PET scan response before and after blinatumomab treatment. (A) PET scan on day +92 showing concern for PTLD with multifocal, fluorodeoxyglucose-avid uptake and lymphadenopathy in the abdomen and pelvis. (B) PET scan on day +179 showing significant metabolic and structural improvement of abdominal and pelvic lesions 1 day after completion of blinatumomab. PET, positron emission technology; PTLD, posttransplant lymphoproliferative disease.