Abstract
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.
Keywords: Smudge cell, Infectious mononucleosis, Hyperleukocytosis
A 5-year-old boy with a 6 day history of fever and bilateral cervical lymphadenopathy was referred to our hospital. Physical examination revealed lymph node swelling of up to 1.5 cm on both sides of the neck, exudative tonsillitis, but no hepatomegaly or splenomegaly. Blood tests showed leukocytes 41,600/μL (lymphocyte: 67 %, atypical lymphocyte: 20 %). The peripheral blood smears were confirmed under a microscope, and about half of the white blood cells were smudge cells (Fig. 1). Epstein-Barr virus (EBV) virus capsid antigen-IgM was detected (1.6 index, BML, tokyo) and EBV nuclear antigen was not detected. Blood EBV-PCR showed 51,987 copies/mL. The next day he was hospitalized for sleep apnea due to upper airway obstruction. He administered dexamethasone 1 mg/kg/day and was discharged because his airway obstruction symptoms improved. A blood test two weeks after discharge from the hospital revealed that the white blood cells were 7510/μL (lymphocyte: 69 %, atypical lymphocyte: 0%), which was within the standard value, and there were only a few smudge cells.
Fig. 1.
Smudge cells (allow) were found in about the same number as normal white blood cells (May-Giemsa staining staining, X400 magnification).
The Smudge cells reflect the fragility of lymphocytes, which appear to be flattened or smudged in the process of being spread on the glass slide. There are well studied as a prognostic factor for chronic lymphocytic leukemia [1], but it is also found in viral infections [2]. Previous study revealed that the smudge cells were observed in IM with high specificity (96.1 %) [3]. Because IM is more common in children than chronic lymphocytic leukemia, the picture of smudge cells may provide pediatricians with an information as one of the findings suspecting IM. 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.
Formatting of funding sources
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
References
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