Human pathology
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This study reports the presence of surprisingly frequent and often severe interstitial fibrosis in cigarette smokers with no clinical evidence of interstitial lung disease. Twenty-three lobectomy specimens excised for neoplasms, including 20 from smokers, were extensively sampled, and examined semi-quantitatively for interstitial fibrosis, fibroblast foci, peribronchiolar metaplasia, honey-comb change, emphysema, and respiratory bronchiolitis. Interstitial fibrosis involving greater than 25% of slides was identified in 12 of 20 smokers (60%), but in none of the three never-smokers. ⋯ These observations highlight the spectrum of unexpected fibrosis that is frequently encountered in lobectomy specimens from cigarette smokers. Additional investigation will be required to determine the clinical significance of smoking-related interstitial fibrosis and its relationship, if any, to other smoking-related diseases. It is important, however, that smoking-related interstitial fibrosis be distinguished from specific forms of fibrosing lung disease that may be associated with poor prognoses, especially usual interstitial pneumonia.