Smoking-related interstitial lung diseases

Five simple reasons to discard DIP, or why we should stop calling dolphins big fish

The aim of this review is to explain why the term 'desquamative interstitial pneumonia' (DIP) should be discarded and replaced with modern terminology. Reason 1: DIP is a misnomer. Within a few years after the term was coined, it was shown that the airspace cells in DIP are macrophages not desquamated pneumocytes. Reason 2: As a result of overly simplistic and poorly defined histologic criteria, DIP is currently a mixed bag of smoking-related diseases and unrelated processes in never-smokers. Reason 3: DIP obfuscates the modern concept that smoking causes some forms of parenchymal lung disease. Despite the fact that >80% of cases of DIP are caused by smoking, it is currently classified as a 'smoking-related idiopathic interstitial pneumonia', an oxymoron. Reason 4: The premise that the presence of numerous macrophages within airspaces defines an entity creates problematic histologic overlap with other lung diseases that may feature prominent airspace macrophages. Reason 5: DIP is outdated. It was coined in 1965, when many entities in interstitial lung disease had not been described, smoking-related interstitial lung disease was an unknown concept, computed tomograms of the chest had not been introduced and immunohistochemistry was unavailable. We suggest a way forward, which includes eliminating the term DIP and separating smoking-related lung abnormalities (including accumulation of pigmented airspace macrophages) from cases characterised by numerous non-pigmented macrophages in never-smokers. The laudable goal of smoking cessation is not served well by muddying the relationship between smoking and lung disease with inaccurate, outdated terminology.

Is Smoking an Unfavorable Prognostic Factor for Rheumatoid Arthritis?

Introduction: Smoking is the environmental factor that plays the most important role in the etiology of rheumatoid arthritis and the only one that can be changed. In rheumatoid arthritis patients, smoking results in erosive, rapidly progressive, poor therapeutic response. There are studies suggesting that auto antibodies (rheumatoid factor and anti citrullinated protein antibodies) production is triggered by exposure to smoking, thus contributing to rheumatoid arthritis.

Objectives: In this study we have proposed to analyze the effects of smoking on the rheumatoid arthritis. Methods: We evaluated 285 patients with RA admitted to Department of Rheumatology, Clinical Emergency Hospital “St. Andrew”, Constanţa during January-December 2013. Demographics of patients and data on the onset and progression of RA were followed. We were particularly interested in the data related to the rheumatoid arthritis prognostic factors as they were established and published by the Romanian Rheumatology Society.

Conclusion: Smoking influences the onset of rheumatoid arthritis, the seropositivity, the presence of extraarticular manifestations, the acute phase reactants and the number of swollen joints. We can therefore conclude that smoking is an unfavorable prognostic factor for rheumatoid arthritis, influencing both the onset and its evolution.

Gemcitabine-Related Pneumonitis in Pancreas Adenocarcinoma--An Infrequent Event: Elucidation of Risk Factors and Management Implications

BACKGROUND

Gemcitabine-related pneumonitis (GRP) has been reported relatively frequently for pancreas cancer in the literature; however, underlying risk factors and optimal management remain to be defined. We studied a cohort of patients with GRP and investigated potential predisposing factors in pancreatic cancer patients.

PATIENTS AND METHODS

A total 2440 patients at Memorial Sloan Kettering Cancer Center were identified between January 1, 2000, and December 31, 2012, and were screened for grade 2 or higher GRP in an institutional tumor registry and using an ICD billing code database. Demographic and clinical information was extracted by electronic chart review.

RESULTS

A total of 28 patients (1.1%) with GRP were identified. Incidence of grade 2, 3, and 4 reactions were 7 (25%), 18 (64%), and 3 (11%), respectively. No GRP-related mortality was observed. Twenty-one patients (75%) reported a history of cigarette smoking. Seventeen patients (61%) were alcohol users. Six patients (21%) were either regular or heavy drinkers. Most patients (93%) had either locally advanced or metastatic disease. Three patients (11%) underwent a diagnostic bronchoscopy, and in 1 patient a diagnosis of organizing pneumonia was established. Morbidity was significant; 3 patients (11%) required treatment in the intensive care unit. All hospitalized patients received steroid treatment.

