Changes in HRCT findings in patients with respiratory bronchiolitis-associated interstitial lung disease after smoking cessation

Why making smoking cessation a priority for rare interstitial lung disease smokers?

This review aims to discuss the complex relationship between smoking and interstitial lung diseases (ILDs), emphasizing the significant morbidity and mortality associated with these conditions. While the etiology of ILDs remains multifactorial, cigarette smoking emerges as a prominent modifiable risk factor implicated in their pathogenesis and progression. This narrative review will provide insight into smoking-associated interstitial lung diseases and personalised approaches to smoking cessation. Epidemiological studies consistently link smoking to ILDs such as idiopathic pulmonary fibrosis (IPF), respiratory bronchiolitis-associated ILD (RB-ILD), and desquamative interstitial pneumonia (DIP), highlighting the urgent need for comprehensive tobacco cessation strategies. Despite the established benefits of smoking cessation, adherence to cessation programs remains challenging due to nicotine addiction, psychological factors, and social influences. The modest success rates of smoking cessation in ILD patients, emphasises the importance of tailored interventions and ongoing support is needed to overcome barriers and to improve outcomes of quitting smoking in this category of vulnerable patients.

Air trapping in small airway diseases: A review of imaging technique and findings with an overview of small airway diseases

Air trapping is a common finding radiologists encounter on CT imaging of the thorax. This term is used when there are geographic areas of differing attenuation within the lung parenchyma. Most commonly, this is the result of abnormal retention of air due to complete or partial airway obstruction from small airway pathologies. Perfusional differences due to underlying vascular diseases could also result in these appearances, and hence, inspiratory and full expiratory phase CT studies are required to accurately diagnose air trapping. It is important to note that this can occasionally be present in healthy patients. Multiple diseases are associated with air trapping. Determining the aetiology relies on accurate patient history and concomitant findings on CT. There is currently no consensus on accurate assessment of the severity of air trapping. The ratio of mean lung density between expiration and inspiration on CT and the change in lung volume have demonstrated a positive correlation with the presence of small airway disease. Treatment and resultant patient outcome depend on the underlying aetiology, and hence, radiologists need to be familiar with the common causes of air trapping. This paper outlines the most common disease processes leading to air trapping, including Constrictive bronchiolitis, Hypersensitivity pneumonitis, DIPNECH, and Post-infectious (Swyer-James/Macleod). Various diseases result in the air trapping pattern seen on the expiratory phase CT scan of the thorax. Combining patient history with other concomitant imaging findings is essential for accurate diagnosis and to further guide management.

Smoking-Related Interstitial Lung Diseases

Smoking-related interstitial lung diseases (ILDs) are a group of heterogeneous, diffuse pulmonary parenchymal disease processes associated with tobacco exposure. These disorders include pulmonary Langerhans cell histiocytosis, respiratory bronchiolitis-associated ILD, desquamative interstitial pneumonia, acute eosinophilic pneumonia, and combined pulmonary fibrosis and emphysema. This review summarizes the current evidence of pathogenesis, clinical manifestations, diagnostic approach, prognosis, and treatment modalities for these diseases. We also discuss the interstitial lung abnormalities incidentally detected in radiologic studies and smoking-related fibrosis identified on lung biopsies.

ACR Appropriateness Criteria® Diffuse Lung Disease

Diffuse lung disease, frequently referred to as interstitial lung disease, encompasses numerous disorders affecting the lung parenchyma. The potential etiologies of diffuse lung disease are broad with several hundred established clinical syndromes and pathologies currently identified. Imaging plays a critical role in diagnosis and follow-up of many of these diseases, although multidisciplinary discussion is the current standard for diagnosis of several DLDs. This document aims to establish guidelines for evaluation of diffuse lung diseases for 1) initial imaging of suspected diffuse lung disease, 2) initial imaging of suspected acute exacerbation or acute deterioration in cases of confirmed diffuse lung disease, and 3) clinically indicated routine follow-up of confirmed diffuse lung disease without acute deterioration. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Immunopathogenesis and therapeutic potential of macrophage influx in diffuse parenchymal lung diseases

INTRODUCTION

The diffuse parenchymal lung diseases (DPLD)/interstitial lung diseases (ILD) are progressive lung disorders with usually unclear etiology, poor long-term survival and no effective treatment. Their pathogenesis is characterized by alveolar epithelial cell injury, inflammation, epithelial-mesenchymal transition, and parenchymal fibrosis. Macrophages play diverse roles in their development, both in the acute phase and in tissue repair.

