Idiopathic pulmonary fibrosis (IPF) is a progressive and often fatal form of interstitial lung disease. Despite extensive efforts in research during recent years, the mechanisms of the disease remain poorly understood. Evidence of an inflammatory mechanism, both supportive and contrary, is briefly reviewed in this paper. However, growing evidence has indicated that the apoptosis of alveolar epithelial cells (AECs) may be the early driving force of progression, with subsequent disrupted integrity of the alveolar-capillary basement membrane leading to an abnormal wound healing pathway. Thus, this paper will focus on outlining a process of pathogenesis of IPF from initial apoptosis of AECs to end lung remodeling.
Apoptosis ; Epithelial Cells ; pathology ; Humans ; Idiopathic Pulmonary Fibrosis ; etiology ; pathology ; Lung ; pathology

BACKGROUNDCombined emphysema and pulmonary fibrosis, including idiopathic pulmonary fibrosis (IPF), is a distinct disorder described with upper-lobe emphysema and lower-lobe fibrosis on chest computed tomography. Smoking appears to be the predominant risk factor for this disorder. We aimed to compare clinical features, smoking history, physiological and radiological findings between IPF with and without emphysema.

METHODSA sample of 125 IPF patients over a period of 48 months were evaluated. High resolution CT scans were reviewed blinded to clinical data. The IPF patients with or without emphysema were classified accordingly.

RESULTSThe prevalence of emphysema in this IPF sample was 70/125. IPF with emphysema was significantly associated with smoking status (OR 63; 95% CI 4.4 to 915; P = 0.002) and smoking pack year (OR 1.1; 95% CI 1.05 to 1.13; P = 0.000). The patients with IPF and emphysema had a higher decrease in carbon monoxide diffusing capacity adjusted for alveolar volume ((58±19)% pred vs. (66±21)% pred; P = 0.021) and a higher prevalence of pulmonary hypertension (24/70 vs. 7/55; P = 0.006). The two groups of patients had similar forced and residual volumes. No significant differences were found in cell differentials of bronchoalveolar lavage or the scores of fibrosis on chest CT. Survival of the patients with emphysema was significantly less than that of patients with IPF alone.

CONCLUSIONSCigarette smoking induces IPF combined with emphysema. Emphysema further impairs physiological function and increases the prevalence of pulmonary hypertension that leads to poor prognosis. The inclusion of the patients with combined pulmonary fibrosis and emphysema in IPF clinical trials may lead to under evaluation of the effect of treatment in patients.

Aged ; Female ; Humans ; Idiopathic Pulmonary Fibrosis ; etiology ; physiopathology ; Male ; Middle Aged ; Pulmonary Emphysema ; complications ; physiopathology ; Smoking ; adverse effects

OBJECTIVETo review the studies investigating the increased risk of lung cancer in patients with idiopathic pulmonary fibrosis (IPF).

DATA SOURCESData cited in this review were obtained mainly from PubMed and Medline from 1999 to 2013 and highly regarded older publications were also included.

STUDY SELECTIONWe identified, retrieved and reviewed the information on the frequency, risk factors, anatomical features, histological types, clinical manifestations, computed tomography findings and underlying mechanisms of lung cancer in IPF patients.

RESULTSThe prevalence rates of lung cancer in patients with IPF (4.8% to 48%) are much higher than patients without IPF (2.0% to 6.4%). The risk factors for lung cancer in IPF include smoking, male gender, and age. Lung cancers often occur in the peripheral lung zones where fibrotic changes are predominant. Adenocarcinoma and squamous cell carcinoma are the most common types of lung cancer in patients with IPF. Radiologic features of these patients include peripherally located, ill-defined mass mimicking air-space disease. The underlying mechanisms of the development of lung cancer in patients with IPF have not been fully understood, but may include the inflammatory response, epithelial injury and/or abnormalities, aberrant fibroblast proliferation, epigenetic and genetic changes, reduced cell-to-cell communication, and activation of specific signaling pathways.

CONCLUSIONSThese findings suggest that IPF is associated with increased lung cancer risk. It is necessary to raise the awareness of lung cancer risk in IPF patients among physicians and patients.

