Atypical lymphoid cells in cerebrospinal fluid in acute Epstein Barr virus infection: A case report demonstrating a pitfall in cerebrospinal fluid cytology

Background Cytologic examination of cerebrospinal fluid (CSF) continues to be important in the diagnosis of maligmancies involving the leptomeninges. A well-recognized pitfall is over interpretation of the presence of atypical lymphocytes that resemble malignant lymphoid cells in the CSF. A definite diagnosis is often difficult because of limited viability of cells and small sample size of CSF. Case A 25-year-old patient with a past history of treated large granular lymphocytic leukemia and presence of a predominant population of large, atypical lymphoid cells in the CSF, giving us the impression of involvement with large cell lymphoma. However, a timely call to the hematologist revealed that the serology was positive for acute Epstein-Barr virus infection. Flow cytometry of CSF confirmed polyclonal population of B-cells and T-cells. Conclusion The presence of atypical cells in the CSF certainly warrants a detailed look at the patient's laboratory investigations and communication with the hematologist, because it may be the only specimen available for diagnosis on which therapy and prognosis is based.