AREAS COVERED

In this review, we summarize the current state of knowledge regarding the role of macrophages and their phenotypes in the immunopathogenesis of DPLDs; CVD-ILD, UIP, NSIP, DIP, RB-ILD, AIP, HP, Sarcoidosis, etc. Our goal is to update the understanding of the immune mechanisms underlying the initiation and progression of fibrosis in DPLDs. This will help in identification of biomarkers and in developing novel therapeutic strategies for DPLDs. A thorough literature search of the published studies in PubMed (from 1975 to 2020) was done.

EXPERT OPINION

The macrophage associated inflammatory markers needs to be explored for their potential as biomarkers of disease activity and progression. Pharmacological targeting of macrophage activation may reduce the risk of macrophage activation syndrome (MAS) and help improving the survival and prognosis of these patients.

Smoking-associated interstitial lung disease: update and review

INTRODUCTION

Smoking-associated interstitial lung disease manifests as several heterogeneous disorders involving the airways, pleura, and lung parenchyma with various radiological patterns. The clinical history, radiologic, and pathologic findings are important to distinguish these more uncommon diseases. A multidisciplinary approach is recommended for diagnosis and to manage these conditions appropriately.

AREAS COVERED

This review provides an overview of the epidemiology, risk factors, pathogenesis, clinical features, diagnosis, and treatment of acute eosinophilic pneumonia, e-cigarettes, or vaping associated lung injury, respiratory bronchiolitis interstitial lung disease, desquamative interstitial pneumonitis, pulmonary Langerhans cell histiocytosis, idiopathic pulmonary fibrosis, and combined pulmonary fibrosis emphysema.

EXPERT OPINION

Cigarette smoking is associated with a variety of pathologic conditions that affect the airways and lungs. E-cigarette use and vaping present new challenges to the clinician. Consensus between the clinical, radiographic, and pathologic findings is important in identifying and differentiating between the various entities to properly diagnose smoking-related interstitial lung diseases discussed in this review.

Questions and Answers on Smoking in Patients With Diffuse ILD. Use of PICO Methodology

INTRODUCTION

The Smoking and the Diffuse Interstitial Lung Diseases (ILD) groups of ALAT and SEPAR collaborated in the preparation of this document.

MATERIALS AND METHODS

This document uses PICO methodology to answer various questions on the relationship between tobacco use and diffuse ILD.

RESULTS AND CONCLUSIONS

The main recommendations are: a) moderate level of evidence and strong recommendation to consider smoking as a risk factor for the development and/or modification of the progression of diffuse ILD; b) moderate level of evidence to identify an increase in mortality in diffuse ILD, irrespective of histologic pattern. Low evidence for ascribing it to smoking and strong recommendation for the early identification of patients with diffuse ILD. Further studies are needed to evaluate the effect of smoking cessation in patients with diffuse ILD; c) low level of evidence and weak recommendation for defining the impact of passive smoking in diffuse ILD; d) low level of evidence to demonstrate that smoking cessation improves the outcomes of patients diagnosed with diffuse ILD and strong recommendation to advise smoking cessation in smokers with diffuse ILD, and e) low level of evidence to support the clinical or epidemiological usefulness of active case finding for diffuse ILD in smoking cessation programs, and strong recommendation justifying the performance of spirometry in active case finding, based not on current smoking status, but on previous accumulated consumption, even in asymptomatic cases.

The place of high-resolution computed tomography imaging in the investigation of interstitial lung disease

INTRODUCTION

High-resolution computed tomography (HRCT) has revolutionized the diagnosis, prognosis and in some cases the prediction of therapeutic response in interstitial lung disease (ILD). HRCT represents an essential second step to a patient's clinical history, before considering any other investigation, including lung biopsy. Areas covered: This review describes the current place of HRCT in the diagnosis, prognosis and monitoring of ILD. It also lists some perspectives for the near future. Expert commentary: Since the 1980s, HRCT and its interpretation have improved, the diagnosis value of patterns, and the integration of bio-clinical elements to HRCT have been better standardized. The interobserver agreement has been investigated, allowing a better use of some limits in the interpretation of various signs. It not only takes into account one particular predominant sign, but the combination of patterns and the distribution of findings. Thanks to HRCT, the range of diagnoses and their probability are more accurately identified. The contribution of HRCT has been optimized during the multidisciplinary discussion that a difficult diagnosis calls for. HRCT quantification of the extent of diffuse lung disease becomes possible and is linked to prognosis. In the future, artificial intelligence may significantly modify the practice of radiology.

