Methotrexate-associated pneumonitis: usefulness of lung ultrasound.

Methotrexate-associated pneumonitis is an idiosyncratic hypersensitivity reaction with a low incidence and is independent of the development of rheumatoid arthritis-associated interstitial lung disease. Early discontinuation of methotrexate and corticosteroid therapy are key to management, and prognosis is generally favorable. This case highlights the potential role of lung ultrasound as a rapid bedside tool for detection and monitoring of MTX-Pneu.