CONCLUSION

GRP is relatively uncommon but incurs significant morbidity. Potential risk factors include advanced-stage disease, along with smoking and alcohol consumption and possibly underlying lung disease. We recommend a high level of clinical alertness regarding the diagnosis, early pulmonary referral, and cessation of gemcitabine on suspicion of GRP.

Imaging diagnosis of interstitial pneumonia with emphysema (combined pulmonary fibrosis and emphysema)

Based on clinical and radiological findings, Cottin defined combined pulmonary fibrosis and emphysema (CPFE) as pulmonary emphysema in the upper lungs and interstitial pneumonia in the lower lungs with various radiological patterns. Pathologic findings of CPFE probably corresponded with diffuse interstitial pneumonia with pulmonary emphysema, emphysema with fibrosis, and the combination of both. We described reported radiological findings of CPFE.

Smoking in trauma patients: the effects on the incidence of sepsis, respiratory failure, organ failure, and mortality

BACKGROUND

There is a high percentage of smokers among trauma patients. Cigarette smoking has been associated with the development of acute lung injury and the adult respiratory distress syndrome in critically ill patients. It is also known that nicotine exerts immunosuppressive and anti-inflammatory effects with chronic use. Trauma patients who are smokers usually go through acute nicotine withdrawal after the traumatic event and during their stay in ICU. How the smoking status and acute nicotine withdrawal affect outcomes after trauma is unknown. This question was addressed in this study by analyzing the incidence of sepsis, septic shock and multiple organ dysfunction syndrome, and other outcomes in smoking and nonsmoking trauma patients.

METHODS

A retrospective cohort of trauma patients who met the criteria was randomly selected from the trauma registry. Individual charts were reviewed to confirm documented smoking status. Criteria for selection included the following: Injury Severity Score >or=20, age 18 to 65 years, hospital length of stay >72 hours. Patients with COPD/emphysema, diabetes mellitus, cardiac disease, malignancy, pregnancy, or steroid use were excluded.

RESULTS

Overall, 327 patient charts were reviewed: 156 smokers and 171 nonsmokers. Men outnumbered women in the smoking group fourfold (p = 0.003 versus nonsmokers). Age, Injury Severity Score, the presence of shock on admission, the type of trauma (blunt or penetrating), ICU and hospital length of stay, and the duration of ventilator support were similar between smokers and nonsmokers. There were no differences in the incidence of sepsis, pneumonia, adult respiratory distress syndrome, or multiple organ dysfunction syndrome. Mortality was low (1.2% in smokers; 0.6% in nonsmokers) and did not differ significantly between the groups.

CONCLUSIONS

The smoking status plays a minimal role in the outcome of healthy trauma patients. This suggests that the acute nicotine withdrawal that usually occurs in critically ill patients has no clinically significant implications after injury.

Rheumatoid arthritis and smoking: putting the pieces together

Besides atherosclerosis and lung cancer, smoking is considered to play a major role in the pathogenesis of autoimmune diseases. It has long been known that there is a connection between rheumatoid factor-positive rheumatoid arthritis and cigarette smoking. Recently, an important gene-environment interaction has been revealed; that is, carrying specific HLA-DRB1 alleles encoding the shared epitope and smoking establish a significant risk for anti-citrullinated protein antibody-positive rheumatoid arthritis. We summarize how smoking-related alteration of the cytokine balance, the increased risk of infections (the possibility of cross-reactivity) and modifications of autoantigens by citrullination may contribute to the development of rheumatoid arthritis.

Smoking-related interstitial lung disease

Pulmonary diseases associated with tobacco smoking are a complex group of disorders ranging from chronic obstructive pulmonary disease (COPD) to lung cancer. Interstitial lung diseases (ILDs) have only recently been linked to smoking. The ILDs related to smoking include respiratory bronchiolitis-associated interstitial lung disease, desquamative interstitial pneumonia, and pulmonary Langerhans cell histiocytosis. The relationship of smoking with each of these entities has been largely established on the weight of epidemiologic evidence. Although they have been retained as distinct and separate conditions in various classifications of interstitial lung diseases, these 3 entities share a number of clinical, radiologic, and pathologic features suggesting that they represent a spectrum of patterns of interstitial lung disease occurring in predisposed individuals who smoke. Evaluation of histologic features, particularly in surgical lung biopsy samples, is important in making the distinction between these disorders. However, even after tissue biopsy, it may sometimes be difficult to clearly separate these entities. The importance of making the distinction between them lies in the different clinical management strategies used. Further experimental evidence, including genetic information, may be important in improving our understanding of these diseases.

