A 56-year-old non-smoking woman presents with 2 years of progressive dry cough, exertional dyspnea, and marked weight loss. Examination reveals a characteristic flattened thorax (platythorax) with fine inspiratory crackles over the upper posterior chest. She has had two episodes of spontaneous pneumothorax requiring drainage. High-resolution CT shows biapical pleural thickening with subpleural fibroelastosis concentrated in the upper lobes. Spirometry is shown in the diagram. The FEV1/FVC ratio marked **C** is 0.88 (preserved/elevated). What does this preserved FEV1/FVC ratio in the context of markedly reduced FVC and DLCO indicate about the pattern of lung dysfunction in this patient?
A. Mixed obstructive-restrictive pattern indicating small airway disease as the primary pathology
B. Obstructive airway disease with concurrent parenchymal involvement requiring bronchodilator therapy
C. Severe restrictive physiology with preserved airflow dynamics, characteristic of pleuroparenchymal fibroelastosis
D. Preserved FEV1/FVC ratio with reduced FVC suggests emphysematous changes in the upper lobes
Explanation
Why "Severe restrictive physiology with preserved airflow dynamics, characteristic of pleuroparenchymal fibroelastosis" is right
In pleuroparenchymal fibroelastosis (PPFE), the pathophysiology involves elastic fiber deposition in the visceral pleura and subpleural parenchyma, causing alveolar collapse and severe restriction. The preserved FEV1/FVC ratio (0.88, normal >0.70) despite markedly reduced FVC (52%) and FEV1 (58%) is the hallmark spirometric pattern of pure restrictive disease. The disproportionate reduction in DLCO (45%) reflects the severe parenchymal fibrosis and elastic remodeling. This pattern—normal or elevated FEV1/FVC with reduced absolute volumes—distinguishes restrictive from obstructive physiology and is pathognomonic for PPFE in this clinical context (ATS/ERS Classification, AJRCCM 2013).
Why each distractor is wrong
Obstructive airway disease with concurrent parenchymal involvement requiring bronchodilator therapy: PPFE is purely restrictive; the preserved FEV1/FVC ratio explicitly excludes obstruction. Airway obstruction would lower the FEV1/FVC ratio below 0.70. Bronchodilators are not indicated in restrictive disease.
Mixed obstructive-restrictive pattern indicating small airway disease as the primary pathology: A mixed pattern would show a reduced FEV1/FVC ratio (typically <0.70). The preserved ratio here rules out any obstructive component as the primary pathology.
Preserved FEV1/FVC ratio with reduced FVC suggests emphysematous changes in the upper lobes: Emphysema is an obstructive process and would lower the FEV1/FVC ratio. PPFE is characterized by fibroelastosis and architectural distortion, not emphysema, and the CT findings show pleural thickening and fibrosis, not air trapping.
High-YieldNEET PG
In restrictive lung disease, FEV1/FVC is normal or elevated; in obstructive disease, it is reduced. PPFE presents with severe restriction (low FVC, low TLC) but preserved airflow dynamics (normal FEV1/FVC).
ATS/ERS Classification of Idiopathic Interstitial Pneumonias, AJRCCM 2013
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