The Remarkable Journey of a Low-Frequency Alloantibody.

Herein we describe a case of febrile non-hemolytic reaction (FNHTR) in a 64-year-old male 20 min after the transfusion of one red blood cell unit. 20 days prior the patient had undergone an allogeneic hematopoietic stem cell transplantation (HCT) from an unrelated donor with minor ABO disparity. The patient had been treated for plasma cell myeloma with multiple transfusions in the past, but no transfusion reactions or alloimmunization had been reported.