Fatal interstitial pneumonitis in a patient with relapsed diffuse large B cell lymphoma following yttrium-90 ibritumomab tiuxetan

Summary There is no previous report of fatal interstitial pneumonitis related to the administration of yttirum-90 ibritumomab tiuxetan. We report first case of fatal interstitial pneumonitis in a 35-year-old female patient with relapsed diffuse large B cell lymphoma following yttrium-90 ibritumomab tiuxetan. A pathological evaluation through a surgical lung biopsy demonstrated a “interstitial pneumonitis” pattern. Although high-dose methylprednisolone was administered, she died due to acute respiratory distress syndrome, secondary to radioimmunotherapy-induced interstitial pneumonitis. In this report, we discuss the etiology, diagnosis, and management of radioimmunotherapy-induced interstitial pneumonitis.