TOPIC: Diffuse Lung Disease TYPE: Medical Student/Resident Case Reports INTRODUCTION: A 56 year old Hispanic woman with a history of asthma presented with five days of progressive dyspnea and hemoptysis. CASE PRESENTATION: Two months prior, she was treated for COVID-19 complicated by intermittent hemoptysis. Subsequently, her hemoptysis gradually worsened resulting in dyspnea on exertion and hypoxia (SpO2 88%). At presentation, she was febrile (100.8 F), tachycardic (141 bpm), tachypneic (36 breaths/min) and hypoxic (SpO2 85%). Exam was notable for coarse breath sounds and crackles on auscultation. Labs were notable for hemoglobin 6.7 g/dL and a negative SARS-CoV-2 PCR test. Chest CT showed extensive ground-glass and reticular opacities (upper lungs) and a cluster of air cysts (left lower lobe). The imaging findings in conjunction with frank hemoptysis and acute hypoxemic respiratory failure were concerning for diffuse alveolar hemorrhage (DAH). Bronchoscopy showed bloody secretions throughout the airway. Serial lavage aliquots returned progressively bloodier washings confirming DAH. She received empiric antibiotics with subsequent unremarkable infectious workup. She also received pulse dose steroids and underwent an autoimmune workup notable for: positive ANA (1:40), positive p-ANCA (1:1280), and positive MPO IgG (106 AU/mL) concerning for ANCA-associated vasculitis (AAV). Hospital course was complicated by intermittent fevers, hemoptysis, and hypoxia - likely progression of DAH secondary to her vasculitis. She was started on intravenous steroids and cyclophosphamide with resolution of hemoptysis and hypoxia. Post discharge, her rheumatological workup was negative for anti-cardiolipin antibodies, phosphatidylserine autoantibodies, beta-2 glycoprotein I antibodies, and DRVVT screen. DISCUSSION: DAH is a life-threatening condition that commonly presents with fever, cough, and dyspnea while hemoptysis may be absent in a third of patients. Bronchoscopic evaluation reveals progressively bloodier aliquots during lavage as noted in our patient. Treatment warrants addressing the underlying etiology, which may be cessation of the inciting drug, treatment of infection, or glucocorticoids for vasculitides. SARS-CoV-2 infection can directly cause DAH by inciting pulmonary endothelialitis. In contrast, our patient had a positive autoimmune workup for AAV, which was thought to be the immediate cause of her DAH. Without prior systemic manifestations of AAV (rash, arthritis, renal disease), either the patient developed AAV triggered by SARS-CoV-2 infection, or she had asymptomatic AAV that manifested due to the infection. There are multiple reports of COVID-19 predisposing to the development of autoimmune diseases, such as GBS and vasculitides, by triggering chronic inflammation. CONCLUSIONS: We hypothesize that our patient likely developed DAH because the infection led to ANCA-associated vasculitis that manifested as DAH rather than directly damaging her pulmonary blood vessels. REFERENCE #1: Lara AR, Schwarz MI. Diffuse alveolar hemorrhage. Chest. 2010;137(5):1164-1171. doi:10.1378/chest.08-2084 DISCLOSURES: No relevant relationships by Daniel Bouland, source=Web Response No relevant relationships by Elizabeth Epstein, source=Web Response Public Stock holder relationship with Cormedix Please note: 01/2021 Added 04/27/2021 by Vineet Gupta, source=Web Response, value=Purchased stock from market Public Stock holder relationship with Athenix Please note: 02/2021 Added 04/27/2021 by Vineet Gupta, source=Web Response, value=Purchased stock from market Public Stock holder relationship with Kinishka Please note: 02/2021 Added 04/27/2021 by Vineet Gupta, source=Web Response, value=Purchased stock from market Public Stock holder relationship with Novavax Please note: 03/2021 Added 04/27/2021 by Vineet Gupta, source=Web Response, value=Purchased stock from market No relevant relationships by Tonya Lee, source=Web Response No relevant relationships by Priya Sharma, source=Web Response No relevant relationships by Edward Wang, source=Web Re ponse