A 68-year-old retired shipyard worker with 30 years of occupational asbestos exposure presents with mild exertional dyspnea. Chest radiograph shows bilateral calcified pleural plaques with the classic "holly leaf" appearance. Spirometry reveals FVC 78%, FEV1 80%, and the parameter marked **C** (FEV1/FVC ratio) is 0.82. Which of the following best explains the significance of the preserved FEV1/FVC ratio in this clinical context?
A. The preserved ratio excludes obstructive airway disease and indicates a restrictive pattern consistent with pleural plaques alone, without coexistent asbestosis or COPD
B. The preserved ratio confirms malignant mesothelioma development and necessitates immediate chemotherapy initiation
C. The elevated ratio suggests concurrent emphysema from his smoking history and indicates need for bronchodilator therapy
D. The normal ratio indicates that pleural plaques have progressed to visceral pleural involvement with parenchymal fibrosis
Explanation
Why Option 1 is correct
The preserved FEV1/FVC ratio of 0.82 (normal is >0.70) in the setting of reduced FVC and TLC indicates a restrictive pattern without airflow obstruction. This is the hallmark spirometric finding in isolated pleural plaques — the mild reduction in lung volumes (FVC 78%, TLC 75%) reflects limited chest wall expansion and reduced pleural compliance from the plaques themselves, but the normal or elevated FEV1/FVC ratio distinguishes this from obstructive disease (COPD, asthma). According to Murray and Nadel's Textbook of Respiratory Medicine, the spirometric impact of isolated pleural plaques is typically mild restriction (5–15% reduction in FVC and TLC) with preserved gas exchange and normal FEV1/FVC ratio, confirming that the plaques are not causing airway obstruction and that there is no coexistent asbestosis (which would show parenchymal fibrosis on HRCT) or significant COPD.
Why each distractor is wrong
Option 2: An elevated FEV1/FVC ratio does not suggest emphysema; emphysema causes airflow obstruction with a reduced FEV1/FVC ratio. Although the patient is a former smoker, the normal ratio and preserved DLCO (82%) argue against significant emphysematous change. Bronchodilators are not indicated for a restrictive pattern.
Option 3: Visceral pleural involvement and parenchymal fibrosis (asbestosis) would be evident on HRCT as interstitial fibrosis and would produce a more pronounced restrictive pattern with reduced DLCO. The HRCT in this case explicitly shows "no parenchymal fibrosis," and DLCO is preserved at 82%, ruling out asbestosis.
Option 4: Pleural plaques themselves are not premalignant and do not confirm mesothelioma development. While asbestos exposure carries an elevated lifetime risk of mesothelioma (5–10% in heavily exposed individuals), the presence of plaques alone is a biomarker of exposure, not a diagnosis of malignancy. Imaging and clinical surveillance are warranted, but the plaques do not necessitate immediate chemotherapy.
High-YieldNEET PG
Isolated pleural plaques produce mild restriction with preserved FEV1/FVC ratio; an abnormal ratio suggests coexistent obstructive or parenchymal disease, not plaques alone.
Murray and Nadel's Textbook of Respiratory Medicine, 7th ed.
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