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A6471 - Hypersensitivity Pneumonitis: Hypoxemia with Normal Chest Imaging
Author Block: M. Naddour1, D. Venkat2, P. Kim2, M. Balaan2; 1Allegheny Health Network, Pittsburgh, PA, United States, 2Allegheny General Hospital, Pittsburgh, PA, United States.
Hypersensitivity pneumonitis (HP) is a complex syndrome with often devastating consequences. Presenting with dyspnea and interstitial pulmonary infiltrates on imaging. We present a case of a 69-year-old male patient presenting with HP with significant hypoxemia and a normal high resolution CT.Case presentation:69-year-old male presented with worsening dyspnea for 6 months. He was a previous 10 pack year with no history of alcohol abuse, illicit drug use, occupational exposure or pets. On physical exam, he was afebrile with diffuse inspiratory crackles. He was noted to require 3L oxygen at rest. Chest X-ray did not show any significant lung pathology. Pulmonary function tests revealed FVC 3.18 L (71% pred), FEV1 1.93 L (54%), FEV1/FVC 61%, TLC 5.2 L (76%), and DLCO 13.0 (54%). HRCT (Figure 1) showed evidence of emphysema with no other pulmonary changes. Transthoracic echocardiogram showed mild pulmonary hypertension to 40-49mmHg. Right heart catheterization showed RA 3/3/2, PA 28/13/21, PaWP 7/7/9 and a Fick Cardiac Index of 3.36. Based on this laboratory data, his hypoxemia and DLCO decrease were out of proportion to the changes in the pulmonary artery pressure and HRCT findings. VATS biopsy was therefore performed, which revealed focal interstitial non-necrotizing granulomas with lymphocytic bronchiolitis consistent with HP. Patient was then treated with prednisone 60mg and Imuran with improvement of his dyspnea. Discussion: Hypersensitivity pneumonitis is an uncommon cause of interstitial lung disease. This disorder is often under-reported and under-diagnosed as a major cause lung disease due to the lack of uniform diagnostic criteria as well as non-descript symptoms.The importance of this diagnosis lies in its subsequent progression and often end stages requiring lung transplantation The scarcity of these cases demonstrates the rarity of this disorder and the immense variety of pathogens present.Treatment must be tailored to the requirements of the patient with no hallmark of treatment.The initial treatment is prevention of exposure to antigens often followed by steroids, although steroids demonstrate no proven efficacy with the ultimate result for these patients often being lung transplant.This case demonstrates a unique situation with chronic dyspnea and no CT findings of interstitial lung disease, proving the importance of open lung biopsy in patients with worsening unexplained hypoxemia.Conclusion: This is a unique case of hypersensitivity pneumonitis with a normal high resolution CT of the chest. Due to the lack of specific diagnostic criteria for this disease, it is important to be aware of HP as a cause of dyspnea