Original contributionClinically occult interstitial fibrosis in smokers: classification and significance of a surprisingly common finding in lobectomy specimens
Introduction
In a study initially undertaken to investigate the presence and significance of fibroblast foci in lungs from persons without interstitial lung disease, we were surprised by the frequent finding of interstitial fibrosis of unexpected severity in cigarette smokers. This observation prompted us to undertake a systematic, detailed analysis of nontumorous lung parenchyma in patients undergoing lobectomy for neoplasms to assess the presence and potential significance of fibrosis in this situation. We further examined the relationship of the fibrosis to fibroblast foci, peribronchiolar metaplasia, and honey-comb change as well as to emphysema. Our findings suggest that pathologically significant but clinically unrecognized interstitial fibrosis occurs commonly in cigarette smokers. This fibrosis usually is not classifiable as a named form of interstitial lung disease, but it has distinct histologic features that we term smoking-related interstitial fibrosis (SRIF).
Section snippets
Materials and methods
Twenty-three consecutive patients undergoing lobectomy for malignant neoplasm were identified who consented to additional pathologic analysis of their lung specimens. The study was approved by the institutional review board of SUNY Upstate Medical University. Radiology reports were reviewed and a smoking history obtained directly from the patients prior to surgery. Current smokers were defined as those individuals who were either smoking at the time of surgery or had quit less than 6 months
Results
The main clinical and pathologic features of the 23 cases are summarized in Table 1. There were 15 women and 8 men ranging in age from 52 to 81 years (mean, 65 years). Twenty were smokers, including 10 current smokers and 10 ex-smokers (one of whom was a pipe smoker) who quit from 6 months to 36 years previously (mean, 8.9 years). The mean pack years smoked among the current smokers was 39 (range, 20-60) and among the ex-smokers 38 (range, 16-80). There were 3 never-smokers. The tumors
Discussion
The finding of significant and often extensive interstitial fibrosis on pathological examination in over half of lungs resected for tumors from cigarette smokers is surprising, especially since none had clinical evidence of interstitial lung disease. Fraig et al [1], in a study of RB, noted interstitial fibrosis in over 40% of smokers, but neither the extent or severity were described. Auerbach et al [2] in a microscopic study of over 1800 autopsy lungs reported that the degree of fibrosis
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