Pneumonitis complicating methotrexate therapy for pustular psoriasis

We report a patient with pustular psoriasis who developed interstitial pneumonitis after receiving weekly methotrexate (MTX) therapy at an average dose of 20 mg for 26 years. The patient responded dramatically to withdrawal of the drug and administration of corticosteroids. Pulmonary toxicity is a rare adverse effect of MTX therapy and is particularly uncommon in psoriatics. As interstitial pneumonitis is a potentially fatal but reversible complication, early respiratory symptoms even in patients on low-dose MTX treatment should be appropriately investigated.