigarette smokers who died from non pulmonary causes in 1974, is a rare entity that should be distinguished from the other interstitial lung diseases and in particular from desquamative interstitial pneumonia, although the two conditions share a similar histopathological pattern. RB-ILD is clearly connected with tobacco smoking and has been inserted in the "smoking related interstitial lung diseases" together with DIP and Cell histiocytosis of Langerhans; it may also be associated with occupational exposure to machine fumes. The following is a case report of a patient with both smoking and occupational exposure.

Respiratory bronchiolitis associated with interstitial lung disease and desquamative interstitial pneumonia.Clin Chest Med. 2004 Dec;25(4):717-26, vi.

This article explores issues of the diagnosis and management of respiratory bronchiolitis, respiratory bronchiolitis-associated interstitial lung disease, and desquamative interstitial pneumonia. These three diseases have common and overlapping features and sometimes are viewed as a continuum of smoking-induced disease, rather than as distinct and separate entities.

Respiratory bronchiolitis associated interstitial lung disease (RB-ILD): a case of an acute presentation.Thorax. 2004 Oct;59(10):910-1.

Respiratory bronchiolitis associated interstitial lung disease (RB-ILD) is a recently described clinicopathological entity that occurs almost exclusively in current heavy cigarette smokers. Few cases have been reported in the literature and no studies have been carried out on the effect of treatment, which currently consists of smoking cessation with or without corticosteroids. We report the first case of an acute presentation of histologically proven RB-ILD in a young cigarette smoker whose diagnosis and management proved to be difficult. Smoking cessation alone was found to be inadequate so management was combined with corticosteroid therapy.

Respiratory bronchiolitis-associated interstitial lung disease: radiologic features with clinical and pathologic correlation.J Comput Assist Tomogr. 2002 Jan-Feb;26(1):13-20.

PURPOSE: The purpose of this work was to describe the radiographic and CT findings in patients with respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) and to correlate them with clinical, physiologic, and pathologic features. METHOD: RB-ILD was proved pathologically in all 21 patients. Sixteen (76%) patients were current smokers, and five (24%) patients were ex-smokers. The mean cigarette consumption was 38.7 pack-years. Chest radiographs and CT scans were semiquantitatively analyzed and correlated with clinical findings, physiologic measures, and a pathologic score of disease extent. RESULTS: The major radiographic findings were bronchial wall thickening in 16 patients (76%) and ground-glass opacity in 12 patients (57%). The predominant initial CT findings were central bronchial wall thickening (proximal to subsegmental bronchi) in 19 patients (90%), peripheral bronchial wall thickening (distal to subsegmental bronchi) in 18 patients (86%), centrilobular nodules in 15 patients (71%), and ground-glass opacity in 14 patients (67%), None of these CT findings had a significant zonal predominance. Other findings were upper lung predominant centrilobular emphysema (57%) and patchy areas of hypoattenuation (38%) with a lower lung predominance. Radiologic findings were similar in both current and ex-smokers. The amount of ground-glass opacity correlated inversely with arterial oxygen saturation ( r = -0.67, p = 0.04), and the areas of hypoattenuation correlated with alveolar-arterial oxygen gradient ( r = 0.56, p = 0.04). The extent of centrilobular nodules correlated with the extent of macrophages in respiratory bronchioles ( r = 0.53, p = 0.03) and with chronic inflammation of respiratory bronchioles ( r = 0.57, p = 0.02). The extent of ground-glass opacity correlated with the amount of macrophage accumulation in the alveoli and alveolar ducts ( r = 0.56, p < 0.01 and r = 0.54, p = 0.04, respectively). At follow-up CT after steroid treatment and smoking cessation, in nine patients, the extent of bronchial wall thickening, centrilobular nodules, and ground-glass opacity had decreased, but the areas of hypoattenuation had increased (p < 0.05). CONCLUSION: The CT findings of RB-ILD are centrilobular nodules, ground-glass opacity, and air trapping. These radiologic features, in patients with a history of heavy cigarette smoking, may differentiate RB-ILD from other interstitial lung diseases.

Respiratory bronchiolitis with diffuse interstitial lung disease.Rev Mal Respir. 2001 Apr;18(2):201-4.

Respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) is a disease that exclusively affects cigarette smokers. Long-term prognosis is good with cessation of smoking, in combination or not with corticosteroid therapy. We report here the case of a 50-year-old patient with RB-IL diagnosed on lung biopsy. Despite corticosteroid and cyclophosphamide therapy, no functional or radiological improvement was obtained. In contrast, cessation of smoking was associated with the disappearance of the infiltrative opacities. Clinical and radiological parameters remained stable during follow-up (13 years) while a moderate obstructive pattern appeared.

Respiratory bronchiolitis associated interstitial lung disease (RB-ILD) presenting with haemoptysis.Respirology. 2000 Dec;5(4):385-7.

Respiratory bronchiolitis associated interstitial lung disease is an uncommon condition in current or ex-smokers. The presentation is non-specific, but haemoptysis is uncommonly reported in this condition. We report the case of a 25-year-old woman who presented with significant haemoptysis, dyspnoea, reduced transfer factor and normal clinical examination. In addition, a Medline literature search was performed to review the clinical features and prognosis of this disease. Other causes of haemoptysis were excluded with extensive investigation. The diagnosis was made on thoracoscopic lung biopsy. The patient had significant postoperative complications of prolonged air leak and hydropneumothorax requiring further surgery and prolonged hospital stay. Advice regarding smoking cessation was given. Her pulmonary physiology remains abnormal on follow up but symptoms have improved. Respiratory bronchiolitis-ILD may present with normal examination and radiology. Haemoptysis in this case may have been associated with the underlying disease but could have been incidental. Diagnosis, in general, requires lung biopsy. As in this patient, lung function does not appear to improve significantly on follow up.

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