S4317 Silent Aspiration: A Rare Case of Lipoid Pneumonia Linked to Chronic Gastroesophageal Reflux Disease

Introduction: Lipoid pneumonia is a rare lung condition which is characterized by the accumulation of lipid-laden macrophages in the alveoli. While typically caused by aspiration of oil-based substances, chronic microaspiration from untreated gastroesophageal reflux disease (GERD) is an infrequent cause. Due to nonspecific symptoms and imaging findings, diagnosis is often delayed. This case highlights the importance of considering GERD-related aspiration in patients with unexplained chronic lung disease. Case Description/Methods: A 72-year-old woman with a history of childhood asthma and untreated GERD presented with a 2- to 3-day history of intermittent hemoptysis, progressively worsening dyspnea, and cough. Eighteen months earlier, she was hospitalized with similar symptoms and diagnosed with presumed viral pneumonitis; she was discharged on supplemental oxygen for persistent hypoxia, but she continued to experience a daily cough, which she attributed to asthma. On this admission, she was found to be hypoxic (SpO2 88% on RA), tachypneic, with diffuse fine crackles on lung exam. Chest computed tomography showed progression of bilateral interstitial infiltrates compared to prior imaging. Autoimmune screening, viral and fungal serologies were unremarkable. Bronchoscopy revealed diffuse erythema without focal bleeding, and bronchoalveolar lavage was negative for infectious pathogens and malignancy. Due to the clinical deterioration, she was admitted to the intensive care unit and intubated. An open-lung biopsy revealed numerous lipid-laden macrophages, multinucleated foreign-body giant cells, and mild interstitial chronic inflammation with fibrosis. Special stains were negative for acid-fast bacilli and fungi, ruling out TB and fungal infections. She denied exposure to oil-based substances. Chronic GERD-related microaspiration was considered the likely etiology in this case. Subsequently, patient was treated with intravenous antibiotics, corticosteroids, and proton pump inhibitors. She improved significantly, was successfully extubated, and continued to recover with optimized reflux management and supportive pulmonary care. Discussion: GERD-related microaspiration is an overlooked etiology of exogenous lipoid pneumonia. Repeated inhalation of gastric contents containing lipids leads to accumulation of lipid-laden macrophages in the lungs, triggering inflammation and fibrosis. Unlike classic lipoid pneumonia from oil ingestion, GERD-associated cases develop gradually and silently. Early diagnosis and treatment, including acid suppression and steroids, can improve outcomes and prevent lung damage.