Infectious mononucleosis complicated by haemolytic anaemia due to the Donath Landsteiner antibody and by severe neutropenia.

A young man developed infectious mononucleosis complicated by profound anaemia due to haemolysis. The Donath Landsteiner antibody was found in his serum. He was treated successfully by blood transfusion but subsequently developed severe neutropenia. Both complications have been reported previously but not in the same individual. No underlying immune deficiency could be identified.