Smudge cells due to infectious mononucleosis

Area of Science:

• Hematology
• Virology
• Clinical Pathology

Background:

• Smudge cells are established prognostic indicators in chronic lymphocytic leukemia.
• These abnormal cells can also be observed in various viral infections.
• Automated hematology analyzers may misinterpret smudge cells.

Purpose of the Study:

• To report a unique case of infectious mononucleosis presenting with abnormal hyperleukocytosis.
• To describe the presence and potential misinterpretation of smudge cells in this context.
• To emphasize the importance of manual peripheral blood smear review.

Main Methods:

• Case report of a patient with infectious mononucleosis.
• Analysis of peripheral blood smears.
• Review of automated blood count data.

Main Results:

• The patient exhibited marked hyperleukocytosis (WBC 41,600/mm3).
• Smudge cells were identified in peripheral blood smears.
• Automated blood count erroneously identified smudge cells as normal lymphocytes.

Conclusions:

• Smudge cells can be present in infectious mononucleosis, mimicking findings seen in hematologic malignancies.
• Manual review of peripheral blood smears is crucial for accurate diagnosis, especially in cases of hyperleukocytosis.
• This case underscores the limitations of automated cell counting in specific clinical scenarios.