The role of inflammation in the pathogenesis of idiopathic pulmonary fibrosis

The role of inflammation in idiopathic pulmonary fibrosis (IPF) is controversial. If inflammation were critical to the disease process, lung pathology would demonstrate an influx of inflammatory cells, and that the disease would respond to immunosuppression. Neither is true. The classic pathology does not display substantial inflammation, and no modulation of the immune system is effective as treatment. Recent data suggest that the pathophysiology of the disease is more a product of fibroblast dysfunction than of dysregulated inflammation. The role of inflammation in disease pathogenesis comes from pathology from atypical patients, biologic samples procured during exacerbations of the disease, and careful examination of biologic specimens from patients with stable disease. We suggest that inflammation is indeed a critical factor in IPF and propose five potential nontraditional mechanisms for the role of inflammation in the pathogenesis of IPF: the direct inflammatory hypothesis, the matrix hypothesis, the growth factor-receptor hypothesis, the plasticity hypothesis, and the vascular hypothesis. To address these, we review the literature exploring the differences in pathology, prognosis, and clinical course, as well as the role of cytokines, growth factors, and other mediators of inflammation, and last, the role of matrix and vascular supply in patients with IPF.

Personalized medicine and proteomics: lessons from non-small cell lung cancer

Personalized medicine allows the selection of treatments best suited to an individual patient and disease phenotype. To implement personalized medicine, effective tests predictive of response to treatment or susceptibility to adverse events are needed, and to develop a personalized medicine test, both high quality samples and reliable data are required. We review key features of state-of-the-art proteomic profiling and introduce further analytic developments to build a proteomic toolkit for use in personalized medicine approaches. The combination of novel analytical approaches in proteomic data generation, alignment and comparison permit translation of identified biomarkers into practical assays. We further propose an expanded statistical analysis to understand the sources of variability between individuals in terms of both protein expression and clinical variables and utilize this understanding in a predictive test.

The smoking gun: many conditions associated with tobacco exposure may be attributable to paradoxical compensatory autonomic responses to nicotine

Tobacco exposure is implicated in many illnesses such as cardiovascular disease and cancer, but the mechanisms underlying these associations are poorly understood. The mechanisms by which tobacco induces pro-sympathetic and pro-inflammatory changes also remain elusive. Some studies have attributed these changes to the direct effects of nicotine, but such findings run counter to the pro-vagal, anti-inflammatory nature of the nicotinic pathway. We hypothesize that the illnesses associated with smoking may be partly attributable to autonomic dysfunction, sympathetic bias, and T helper (Th)2 inflammation induced by a paradoxical compensatory response to intermittent nicotinic exposure. The confusion of interpreting the adrenergia and inflammation associated with nicotine as a primary response instead of a secondary compensation may be explained by the unusually rapid absorption, action, and serum elimination of nicotine. Given the fast action and clearance of nicotine, even heavy smokers spend large portions of the day and the entire night in nicotine withdrawal, at which time rebound sympathetic bias may manifest as a result of desensitization of nicotinic receptors. This may help reconcile why the features observed in smokers such as tachycardia, hypertension, inflammation, insomnia, and anxiety, which are perhaps mistakenly attributed to the direct action of nicotine, are identical to those seen during acute nicotine withdrawal after smoking cessation. On the other hand, delayed responses to cessation of smoking such as weight gain and increased heart rate variability are compatible with reduced sympathovagal ratio and resensitization of nicotinic receptors. Sympathetic bias and the associated Th2 inflammation underlie many systemic diseases. Tobacco-related cancers may be partly attributable to immunomodulatory properties of chronic nicotine exposure by dampening Th1 immunity and enabling tumoral evasion of immune surveillance. Other conditions associated with tobacco exposure may also operate through similar autonomic and immune dysfunctions. Therapeutic implications are discussed.

Current concepts in the classification of interstitial lung disease

The diagnosis and classification of idiopathic interstitial pneumonias continue to be problematic areas for pathologists. The recently proposed American Thoracic Society/European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias defines specific clinical, radiologic, and pathologic criteria for each of the pulmonary disorders that encompass the idiopathic interstitial pneumonias. In this review, the highlights of this classification are presented, along with recommended guidelines for handling lung biopsy specimens and diagnosing interstitial lung diseases.