Smoking-Related Lung Disease

Smoke from cigarettes and other sources may induce a variety of patterns of lung injury. While smoking related lung diseases, in general, have a better prognosis than many other diffuse lung diseases, they may be a cause of significant symptoms and, in some cases, may even require lung transplantation. On histology, the manifestations of these patterns range from reversible inflammation to irreversible emphysema or fibrosis. High-resolution chest CT plays a critical role in the diagnosis of smoking related lung diseases. It has several roles including (1) helping determine diagnosis, (2) assessing the pattern of injury that is present, (3) evaluating the extent and severity of disease, and (4) determining the response to treatment. The practicing radiologist must have a knowledge of the clinical, pathologic, and imaging features of the differnent patterns of lung injury associated with smoke inhalation.

Overlaps and uncertainties of smoking-related idiopathic interstitial pneumonias

Smoking-related interstitial lung disease (ILD) consists of a heterogeneous group of disorders that are considered a distinct entity. The 2013 American Thoracic Society and European Respiratory Society recommendations classified respiratory bronchiolitis (RB)/RB-ILD and desquamative interstitial pneumonia (DIP) as smoking-related idiopathic interstitial pneumonias (IIPs). The overlapping histopathological and radiological patterns of smoking-related IIPs must be considered. Overlap patterns of smoking-related IIPs are not easily classified as a single disorder. The initial radiological manifestation and follow-up changes are heterogeneous, even when diagnosed pathologically as RB or DIP. Therefore, a clinical–radiological–pathological consensus is important in the diagnosis of smoking-related IIPs, and long-term evaluation is essential to monitor the morphological changes in these patients. In this article, we reviewed the clinical, radiological, and pathological findings, and also the changes in radiological manifestations of smoking-related IIPs over time.

The role of high-resolution computed tomography in the follow-up of diffuse lung disease

High-resolution computed tomography (HRCT) of the lung is a key component of the multidisciplinary approach to diagnosis in diffuse lung disease (DLD). HRCT also plays an important role in the follow-up of patients with established DLD. In this respect, serial HRCT examinations may provide valuable information that cannot be determined from clinical history and other diagnostic tests, such as pulmonary function tests. Important roles of HRCT in this context include assisting in determining prognosis, monitoring for the efficacy of treatment, detecting progression of disease or complications, and evaluating patients with worsening or acute symptoms. Both clinicians and radiologists should be aware of the expected evolution of HRCT changes in a variety of DLDs. The goals of this paper are to discuss: 1) the expected evolution of HRCT findings over time in common DLDs; 2) the role of serial HRCT examinations in formulating an initial diagnosis; and 3) the role of HRCT in the follow-up of patients with known DLD.

HRCT plays an important role in the follow-up of patients with diffuse lung diseasehttp://ow.ly/wzY730c2gRO

Are interstitial lung abnormalities associated with COPD? A nested case-control study

Purpose

In this study, we tested the association between COPD and interstitial lung abnormality (ILA), notably in relation to the presence of computed tomography (CT) signs of lung fibrosis.

Patients and methods

COPD cases were selected from participants undergoing lung cancer screening (Multicentric Italian Lung Detection trial) for airflow obstruction (n=311/2,303, 13.5%) and 146 consecutive patients with clinical COPD. In all, 457 COPD cases were selected and classified according to the stages of Global Initiative for Chronic Obstructive Lung Disease. A nested matching (case:control = 1:2) according to age, sex, and smoking history was operated between each COPD case and two control subjects from Multicentric Italian Lung Detection trial without airflow obstruction. Low-dose CT scans of COPD cases and controls were reviewed for the presence of ILA, which were classified into definite or indeterminate according to the presence of signs of lung fibrosis.

Results

The frequency of definite ILA was similar between COPD cases and controls (P=0.2), independent of the presence of signs of lung fibrosis (P=0.07). Combined definite and indeterminate ILA was homogeneously distributed across Global Initiative for Chronic Obstructive Lung Disease stages (P=0.6). Definite ILA was directly associated with current smoker status (odds ratio [OR] 4.05, 95% confidence interval [CI]: 2.2–7.4) and increasing pack-years (OR 1.01, 95% CI: 1–1.02). Subjects with any fibrotic ILA were more likely to be older (OR 1.17, 95% CI: 1.10–1.25) and male (OR 8.58, 95% CI: 1.58–68.9).

