A 55-year-old man with a 10-year history of RA on methotrexate 20 mg/week develops progressive dyspnea. HRCT chest shows bilateral basilar reticulation with honeycombing and traction bronchiectasis. Pulmonary function tests show FVC 58% predicted, DLCO 45% predicted. The most likely diagnosis is:
- A Methotrexate-induced hypersensitivity pneumonitis
- B Rheumatoid pleuritis
- C RA-associated usual interstitial pneumonia (UIP) ✓
- D Obliterative bronchiolitis
Correct answer: C. RA-associated usual interstitial pneumonia (UIP)
Explanation
Honeycombing with basal predominance and traction bronchiectasis is the radiological pattern of usual interstitial pneumonia (UIP), the most common and most severe ILD pattern associated with RA. RA-UIP carries a prognosis similar to idiopathic pulmonary fibrosis. Methotrexate pneumonitis presents acutely/subacutely with ground-glass opacities, fever, and eosinophilia, not honeycombing. Obliterative bronchiolitis shows air trapping and decreased attenuation on expiratory CT.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.