Smoking-related interstitial fibrosis: radiographic morphological comparisons

Smoking-related lung diseases are diverse, but the most difficult to diagnose remain diseases that involve interstitial changes, in some pathologies combined with emphysema. The aim of the research is to compare the X-ray and morphological features of smoking-related interstitial fibrosis (SRIF). Methods. A histological analysis of surgical samples from 119 patients (smokers and ex-smokers) who underwent lobectomy for lung cancer or other focal lesions in the lungs was performed. Results. Twenty seven patients (18 men, 9 women, 4 ex-smokers) with histological signs of SRIF were identified based on the pathology results; the mean age was 69.1 ± 8.9 years, the smoking index (SI) was 42.06 ± 11.8 pack-years. Results. The prevalence of fibrosis, assessed semi-quantitatively by histological examination, was significantly associated with the SI (r = 0.44; p < 0.05). Fibrosis of the interalveolar septa was observed in areas of emphysema; in addition, signs of chronic bronchiolitis were detected in a third of patients, and constrictive bronchiolitis in 2/3 of patients. The presence of emphysema was correlated with the presence of constrictive bronchiolitis (r = 0.67; p < 0.05). In 11 of 27 patients, fibroblastic foci were found in the walls of the respiratory bronchioles, and their presence also correlated with emphysematous changes (r = 0.40; p < 0.05). CT scans revealed signs of emphysema in 80% patients. In addition; polysegmental areas with ground glass opacities were detected in 12/20 patients, reticular and/or cord-like attenuations were detected in 14 patients, and interlobular interstitial thickening was detected in 8 patients. These signs were assessed as “fibrous” when localized in the emphysema zone. When conducting a correlation analysis, a relationship was found between radiologically detected emphysema and fibrotic changes detected by histological examination (r = 0.50), and the prevalence of CT signs of fibrosis correlated with the presence of fibroblastic foci in the bronchiolar wall (r = 0.51). Conclusion. SRIF is more common in individuals with a smoking history of more than 20 pack-years. CT examination does not always identify the signs of SRIF. In our study, signs of emphysema were detected in 80% patients, and signs possibly associated with fibrosis – in less than half of the cases. Histological results suggest that SRIF is the end stage of the respiratory bronchiolitis of smokers.