Conclusion

There was no association between COPD and definite ILA. However, low-dose CT signs of lung fibrosis were also observed in COPD, and their clinical relevance is yet to be determined.

American Thoracic Society-European Respiratory Society Classification of the Idiopathic Interstitial Pneumonias: Advances in Knowledge since 2002

In the updated American Thoracic Society-European Respiratory Society classification of the idiopathic interstitial pneumonias (IIPs), the major entities have been preserved and grouped into (a) "chronic fibrosing IIPs" (idiopathic pulmonary fibrosis and idiopathic nonspecific interstitial pneumonia), (b) "smoking-related IIPs" (respiratory bronchiolitis-associated interstitial lung disease and desquamative interstitial pneumonia), (c) "acute or subacute IIPs" (cryptogenic organizing pneumonia and acute interstitial pneumonia), and (d) "rare IIPs" (lymphoid interstitial pneumonia and idiopathic pleuroparenchymal fibroelastosis). Furthermore, it has been acknowledged that a final diagnosis is not always achievable, and the category "unclassifiable IIP" has been proposed. The diagnostic interpretation of the IIPs is often challenging because other diseases with a known etiology (most notably, connective tissue disease and hypersensitivity pneumonitis) may show similar morphologic patterns. Indeed, more emphasis has been given to the integration of clinical, computed tomographic (CT), and pathologic findings for multidisciplinary diagnosis. Typical CT-based morphologic patterns are associated with the IIPs, and radiologists play an important role in diagnosis and characterization. Optimal CT quality and a systematic approach are both pivotal for evaluation of IIP. Interobserver variation for the various patterns encountered in the IIPs is an issue. It is important for radiologists to understand the longitudinal behavior of IIPs at serial CT examinations, especially for providing a framework for cases that are unclassifiable or in which a histologic diagnosis cannot be obtained.

Respiratory bronchiolitis-interstitial lung disease

Respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) is a rare, mild inflammatory pulmonary disorder that occurs almost exclusively in current or former heavy smokers, usually between the third and sixth decades, most likely with no gender predilection. The onset is usually insidious with exertional dyspnea and persistent cough, which may be non-productive, developing over a course of weeks or months. RB-ILD may also be diagnosed in asymptomatic patients with functional impairment and chest radiograph or high-resolution computed tomography (HRCT) abnormalities. Histologically, RB-ILD is characterized by the accumulation of yellow-brown pigmented macrophages within the lumens of respiratory bronchioles and alveolar ducts, associated with a patchy submucosal and peribronchiolar chronic inflammation. Common findings also include mild bronchiolar and peribronchiolar alveolar fibrosis that expands contiguous alveolar septa and leads to architectural distortion as well as centrilobular emphysema. Chest radiographs in patients with RB-ILD typically show fine reticulonodular interstitial opacities, while on HRCT central and peripheral bronchial wall thickening, centrilobular nodules, and ground-glass opacities associated with upper lobe centrilobular emphysema are most frequently reported. Pulmonary function testing may be normal but usually demonstrates mixed, predominantly obstructive abnormalities, often combined with hyperinflation and usually associated with a mild to moderate reduction in carbon monoxide diffusion capacity (DLco). The course of RB-ILD is heterogeneous. Some patients respond favorably to corticosteroids and/or smoking cessation, but often there is no functional improvement and the disease progresses despite smoking cessation and treatment.

Clinical and radiological features of idiopathic interstitial pneumonias (IIPs): a pictorial review

OBJECTIVES

To illustrate the clinical and radiological features of idiopathic interstitial pneumonias (IIPs), according to the American Thoracic Society (ATS)/European Respiratory Society (ERS) classification updated in 2013.

METHODS

IIPs include a subset of diffuse and restrictive lung diseases, resulting from damage to the parenchyma characterised by inflammation and fibrosis of the interstitium. Classification into major and rare IIPs is based on the 2013 ATS/ERS committee.

