Uncommon cells in cerebrospinal fluid in Japanese encephalitis: A case report.

RATIONALE: Cerebrospinal fluid (CSF) cytomorphology plays a critical role in the diagnosis of central nervous system infections. During an outbreak of Japanese encephalitis (JE) in Ningxia, China, an uncommon CSF cytomorphology in 1 case posed diagnostic challenges, highlighting the need to correlate cellular findings with clinical context for accurate interpretation.

PATIENT CONCERNS: A 56-year-old female farmer from a JE-endemic village presented with fever, headache, dizziness, and nausea. Initial CSF cytological analysis revealed 2 uncommon cell types: type I cells, resembling siderophages, and type II cells mimicking malignant tumor cells.

DIAGNOSES: JE was confirmed through JE virus-specific immunoglobulin G antibodies in both serum and CSF and genotype Ib identification. No evidence of cerebral hemorrhage or neoplastic meningitis was found. These 2 cell types disappeared during subsequent follow-up examinations.

INTERVENTIONS: Intravenous ganciclovir (300 mg, Q12H) was initiated promptly.

OUTCOMES: Symptoms resolved within 1 week. At the 1-month follow-up, the patient recovered completely, confirming the JE diagnosis.

LESSONS: Transient uncommon CSF cells in this case of JE may exhibit morphological features resembling siderophages or malignant tumor cells, thus requiring a comprehensive correlation between cytomorphological findings and both clinical and laboratory data. This case highlights CSF cytology's diagnostic value in central nervous system infections while cautioning against overreliance on isolated cellular findings. Effective collaboration between clinicians and cytologists is essential to prevent misdiagnosis and ensure appropriate therapeutic guidance.