Desquamative interstitial pneumonia and respiratory bronchiolitis-associated interstitial lung disease

BACKGROUND

Desquamative interstitial pneumonia (DIP) and respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) are uncommon forms of interstitial lung disease and have been incompletely characterized.

STUDY OBJECTIVES

To further characterize the clinical features and course of subjects with DIP and RB-ILD.

DESIGN

Retrospective study.

SETTING

Tertiary care, referral medical center.

PATIENTS

Twenty-three subjects with DIP and 12 subjects with RB-ILD seen over a 12-year period between 1990 and 2001.

INTERVENTIONS

None.

RESULTS

The study population included 19 men (54%) and 16 women (46%). The mean (+/- SD) age at diagnosis was 46 +/- 10 and 43 +/- 7 years, respectively, for patients with DIP and RB-ILD. All subjects were either current or previous smokers except for three subjects with DIP. The diagnosis was confirmed in all cases by surgical lung biopsy. Bronchoscopy with transbronchial lung biopsy had been performed in 12 patients and was nondiagnostic in all. The most common pulmonary function abnormality was a reduced diffusing capacity of the lung for carbon monoxide. A CT scan of the chest revealed ground-glass opacities bilaterally in most patients who had DIP and RB-ILD. No differences were observed between subjects with DIP and RB-ILD with respect to clinical features, radiologic findings, or pulmonary function test results. The clinical course was characterized by relative stability in the majority of patients in both groups and a partial response to corticosteroid therapy. Five deaths were observed, including three resulting from progressive diffuse lung disease, all in subjects with DIP.

CONCLUSIONS

We concluded that DIP and RB-ILD are chronic disease processes that in most patients are related to smoking. Persistent abnormalities can be seen on pulmonary function testing and radiologic studies despite smoking cessation and corticosteroid therapy. Corticosteroid therapy appeared to be associated with modest clinical benefit but usually not with resolution of disease. Progressive disease with eventual death can occur in subjects with DIP, especially with continued cigarette smoking.

Desquamative interstitial pneumonia, respiratory bronchiolitis and their relationship to smoking

AIMS

Respiratory bronchiolitis (RB) and desquamative interstitial pneumonia (DIP) are closely associated histological patterns of interstitial pneumonia, although there are no studies on the extent of individual histological parameters. Furthermore, the term smoking related-interstitial lung disease (SR-ILD) has been proposed as a term to encompass patients with both these histological patterns who give a history of smoking, though it is not well defined how this term relates to historical cases of DIP. The aim of this study was to compare histological parameters in cases of DIP and RB and then to review in detail clinical, imaging and histological data for DIP in relation to a history of smoking.

METHODS AND RESULTS

Forty-nine cases were reviewed, 24 with RB and 25 with DIP; five cases of DIP were re-classified as RB on review due to bronchocentricity of the infiltrate. There was a significantly greater extent of interstitial fibrosis (P = 0.02), lymphoid follicles (P < 0.001) and eosinophilic infiltration (P < 0.0001) in patients with DIP compared with RB. In addition, the extents of these three parameters were significantly interrelated. Patients with DIP had a lower incidence of smoking (60%) when compared with patients with RB-ILD (93%) (P < 0.005). Further analysis of smokers versus never-smokers with DIP showed no difference in histological parameters, extent of haemosiderin deposition or the number of CD1a+ macrophages between the two groups, nor were there any differences in clinical data to suggest other aetiologies. Follow-up high-resolution computed tomography data from patients with DIP suggested that a pattern of fibrotic non-specific interstitial pneumonia (NSIP) may develop in the long term in both smokers and never-smokers.

CONCLUSION

There are significant differences in the extent of interstitial fibrosis, lymphoid follicles and eosinophilic infiltration between DIP and RB, as well as a much lower incidence of smoking in patients with DIP. Whether the lower reported incidence of smoking in DIP reflects referral bias or conservatism in giving a history of smoking remains uncertain, as neither histological parameters nor clinical data indicate a difference between smokers and never-smokers with DIP. Nevertheless, some cases of DIP are likely to remain idiopathic and unrelated to RB, though still have a good prognosis. Furthermore, they may evolve into a pattern resembling fibrotic NSIP. Therefore, whilst SR-ILD is appropriate in the correct clinical setting, the distinction between the histological patterns of RB and DIP remains appropriate.