RESULTS

The diagnosis of idiopathic pulmonary fibrosis (IPF) needs to exclude other well-known causes of interstitial lung diseases. According to the 2011 evidence-based guidelines, usual interstitial pneumonia (UIP) can be diagnosed by HRCT when all criteria are fulfilled. Non-specific interstitial pneumonia (NSIP) is characterised by patchy ground-glass opacities and irregular linear/reticular opacities. The imaging patterns of respiratory bronchiolitis associated-interstitial lung disease (RB-ILD) and desquamative interstitial pneumonia (DIP) show centrolobular nodules and ground-glass opacities. Cryptogenic organising pneumonia (COP) consists of patchy peripheral or peribronchial consolidations, while ground-glass opacities are typically associated with diffuse lung consolidation, evolving to fibrosis, in acute interstitial pneumonia (AIP). Rare IIPs include lymphoid interstitial pneumonia and idiopathic pleuro-parenchymal fibroelastosis (IPPFE).

CONCLUSIONS

The knowledge of IIP imaging features on HRCT images help radiologists in diagnosis. Moreover, the overlap of imaging features needs a multidisciplinary approach.

TEACHING POINTS

• UIP findings are reticulations, bronchiectasis, honeycombing and absence of inconsistent features. • Bilateral patchy ground-glass areas represent the most encountered features in NSIP. • Poorly defined centrilobular nodules are typical of RB-ILD, whereas a ground-glass appearance is typical of DIP. • HRCT features of COP include characteristic peripheral or peribronchial patchy consolidations. • Rare IIPs include idiopathic LIP and idiopathic pleuro-parenchymal fibroelastosis (PPFE).

Smoking cessation in COPD causes a transient improvement in spirometry and decreases micronodules on high-resolution CT imaging

BACKGROUND

Smoking cessation is of major importance for all smokers; however, in patients with COPD, little information exists on how smoking cessation influences lung function and high-resolution CT (HRCT) scan appearances.

METHODS

In this single-center study, we performed screening spirometry in a group of heavy smokers aged 40 to 80 years (N = 358). We then studied the effects of smoking cessation in two groups of selected subjects: smokers with COPD (n = 38) and smokers with normal spirometry (n = 55). In parallel to subjects undergoing smoking cessation, we studied a control group of nonsmokers (n = 19).

RESULTS

Subjects with COPD who quit smoking had a marked, but transient improvement in FEV1 at 6 weeks (184 mL, n = 17, P < .01) that was still present at 12 weeks (81 mL, n = 17, P < .05) and only partially maintained at 1 year. In contrast, we saw improvement in the transfer factor of lung for carbon monoxide at 6 weeks in both subjects with COPD who quit smoking (0.47 mmol/min/kPa, n = 17, P < .01) and subjects who quit smoking with normal spirometry (0.40 mmol/min/kPa, n = 35, P < .01). An upper-zone single HRCT image slice reliably identified emphysema at baseline in 74% of smokers with COPD (28 of 38) and 29% of healthy smokers (16 of 55). Smoking cessation had no significant effect on the appearances of emphysema but decreased the presence of micronodules on HRCT imaging.

CONCLUSIONS

Cigarette smoking causes extensive lung function and HRCT image abnormalities, even in patients with normal spirometry. Smoking cessation has differential effects on lung function (FEV1 and gas transfer) and features on HRCT images (emphysema and micronodules). Cessation of smoking in patients with COPD causes a transient improvement in FEV1 and decreases the presence of micronodules, offering an opportunity for concomitant therapy during smoking cessation to augment these effects. Smoking cessation at the earliest possible opportunity is vital to minimize permanent damage to the lungs.

Interstitial lung abnormalities in a CT lung cancer screening population: prevalence and progression rate

PURPOSE

To determine the prevalence of interstitial lung abnormalities (ILAs) at initial computed tomography (CT) examination and the rate of progression of ILAs on 2-year follow-up CT images in a National Lung Screening Trial population studied at a single site.

MATERIALS AND METHODS

The study was approved by the institutional review board and informed consent was obtained from all participants. Image review for this study was HIPAA compliant. We reviewed the CT images of 884 cigarette smokers who underwent low-dose CT at a single site in the National Lung Screening Trial. CT findings were categorized as having no evidence of ILA, equivocal for ILA, or ILA. We categorized the type of ILA as nonfibrotic (ground-glass opacity, consolidation, mosaic attenuation), or fibrotic (ground glass with reticular pattern, reticular pattern, honeycombing). We evaluated the temporal change of the CT findings (no change, improvement, or progression) of ILA at 2-year follow-up. A χ(2) with Fisher exact test or unpaired t test was used to determine whether smoking parameters were associated with progression of ILA at 2-year follow-up CT.

