- RA-associated interstitial lung disease (RA-ILD).
- Pleural disease (pleural thickening/effusions).
- Airway disease (Both upper & lower airway).
- Rheumatoid nodules
- Drug-induced lung toxicity (i.e., Methotrexate-induced lung injury)
- Fibro-bullous disease
- Thoracic cage immobility
- Venous thromboembolic disease
- Vasculitis
- Pneumonia.
RHEUMATOID EFFUSION:
- WCC <5000/mm3
- Fluid glucose <60 mg/Dl
- Pleural fluid to serum glucose ratio < 0.5
- pH < 7.3
- High pleural LDH level (ie, > 700 IU/L)
- Cytology: Slender or elongated multinucleated macrophages, round giant multinucleated macrophages, and necrotic background debris.
Pulmonary function testing in ILD (PFT):
- Reduced VC, lung volumes, & DLCO.
- Oxygen desaturation during exercise.
- Restrictive abnormalities common (poor muscle strength or kyphosis due to osteoporosis rather than ILD).
