Abstract Introduction Pulmonary alveolar proteinosis (PAP) is a rare disorder characterized by accumulation of surfactant material within alveoli due to impaired clearance by alveolar macrophages. The material is periodic acid-Schiff (PAS)-positive, composed of phospholipids and apoproteins, with minimal inflammation and preserved lung architecture. Clinically, patients present with progressive dyspnea, cough, and hypoxemia. Imaging often reveals bilateral ground-glass opacities (GGOs) with interlobular septal thickening, creating a “crazy-paving” pattern. PAP may be autoimmune, secondary, or congenital. Autoimmune PAP, mediated by anti-GM-CSF antibodies, accounts for most cases, whereas secondary PAP is associated with hematologic malignancies, infections, or occupational exposures. Whole-lung lavage (WLL) remains the mainstay of treatment. Case Presentation A 48-year-old man with hypertension and remote sleeve gastrectomy presented with fever, cough, and dyspnea. Chest imaging showed bilateral GGOs consistent with multifocal pneumonia, and he was treated with levofloxacin and corticosteroids. Despite therapy, he remained hypoxemic and required home oxygen. Repeat CT revealed worsening GGOs with a crazy-paving pattern. Infectious and autoimmune evaluations were negative except for a positive ANA. Bronchoscopy with BAL was nondiagnostic, while repeat BAL and transbronchial biopsy showed alveoli filled with PAS-positive material, diagnostic of PAP. Anti-GM-CSF antibody was negative, suggesting secondary PAP. Hematologic evaluation excluded malignancy, but occupational history revealed long-term HVAC exposure with dust inhalation. Discussion The patient underwent staged bilateral WLL, producing milky effluent and marked improvement in symptoms, imaging, and oxygenation. Pre-treatment pulmonary function testing demonstrated a restrictive defect (FVC 3.41 L, 63% predicted) and severely reduced diffusion capacity (DLCO 10.93 mL/min/mmHg, 34.9% predicted). Post-lavage, FVC improved to 4.32 L (80.7% predicted) and DLCO to 22.87 (73.4% predicted), with oxygen saturation of 98% on room air. This case highlights the diagnostic challenge of PAP, which can mimic pneumonia and delay definitive treatment. Recognition of the “crazy-paving” pattern in the appropriate context should prompt consideration of PAP. Conclusion This case underscores the importance of distinguishing autoimmune from secondary PAP, as management differs. In secondary PAP, exposure elimination and WLL remain essential. Clinicians should maintain vigilance for opportunistic infections and hematologic disorders. Whole-lung lavage remains the most effective therapy, resulting in significant clinical, physiological, and radiographic improvement. This abstract is funded by: None
Chandramohan et al. (Fri,) studied this question.