RESULTS

The prevalence of ILA was 9.7% (86 of 884 participants; 95% confidence interval: 7.9%, 11.9%), with a further 11.5% (102 of 884 participants) who had findings equivocal for ILA. The pattern was fibrotic in 19 (2.1%), nonfibrotic in 52 (5.9%), and mixed fibrotic and nonfibrotic in 15 (1.7%) of the 86 participants with ILA. The percentage of current smokers (P = .001) and mean number of cigarette pack-years (P = .001) were significantly higher in those with ILA than those without. At 2-year follow-up of those with ILA (n = 79), findings of nonfibrotic ILA improved in 49% of cases and progressed in 11%. Fibrotic ILA improved in 0% and progressed in 37% of cases.

CONCLUSION

ILA is common in cigarette smokers. Nonfibrotic ILA improved in about 50% of cases, and fibrotic ILA progressed in about 37%.

Bronchiolitis in young female smokers

BACKGROUND

Smoking is a growing concern among young women. However, the pulmonary effects of smoking in young female smokers in their 20's are unknown.

OBJECTIVE

The purpose of this study was to determine whether young female smokers demonstrate smoking-related lung abnormalities such as bronchiolitis in their 20's.

METHODS

We recruited young females (20-30 yr) from Izmir, Turkey; 29 smokers and 31 lifetime non-smokers. They were all asymptomatic. All subjects performed complete lung function measurements and underwent thoracic computed tomography (CT) scanning at suspended full inspiration using a Toshiba "Aquilion" multi-slice CT scanner. The CT images were analyzed using custom software (Emphylx-J) and published equations to calculate total lung volume, mean lung density, lung mass, and the extent of emphysema. CT images were also read semi-quantitatively for respiratory bronchiolitis and emphysema by 2 experienced chest radiologists. When there was substantial difference in scoring, a 3rd (independent) radiologist read the CT scans. Plasma biomarkers of smoking were also measured in these subjects.

RESULTS

Although none of the subjects demonstrated emphysema on CT images, 41% of smokers (compared with only 15% of non-smokers) had evidence for respiratory bronchiolitis (with a score of 2 or more; p = 0.0301). There was a significant relationship between pack-years of smoking and the severity of respiratory bronchiolitis in smokers. Plasma interleukin (IL)-6 levels were also higher in smokers than in non-smokers (p = 0.028). Quantitative analysis for emphysema or airways disease on CT scans did not reveal any significant differences in the two groups with the exception of lung mass, which was higher in the smokers than in non-smokers. Lung function was similar between the two groups.

CONCLUSION AND CLINICAL RELEVANCE

Young female smokers in their 20's and 30's demonstrate CT changes consistent with respiratory bronchiolitis and elevated plasma IL-6 levels. They also have "heavier" lungs compared with lifetime non-smokers. These data indicate that pathologic changes of smoking occur early in young female smokers in the absence of demonstrable airflow limitation or symptoms. Public health efforts to curb smoking in young women are clearly needed to reduce the burden of smoking related lung disease in women.

Smoking and idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a disease of unknown etiology with considerable morbidity and mortality. Cigarette smoking is one of the most recognized risk factors for development of IPF. Furthermore, recent work suggests that smoking may have a detrimental effect on survival of patients with IPF. The mechanism by which smoking may contribute to the pathogenesis of IPF is largely unknown. However, accumulating evidence suggests that increased oxidative stress might promote disease progression in IPF patients who are current and former smokers. In this review, potential mechanisms by which cigarette smoking affects IPF, the effects of cigarette smoking on accelerated loss of lung function in patients with IPF, key genetic studies evaluating the potential candidate genes and gene-environment (smoking) interaction, diagnosis, and treatment with emphasis on recently closed and ongoing clinical trials are presented.

