A 42-year-old woman presents with progressive breathlessness and dry cough. HRCT shows bilateral ground-glass opacities with subpleural sparing, crazy paving pattern, and cysts. BAL shows lymphocytosis >25%. She is found to have anti-GM-CSF antibodies. What is the diagnosis?
- A Hypersensitivity pneumonitis (HP)
- B Pulmonary alveolar proteinosis (PAP) ✓
- C Non-specific interstitial pneumonia (NSIP)
- D Lymphoid interstitial pneumonia (LIP)
Correct answer: B. Pulmonary alveolar proteinosis (PAP)
Explanation
Pulmonary alveolar proteinosis (PAP) is characterized by accumulation of periodic acid-Schiff (PAS)-positive lipoproteinaceous material in alveoli due to impaired macrophage GM-CSF signaling. Autoimmune PAP is caused by anti-GM-CSF (anti-granulocyte-macrophage colony-stimulating factor) antibodies. HRCT shows crazy paving pattern (ground-glass + septal thickening) with geographic distribution and subpleural sparing. BAL fluid appears milky and shows acellular PAS+ material. Treatment is whole-lung lavage and subcutaneous GM-CSF injections.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.