Cigarette smoking in interstitial lung disease: concepts for the internist

Cigarette smoking is a common cause of lung disease. It is clearly implicated in the development of chronic obstructive pulmonary disease and lung cancer. Importantly, cigarette smoking has also been implicated in the development of interstitial lung diseases such as respiratory bronchiolitis interstitial lung disease, desquamative interstitial pneumonia, pulmonary Langerhans' cell histiocytosis,and idiopathic pulmonary fibrosis. The exact role of cigarette smoking in the development of interstitial lung diseases is still being defined; the relatively low prevalence of interstitial lung disease makes epidemiologic studies difficult.

Desquamative Interstitial Pneumonia and Hepatitis C Virus Infection: A Rare Association

Extrahepatic manifestations of hepatitis C virus (HCV) infection are common. The authors report the unusual occurrence of desquamative interstitial pneumonia (DIP) in a patient with HCV. An immunologic response to HCV infection may have a role in the pathogenesis of DIP in patients with chronic HCV. Since DIP is treatable, HCV patients with pulmonary infiltrates should be thoroughly investigated for this disorder. In our experience, the use of steroids in HCV-associated DIP improved the patient's respiratory status without increasing the viral load.

The epidemiology of interstitial lung disease and its association with lung cancer

The criteria and terminology for diagnosing interstitial lung disease (ILD), a diverse range of pulmonary fibrotic disorders that affect the alveoli of the lungs, have been variable and confusing; however, there have been recent major improvements to an internationally agreed classification. Evidence from recent analyses of populations suggests that the incidence and prevalence rates of ILD are on the increase, particularly when the broad definition of ILD is used. In most patients with ILD a cause is not identified; nevertheless, among the established causes are a number of drug therapies and infections. Occupational causes are lessening in importance, while cigarette smoking is now an established risk factor. Radiation therapy for cancer is a well-established cause of ILD that usually, but not always, localises within the radiation portal and may occur later after completion of therapy. Similarly, exposure to drugs long after radiation therapy may be an aetiological factor for the development of ILD later in life, although the magnitude of this risk requires further epidemiological investigation. The possibility that ILD and lung cancer are associated has been recognised for >50 years, but it remains unclear whether ILD precedes lung cancer or vice versa. In this review, we examine the epidemiology of ILD and the basis for its association with lung cancer.

Pneumothorax in pulmonary Langerhans cell histiocytosis

BACKGROUND

Pulmonary Langerhans cell histiocytosis (PLCH) is a smoking-related interstitial lung disease characterized by development of cystic changes that predispose to occurrence of pneumothorax.

STUDY OBJECTIVES

To determine the frequency, recurrence rate, and optimal management of pneumothorax associated with PLCH.

DESIGN

Retrospective study.

SETTING

Tertiary care, referral medical center.

PATIENTS

One hundred two adults >or= 18 years old with histologically confirmed PLCH seen at Mayo Clinic Rochester over a 23-year period from 1976 to 1998.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Sixteen of 102 patients (16%) with PLCH had pneumothorax; mean age at the time of diagnosis was 29.4 years (range, 18 to 52 years), and all had smoked cigarettes. There were 37 episodes of pneumothoraces (1 to 5 episodes per patient); 10 patients (63%) had more than one episode. Median age at diagnosis of PLCH was significantly younger in patients with pneumothorax when compared to those without pneumothorax (27 years vs 41.5 years, p < 0.001), but pulmonary function parameters and survival after diagnosis were not significantly different. Rate of recurrent pneumothorax was 58% to the ipsilateral side when the episode was managed by observation or chest tube without pleurodesis, and 0% after surgical management with pleurodesis.

CONCLUSIONS

These data support the early use of surgical therapy with pleurodesis in managing patients with PLCH and spontaneous pneumothorax.