Benefits of smoking cessation with focus on cardiovascular and respiratory comorbidities

Smoking cessation is crucial in preventing premature morbidity, disability and mortality worldwide. The effectiveness of quitting tobacco use surpasses any other intervention to minimise the risk for chronic cardiac and respiratory conditions. The overall health benefits of smoking cessation have been recognised for decades but as tobacco legislation has been changing in recent years, new evidence particularly concerning the effect of less smoke exposure on the vascular system has emerged. Recently, much research in chronic obstructive pulmonary disease (COPD) has concerned the ongoing inflammation - also in former smokers - and disease heterogeneity, which provides new knowledge regarding current and ex-smokers with COPD. Many other cardiovascular and respiratory diseases are associated with smoking, and the course of these diseases is not always studied in the context of smoking cessation versus continued smoking. This review summarises the latest available data on health benefits of smoking cessation with focus on both common and infrequent cardiovascular and respiratory diseases.

Improved patient outcome with smoking cessation: when is it too late?

Smoking is the leading modifiable risk factor for chronic obstructive pulmonary disease (COPD), cardiovascular disease (CVD), and lung cancer. Smoking cessation is the only proven way of modifying the natural course of COPD. It is also the most effective way of reducing the risk for myocardial infarction and lung cancer. However, the full benefits of tobacco treatment may not be realized until many years of abstinence. All patients with COPD, regardless of severity, appear to benefit from tobacco treatment. Similarly, patients with recent CVD events also benefit from tobacco treatment. The risk of total mortality and rate of recurrence of lung cancer is substantially lower in smokers who manage to quit smoking following the diagnosis of early stage lung cancer or small cell lung cancer. Together, these data suggest that tobacco treatment is effective both as a primary and a secondary intervention in reducing total morbidity and mortality related to COPD, CVD, and lung cancer. In this paper, we summarize the evidence for tobacco treatment and the methods by which smoking cessation can be promoted in smokers with lung disease.

Pathology of small airways disease

CONTEXT

The term small airways disease encompasses a generally poorly understood group of lung diseases that may arise primarily within the small airways or secondarily from diseases primarily affecting the bronchi or lung parenchyma. Their histology may be confusing; however, because treatments and prognoses vary, correct pathologic diagnosis is important.

OBJECTIVE

To present a nonexhaustive review of the pathology of primary and secondary small airways diseases, including small airways disease related to tobacco; to various other exposures, including mineral dusts; to diseases involving other areas of the lung with secondary bronchiolar involvement; and to recently described bronchiolitic disorders.

DATA SOURCES

Current literature is reviewed.

CONCLUSIONS

Small airways diseases include a wide variety of diseases of which the pathologist must consider. Uncommon conditions such as diffuse idiopathic neuroendocrine cell hyperplasia and diffuse panbronchiolitis may show relatively specific diagnostic features histologically; however, most small airways diseases exhibit nonspecific histologic features. Conditions not considered primary pulmonary diseases, such as collagen vascular diseases, bone marrow transplantation, and inflammatory bowel disease, must also be considered in patients with small airways changes histologically. Clinical and radiologic correlation is important for obtaining the best possible diagnosis.

Small Airways Disease

Small airways diseases are best defined pathologically as a diverse group of conditions that primarily involve bronchioles and acartilagenous airways 2 mm or less in diameter, which include membranous bronchioles, respiratory bronchioles, and alveolar ducts. Small airways can be involved with disease primarily or secondarily. The concept of small airways disease varies among specialties, with clinicians generally considering them in terms of terminal airway changes causing airflow obstruction, radiologists considering them in the context of direct signs and indirect signs identified on high-resolution computed tomography scans, and pathologists evaluating them based entirely or almost entirely on the histologic changes present in the bronchioles, with or without associated changes involving bronchi and alveoli. The histologic features of small airways diseases may be confusing because they overlap. There may be incomplete assessment of the histologic process with limited biopsy. Other disease processes may occur along with a small airways disease, and may obscure or confound its histologic features. This article focuses on the histologic changes diagnostic of a variety of primary and secondary small airways diseases. Because the histologic features involve bronchioles, gross findings are often minimal and/or nonspecific. The article provides a nonexhaustive examination of conditions and diseases involving the small airways, focusing on the microscopic features, with emphasis on the limitations of histologic diagnosis and differential diagnosis.

