| Progressive increase in bloody fluid return with sequential lavages/hemosiderin positive alveolar macrophage °˙ diffuse alveolar hemorrhage |
| Milky fluid with positive periodic Acid-Schiff staining and amorphous acellular debris °˙ pulmonary alveolar proteinosis |
| Malignant cells per light microscopy or flow cytometry °˙ cancer |
| Lymphocytosis (>25%) °˙ granulomatous diseases: sarcoidosis, hypersensitivity pneumonitis, or chronic beryllium disease |
| Neutrophilia (>50%) °˙ acute lung injury, aspiration pneumonia, or suppurative infection |
| Eosinophilia (>25%) °˙ virtually diagnostic of acute or chronic eosinophilic pneumonia |
| A cell differential count of >1% mast cells, >50% lymphocytes, and >3% neutrophils °˙ acute hypersensitivity pneumonitis |
| A predominance of macrophages containing smoking-related inclusions with no or minor increases in other cell types °˙ smoking-related ILDs (DIP, RBILD, or PLCH) |
| CD4/CD8 >4 °˙ sarcoidosis |
| CD1a positive cells ≥5%/Birbeck granules in macrophages (electron microscopy) °˙ Langerhans’ cell histiocytosis |
| Positive lymphocyte transformation test to specific beryllium antigen °˙ chronic beryllium disease |
| Ferruginous bodies °˙ asbestosis |
| Dust particles by polarized microscope °˙ silicosis |
| Lipid-laden macrophages (oil-red-O-stain) °˙ lipoid pneumonia/chronic microaspiration |
