Smoking is one of leading causes of preventable early mortality/morbidity, worldwide. Cigarette smoke is complex mixture of more than 4000 components, of which about 200 are carcinogens, have been associated with numerous diseases involving entire body/systems. Since cigarette smoke is inhaled, it is inevitable that it will have significant effects on respiratory system. Inhalation of cigarette smoke causes many diseases associated with lung-respiratory tract/particularly chronic obstructive pulmonary disease/lung cancer. Among them, interstitial lung diseases are, also, important.
Interstitial lung disease is heterogeneous group of diseases affecting pulmonary interstitial tissues, usually presenting with dyspnea or non-productive cough, causing restrictive pulmonary function test pattern/gas diffusion restriction. It may present with diffuse parenchymal involvement.
Smoking-related interstitial lung diseases (SR-ILD) include; respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), desquamative interstitial pneumonia (DIP), pulmonary langerhans cell histiocytosis (PLCH), idiopathic pulmonary fibrosis (IPF), combined pulmonary fibrosis and emphysema (CPFE), pulmonary alveolar proteinosis (PAP), Goodpasture syndrome and diffuse alveolar hemorrhage (G-DAH), rheumatoid arthritis related interstitial lung disease (RA-ILD) and acute eosinophilic pneumonia (AEP). We will discuss this wide-ranged disease spectrum under 6 main titles with case-based format.
RB-ILD, DIP, PLHH, which constitute first three titles, have been shown to have strong, definite epidemiological relationships with smoking.
The relationship between smoking and IPF has been suspected for many years, this association has been proven in recent studies. In series of IPF patients, prevalence of smoking was found to be between 41-83%. In one of multicenter case control study, it was observed that risk of developing IPF was increased with history of smoking, odds ratio was 1.6.
CPFE, which is described as association of emphysema in upper lobes and fibrosis in lower lobes, is recently defined smoking related syndrome. This disease is seen in almost entirely male patients, in their 6th/7th decades. Moreover, 98% of CPFE was observed in active/old smokers. CPFE is characterized by relative preservation of lung volume despite impaired diffusion capacity/fibrotic changes
Although there are publications about association of PAP, G-DAH, RA-ILD and AEP with smoking, accuracy of scientific evidence is lower than above-mentioned five diseases. Additionally, cause-effect relationship has not been clearly demonstrated in some studies. Therefore, these diseases will be examined under title of '' Other smoking-related interstitial lung diseases''.
The aims of this study are to examine characteristic imaging findings of SR-ILD, to give insight to radiologist for diagnosing accurately, to emphasize that SR-ILD should be included in differential diagnosis in patients with smoking-history with complaints of dyspnea or non-productive cough, to emphasize the importance of interdisciplinary cooperation between departments of chest diseases, radiology and pathology in equivocal situations.