Methotrexate-induced pulmonary injury: serial CT findings

We describe serial computed tomographic (CT) findings of methotrexate (MTX)-induced pulmonary injury.

The cases of 8 patients (3 men and 5 women; mean age 58.6 years, range 16 to 75 years) of clinically diagnosed MTX-induced pulmonary injury were reviewed. Six patients had rheumatoid arthritis, 1 had lupus erythematosus profundus, and 1 had juvenile rheumatoid arthritis. CT findings on admission and at follow-up were evaluated.

The most common CT features were diffuse and patchy bilateral ground-glass opacity with (n = 3) or without reticulation (n = 4) and consolidation (n = 1). These opacities showed no predilection for any particular lung zone in 6 patients but did show dependent predilection in 1 patient and upper lobe predilection in 1. Diffuse centrilobular ill-defined nodules were noted in 1 patient, which disappeared on follow-up. During the average post-treatment follow-up period of 31.0 days (range 3 to 76 days), the opacities quickly improved after treatment in 6 patients; however, in 2 patients with pre-existing interstitial pneumonitis the opacities were refractory.

CT features of MTX-induced pulmonary injury were variable and included diffuse parenchymal opacification, reticular opacities, and centrilobular nodules. These opacities usually responded quickly to treatment; however, those patients with lung fibrosis at presentation may have worse prognosis.