BAL in the diagnosis of smoking-related interstitial lung diseases: review of literature and analysis of our experience

The group of interstitial lung diseases (ILDs) is formed by respiratory tract disorders, whose aetiology is unknown in the majority of cases, the clinical course differs and the prognosis is generally serious. Some of the ILDs have a potential relation to tobacco smoking and are known as smoking-related ILDs (sr-ILD). Bronchoalveolar lavage fluid (BALF) examination is one of the initial procedures in the diagnosis of ILD. Despite the fact that histological confirmation is the gold standard in ILD diagnosis in many studies, the number of reported biopsies was low. In this review we present the results of BALF examinations of patients with sr-ILD and discuss their value in the differential diagnosis with other types of ILD. An extremely high total cell count (about 50 x 10(6) cells) with significant predominance of pigmented alveolar macrophages is a characteristic pattern of BALF in sr-ILD. The greatest challenge in BALF cytology interpretation is to distinguish sr-ILD and idiopathic pulmonary fibrosis (IPF). IPF is characterised by an elevated proportion and absolute count of lymphocytes and neutrophils; in addition, BALF lymphocytosis is higher in non-specific interstitial pneumonia than in usual interstitial pneumonia (UIP). The population of alveolar macrophage of patients with sr-ILD differs markedly from the foamy and vacuolated cells that predominate in IPF/UIP. Thus, the absence of pigmented cells rather excludes sr-ILD and indicates other types of ILD. To summarise, the place of BALF in the diagnosis of sr-ILD seems to be established.

The effects of secondhand smoke exposure on HRCT findings among asbestos-exposed workers

OBJECTIVES

There is evidence suggesting that secondhand smoke (SHS) exposure is causally linked to adverse respiratory effects. We examined the relations between the exposure to SHS and radiological signs in chest high-resolution computed tomography (HRCT).

METHODS

Asbestos-exposed workers (n=633) were imaged with HRCT, primarily to investigate potential occupational lung disease. After excluding current smokers, the study population included 361 ex- and 141 never-smokers. They answered a questionnaire on occupational exposures, smoking habits and SHS exposure. HRCT images were assessed for emphysema, ground-glass, irregular/linear and rounded opacities, honeycombing and several other signs. Regression analyses were adjusted for asbestos exposure, ex-smoking, age, body mass index and potential reader effect.

RESULTS

Due to missing data the multivariate analyses were restricted to 310 participants aged 47.5-87.0 years. Their lifetime SHS exposure ranged between 0 and 193.5 pack-years (mean 23.5), and exposure in the past 12 months 0-30 packs (0.43). Total (B=0.005, 95% confidence intervals (95% CI) 0.002-0.008, p=0.000) and workplace (B=0.006, 95% CI 0.003-0.009, p=0.001) cumulative SHS exposures were significantly related to ground-glass opacities. Total SHS exposure in the last 12 months (B=0.027, 95% CI 0.000-0.054, p=0.048) and workplace exposure (B=0.027, 95% CI 0.000-0.054, p=0.048) were also significantly related to ground-glass opacities. Positive effects of SHS were also detected on irregular/linear opacities.

CONCLUSIONS

SHS exposure in the last 12 months and over lifetime significantly increases ground-glass opacity in HRCT, suggesting an early or subclinical desquamative interstitial pneumonia/respiratory bronchiolitis. This study further supports that SHS has adverse effects on the lungs that can be detected by X-ray methods.

High-resolution chest tomography in idiopathic pulmonary fibrosis and nonspecific interstitial pneumonia: utility and challenges

PURPOSE OF REVIEW

High-resolution computed tomography (HRCT) scan is regarded as the imaging modality of choice to evaluate patients with known or suspected interstitial lung disease. With current technology, HRCT allows for detailed assessment of interstitial compartments. We examine recent data on its role in the diagnostic evaluation, clinical decision-making, and prognosis of patients with interstitial lung disease, and we highlight the challenges related to its application in this field.

RECENT FINDINGS

HRCT findings are either diagnostic or strongly suggestive of underlying pathologic patterns. By identifying the presence of certain characteristics, radiologists have developed a clearer understanding of HRCT patterns that coincide with underlying pathology. Challenges and controversies still remain, however. For example, recent studies indicate that the diagnostic accuracy and performance characteristics of HRCT depend predominantly on the study setting; intra-observer and inter-observer variability are less between academic radiologists than between community radiologists. Despite this, clinicians tend to rely primarily on HRCT when a radiologic pattern characteristic for histologic usual interstitial pneumonia is identified.

SUMMARY

Specific HRCT patterns help to differentiate and prognosticate different interstitial lung diseases. It is important for clinicians to understand the utility and limitations of HRCT in managing their patients. A multidisciplinary approach remains the gold standard.