Winning Abstracts from the 2008 Medical Student Abstract Competition: Non-specific Interstitial Pneumonia, Suspect The Unexpected
Authors: First Author: J Benjamin Robbins, Student; Second Author: Wael El Maraachli, Member
Idiopathic Interstitial Pneumonias can be divided into several subcategories. Some of these subcategories carry a very grim prognosis: 10 year survival of less than 10% in the case of Usual Interstitial Pneumonia. Others which are steroid-responsive, such as Non-specific Interstitial Pneumonia (NSIP), have a 10 year survival of more than 60%. The formidable task of deciphering amongst these subtypes, therefore, becomes paramount.
A 64-year-old woman presented to her physician with worsening shortness of breath and a productive cough. CXR showed bibasilar infiltrates and she was provided unspecified antibiotics with only partial resolution of her symptoms. Two months later, she presented to the same physician with worsening dyspnea on exertion and a dry, nonproductive cough. She was given a 10-day course of trimethoprim-sulfamethoxazole double strength with no improvement of her symptoms. Two weeks later, a 20-day regimen of the same antibiotic was begun. However, her dyspnea worsened and her exercise tolerance became severely compromised over the next week. This prompted an ER visit, where she was found to be hypoxic. On admission, she was tachypneic, and her oxygen saturation was 88% on room air. There were no signs of hypervolemia. Lung examination revealed fine inspiratory and expiratory rales from mid lungs to bases. An ABG revealed a partial pressure of oxygen of 61mm Hg on room air with an elevated alveolar-arterial oxygen gradient of 49 mm Hg. A CXR showed bilateral basilar infiltrates. Chest CT showed bilateral ground-glass opacities and bilateral basilar alveolar-filling defects. An echocardiogram and a workup for atypical pneumonias were both benign. Collagen vascular disease labs were remarkable for Rheumatoid Factor of 18, ESR 36, CRP 2.0, and ANA titer of 1:80, with the rest of the markers all within normal limits. Bronchoalveolar lavage showed no tumor cells. A transbronchial biopsy revealed organizing pneumonia and cellular interstitial pneumonia, but contained insufficient tissue to make a definitive diagnosis. A wedge biopsy showed prominent cellular interstitial pneumonia with only a minor component of organizing pneumonia leading to the diagnosis of NSIP. The patient recently began a trial of steroids.
Dyspnea and cough are two of the most common complaints faced by internists. In this situation, these common complaints led to the diagnosis of an uncommon condition. This case illustrates the importance of having a high index of suspicion for idiopathic interstitial pneumonia in a patient with persistent dyspnea and cough. It further demonstrates the difficulty in teasing out the proper subtype of idiopathic interstitial pneumonia. Internists faced with similar cases should consider the benefit of a chest CT with potential biopsy, which could lead to an earlier diagnosis of a potentially treatable condition.
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