Smudge cells due to infectious mononucleosis

The smudge cells are well studied as a prognostic factor for chronic lymphocytic leukemia, but it is also found in viral infections. We experienced a case of abnormal hyperleukocytosis (WBC 41,600/mm3) associated with infectious mononucleosis (IM). The smudge cells were observed in peripheral blood smears, and were counted by mistake for the normal lymphocytes by the automatic blood count meter