A 77-year-old woman with Burkitt leukemia and lymphomatous meningitis was started on the PETHEMA (Programa para el Estudio de la Terapéutica en Hemopatía Maligna) protocol of chemotherapy. After the first chemotherapy cycle, the patient's leukocyte count in the cerebrospinal fluid (CSF) was 0. On cycle 2, the patient received intrathecal liposomal cytarabine (Depocyte®). Two weeks later, there was a discrepancy in the laboratory results. The leukocyte count obtained for unstained CSF with a hemocytometer was 540/μL (540 × 106/L), whereas flow cytometry and Wright–Giemsa staining revealed an absence of leukocytes. A photomicrograph of the CSF is shown in Fig. 1.

CSF sample
Fig. 1. CSF sample from a patient with lymphomatous meningitis treated with Depocyte.

  1. What is the correct CSF leukocyte count? 
  2.  Is the microscopical appearance of the structures seen in Fig. 1 typical for leukocytes? 
  3. Can Depocyte interfere with a CSF examination 15 days after its administration? 
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