Piritrexim-induced pulmonary toxicity.

We describe a patient with transitional cell carcinoma of the renal pelvis who developed respiratory dysfunction and an abnormal chest x-ray with diffuse interstitial opacities while on chemotherapy with piritrexim, a methotrexate analog. Drug discontinuation resulted in complete resolution of the clinical and radiographic picture. The pulmonary toxicity is probably induced by piritrexim.