Age Factors ; Female ; Humans ; Idiopathic Pulmonary Fibrosis ; complications ; epidemiology ; genetics ; Lung Neoplasms ; epidemiology ; etiology ; genetics ; Male ; Risk Factors ; Sex Factors

Occupational and environmental exposure can directly cause specific lung diseases, and can also induce autoimmune diseases that can lead to various types of interstitial lung diseases. In recent years, it was discovered that certain occupational and environmental exposure was related to the increased risk of Idiopathic pulmonary fibrosis (IPF) disease and progression, including metal and mineral dust, wood dust, organic dust, asbestos dust, silica dust, cigarette smoke and air pollution. IPF is a chronic progressive fibrotic lung disease of unknown etiology, with a characteristic imaging and histologic pattern called usual interstitial pneumonia. This article is a review based on the correlation and mechanism of occupational and environmental exposure in the pathogenesis and disease progression of IPF to improve the understanding of the disease and promote the formulation of treatment plans.
Humans ; Idiopathic Pulmonary Fibrosis/etiology* ; Dust ; Environmental Exposure/adverse effects* ; Occupational Exposure/adverse effects* ; Lung Diseases, Interstitial

Evidence suggests that diabetes mellitus (DM) is associated with idiopathic pulmonary fibrosis (IPF). According to the new IPF guidelines, high-resolution computed tomography (HRCT) is an essential means of diagnosing IPF. We investigated the relationship between IPF and DM in patients treated between 2003 and 2007. Newly diagnosed IPF patients in large university teaching hospitals in Korea were enrolled from January 2003 to December 2007. We retrospectively analyzed 1,685 patients using the interstitial lung disease (ILD) registry. In total, 299 IPF patients (17.8%) also had DM. The mean age of our subjects was 68.0 +/- 9.4 yr. HRCT showed significantly more reticular and honeycomb patterns in IPF patients with DM than in IPF patients without DM (P = 0.014, P = 0.028, respectively). Furthermore, significantly higher incidences of hypertension, cardiovascular diseases, and other malignancies (except lung cancer) were found in IPF patients with DM than in IPF patients without DM. In conclusion, IPF patients with DM are more likely to have the usual interstitial pneumonia (UIP) pattern, including reticular and honeycomb patterns, on HRCT than are those without DM.
Aged ; Cardiovascular Diseases/epidemiology/etiology ; Diabetes Mellitus, Type 2/*complications ; Female ; Humans ; Hypertension/epidemiology/etiology ; Idiopathic Pulmonary Fibrosis/complications/*diagnosis/radiography ; Incidence ; Male ; Middle Aged ; Neoplasms/epidemiology/etiology ; Registries ; Republic of Korea/epidemiology ; Retrospective Studies ; Tomography, X-Ray Computed

OBJECTIVETo study the pathologic characteristics of chronic hypersensitivity pneumonitis, especially the pattern of pulmonary interstitial fibrosis; and to compare the histologic features with those of idiopathic interstitial pneumonitis.

METHODSThe HE-stained paraffin sections of 10 cases of chronic hypersensitivity pneumonitis encountered during the period from 2000 to 2008 were retrospectively analyzed.

RESULTSThere were altogether 6 males and 4 females, with age of patients ranging from 23 to 59 years (mean=47.2 years). Clinically, the patients presented with chronic cough and shortness of breath for 4 months to 6 years. Histologically, 7 cases showed usual interstitial pneumonitis (UIP)-like fibrosis. Patchy fibrosis was observed under the pleura, adjacent to interlobular septa and around bronchioles. In all of the 7 cases, foci of fibroblastic proliferation, as well as bronchiolar metaplasia of peribronchiolar alveoli and mild bronchiolitis, were noted. Three cases presented with mild honeycomb changes of lung and 3 cases showed non-specific interstitial pneumonitis (NSIP)-like fibrosis, in which the alveolar septa were expanded by fibrous tissue and collagen, with relative preservation of alveolar architecture. Bronchiolitis and lymphocytic infiltrates in alveolar septa were seen. Schaumann bodies were identified in 1 case. In general, patients with chronic hypersensitivity pneumonitis were younger than patients with idiopathic UIP. Computed tomography often showed upper and middle lobar involvement and mosaic attenuation. Compared with idiopathic UIP, the UIP-like fibrosis of chronic hypersensitivity pneumonitis often occurred not only under the pleura and adjacent to interlobular septa, but also around bronchioles and was accompanied by bronchiolar metaplasia.

CONCLUSIONSChronic hypersensitivity pneumonitis can mimic other types of lung conditions with interstitial fibrosis, especially UIP and NSIP. As a result, some cases of chronic hypersensitivity pneumonitis may be misdiagnosed as such.

Adult ; Alveolitis, Extrinsic Allergic ; complications ; pathology ; Chronic Disease ; Diagnostic Errors ; Female ; Humans ; Idiopathic Pulmonary Fibrosis ; etiology ; pathology ; Lung Diseases, Interstitial ; pathology ; Male ; Middle Aged ; Pulmonary Alveoli ; pathology ; Young Adult