Bronchiolar disorders

Bronchiolar abnormalities are relatively common and occur in a variety of clinical settings. Various histopathologic patterns of bronchiolar injury have been described and have led to confusing nomenclature with redundant and overlapping terms. Some histopathologic patterns of bronchiolar disease may be relatively unique to a specific clinical context but others are nonspecific with respect to either etiology or pathogenesis. Herein, we present a scheme separating (1) those disorders in which the bronchiolar disease is the predominant abnormality (primary bronchiolar disorders) from (2) parenchymal disorders with prominent bronchiolar involvement and (3) bronchiolar involvement in large airway diseases. Primary bronchiolar disorders include constrictive bronchiolitis (obliterative bronchiolitis, bronchiolitis obliterans), acute bronchiolitis, diffuse panbronchiolitis, respiratory bronchiolitis, mineral dust airway disease, follicular bronchiolitis, and a few other rare variants. Prominent bronchiolar involvement may be seen in several interstitial lung diseases, including hypersensitivity pneumonitis, respiratory bronchiolitis-associated interstitial lung disease, cryptogenic organizing pneumonia (idiopathic bronchiolitis obliterans organizing pneumonia), and pulmonary Langerhans' cell histiocytosis. Large airway diseases that commonly involve bronchioles include bronchiectasis, asthma, and chronic obstructive pulmonary disease. The clinical relevance of a bronchiolar lesion is best determined by identifying the underlying histopathologic pattern and assessing the correlative clinico-physiologic-radiologic context.

Effects of cigarette smoke on the immune system

Although the health risks of tobacco smoking are well documented, there is increasing evidence that smokers have a lower incidence of some inflammatory and neurodegenerative diseases. Many of the adverse and beneficial effects of smoking might result from the ability of cigarette smoke to suppress the immune system. Nicotine, which is one of the main constituents of cigarette smoke, suppresses the immune system but might have therapeutic potential as a neuroprotective and anti-inflammatory agent.

Influence of cigarette smoking on disease outcome in rheumatoid arthritis

Cigarette smoking is a well-known risk factor for rheumatoid arthritis. However, the influence of smoking on disease outcome has only been investigated very recently, and the data are not clear-cut. Smoking has a number of important effects on the immune system and sex hormones that may influence disease pathogenesis. Smoking has also been shown to affect disease outcome in other inflammatory diseases. The major focus of this review is to explore the relationship between smoking and severity of rheumatoid arthritis in detail.

Clinical outcomes of pulmonary Langerhans'-cell histiocytosis in adults

BACKGROUND

Pulmonary Langerhans'-cell histiocytosis is an uncommon interstitial lung disease in adults. It has an unpredictable course and may be associated with an increased susceptibility to the development of malignant neoplasms.

METHODS

We reviewed the records of 102 adults with histopathologically confirmed pulmonary Langerhans'-cell histiocytosis to ascertain their vital status and whether cancer had been diagnosed. The health status of surviving patients was quantified with the use of the 36-Item Short-Form General Health Survey. Factors potentially associated with survival after the diagnosis of pulmonary Langerhans'-cell histiocytosis were analyzed with the Cox proportional-hazards model.

RESULTS

The median follow-up period was 4 years (range, 0 to 23). There were 33 deaths, 15 of which were attributable to respiratory failure. Six hematologic cancers were diagnosed. The overall median survival was 12.5 years, which was significantly shorter than that expected for persons of the same sex and calendar year of birth (P<0.001). In a univariate analysis, variables predictive of shorter survival included an older age (P=0.003), a lower forced expiratory volume in one second (FEV1) (P=0.004), a higher residual volume (P=0.007), a lower ratio of FEV1 to forced vital capacity (P=0.03), and a reduced carbon monoxide diffusing capacity (P=0.001).

CONCLUSIONS

The survival of adults with pulmonary Langerhans'-cell histiocytosis is shorter than that in the general population, and respiratory failure accounts for a substantial proportion of deaths among such patients.

Heterogeneity of pulmonary fibrosis: interstitial pneumonias and sarcoidosis

This review focuses on two representatives of pulmonary fibrosis. One is usual interstitial pneumonia lesion, typically seen in patients with idiopathic pulmonary fibrosis. The other is parenchymal fibrosis along the bronchovascular bundles, observed in patients with sarcoidosis. Both are intractable fibrosis amenable only to lung transplantation. The authors trace the historical classification of idiopathic interstitial pneumonia, discuss interstitial pneumonia associated with collagen vascular diseases and occupational exposure, and review the most important issues to clarify both types of pulmonary fibrosis.