A 25-year-old, previously healthy man comes to the office due to 3 months of progressive dyspnea and nonproductive cough. The patient feels short of breath when cycling 2 miles to his office, which he could do without difficulty in the past. He does not use tobacco or alcohol. The patient works at a publishing firm in New York and has not traveled recently. Family history is significant for asthma in his father. Temperature is 36.7 C (98.1 F), blood pressure is 130/80 mm Hg, pulse is 78/min, and respirations are 16/min. Pulse oximetry is 97% on room air. The lungs are clear on auscultation and heart sounds are normal. Laboratory results are as follows:
Chest x-ray shows mediastinal fullness and scattered reticular opacities in the upper lungs. Which of the following pulmonary function test patterns is most likely to be observed in this patient?

Question

A 25-year-old, previously healthy man comes to the office due to 3 months of progressive dyspnea and nonproductive cough.  The patient feels short of breath when cycling 2 miles to his office, which he could do without difficulty in the past.  He does not use tobacco or alcohol.  The patient works at a publishing firm in New York and has not traveled recently.  Family history is significant for asthma in his father.  Temperature is 36.7 C (98.1 F), blood pressure is 130/80 mm Hg, pulse is 78/min, and respirations are 16/min.  Pulse oximetry is 97% on room air.  The lungs are clear on auscultation and heart sounds are normal.  Laboratory results are as follows: 
Chest x-ray shows mediastinal fullness and scattered reticular opacities in the upper lungs.  Which of the following pulmonary function test patterns is most likely to be observed in this patient?

Quizplus · Accepted Answer

11ec25c8_d138_7ddb_bc81_6398fe2bde8c_MD0003_00 This patient's presentation is consistent with sarcoidosis, a systemic, granulomatous disorder of unknown etiology that commonly involves the lungs. Clues to the diagnosis include the patient's hypercalcemia (due to vitamin D conversion by lung macrophages) and chest x-ray findings suggesting hilar lymphadenopathy (described as mediastinal fullness and scattered reticular opacities in the upper lobe). Lung examination is often normal; patients may have only mild symptoms. Sarcoidosis can result in abnormal pulmonary function tests (PFTs) in up to 70% of patients. Granuloma-induced scarring and fibrosis result in the typical restrictive pattern (ie, normal or reduced FEV1, normal or reduced FVC, normal or increased FEV1/FVC ratio, reduced total lung capacity [TLC]). The inflammation and scarring intrinsically impede alveolar gas exchange, leading to decreased diffusion capacity for carbon monoxide (DLCO). Among patients demonstrating restrictive physiology on PFTs, the findings for DLCO help differentiate intrinsic lung disease (eg, fibrosis) from extrinsic causes of hypoventilation (eg, chest wall weakness). (Choice A) Obesity-hypoventilation syndrome, in which excess adipose tissue restricts diaphragmatic excursion, can produce PFT results demonstrating restrictive physiology with chest wall weakness. Findings include decreased FEV1 and TLC with preserved DLCO because the physiology of alveolar gas exchange is unaffected. (Choice B) In diffuse pulmonary or alveolar hemorrhage (eg, pulmonary vasculitis), an abnormal increase in hemoglobin within the alveolar space increases carbon monoxide transfer, resulting in increased DLCO. However, lung volumes and airway mechanics are unaffected; therefore, FEV1 and TLC are normal. (Choices D and E) Obstructive lung conditions (eg, asthma, chronic bronchitis, emphysema) result in lung hyperinflation and airway obstruction during exhalation. Expected PFT findings include increased TLC and decreased FEV1. The results for DLCO allow differentiation between chronic obstructive pulmonary disease (COPD) and severe asthma. COPD is associated with reduced DLCO due to alveolar destruction, whereas severe asthma is associated with increased DLCO due to increased thoracic blood flow caused by increased negative intrathoracic pressures during inspiration. Educational objective: Pulmonary function tests in patients with sarcoidosis-associated lung disease typically follow a restrictive pattern: normal or reduced FEV1, normal or reduced FVC, normal or increased FEV1/FVC ratio, reduced total lung capacity, and decreased diffusion capacity for carbon monoxide. References: Pulmonary sarcoidosis. (http://www.ncbi.nlm.nih.gov/pubmed/26593138) Pulmonary fibrosis in sarcoidosis: clinical features and outcomes. (http://www.ncbi.nlm.nih.gov/pubmed/23952859)

A 25-Year-Old, Previously Healthy Man Comes to the Office Due