Dyspnea and Deception: Overcoming Diagnostic Hurdles in Pulmonary Alveolar Proteinosis.

Pulmonary alveolar proteinosis (PAP) is a rare pulmonary disorder characterized by abnormal surfactant accumulation due to defective alveolar macrophage clearance. It often presents with exertional dyspnea and nonspecific imaging findings, commonly leading to diagnostic delays. We present the case of a 56-year-old woman with progressive hypoxia initially misattributed to acute respiratory distress syndrome, noncardiogenic pulmonary edema, and hypersensitivity pneumonitis. Corticosteroids were initiated based on early differential considerations. Further evaluation revealed concurrent methicillin-resistant Staphylococcus aureus (MRSA) pneumonia and bronchoalveolar lavage findings suggestive of PAP. Following stabilization and treatment of the infection, transbronchial biopsy confirmed PAP. The patient required prolonged intensive care and was ultimately transferred for whole-lung lavage. This case highlights the critical importance of early recognition of PAP in patients with characteristic imaging findings and progressive respiratory failure. Misdiagnosis can lead to inappropriate therapies and increased risk of infectious complications.