Elsevier

Human Pathology

Volume 41, Issue 3, March 2010, Pages 316-325
Human Pathology

Original contribution
Clinically occult interstitial fibrosis in smokers: classification and significance of a surprisingly common finding in lobectomy specimens

https://doi.org/10.1016/j.humpath.2009.09.003Get rights and content

Summary

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. Three cases were classified as specific forms of interstitial lung disease, including one each of usual interstitial pneumonia, Langerhans cell histiocytosis, and asbestosis. The remaining 9 cases did not fit with a named interstitial lung disease and were considered to represent examples of smoking-related interstitial fibrosis. This lesion was characterized by varying degrees of alveolar septal widening by collagen deposition along with emphysema and respiratory bronchiolitis. The fibrosis occurred both in subpleural and in deeper parenchyma. It surrounded enlarged airspaces of emphysema, but it also involved non-emphysematous parenchyma. Clinical progression was not documented in any case, although follow-up was short. 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.

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

References (13)

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