Abstract: Objective  To study the diagnostic and prognostic value of cerebrospinal fluid (CSF) cytology in tuberculous meningitis.
Methods  CSF cells were collected with FMU-5 were evaluated with optical microscope after May-Grunwald-Giemsa(MGG) staining.
Results  In 91.38% (700/766) of patients with tuberculous meningitis, CSF cytology demonstrated a mixed cell profile, and in 8.62% (66/766) a lymphoid cell profile was shown, whereas neutrophils in purulent meningitis and lymphocytes in viral meningitis predominated. Large lymphoid cells were seen in 97.52% (747/766) of tuberculous meningitis, but rarely seen in purulent meningitis or viral meningitis. The number of neutrophils and large lymphoid cells gradually decreased with the improvement of tuberculous meningitis; persisted existence of neutrophils and large lymphoid cells predicted a poor prognosis.
Conclusion  CSF cytology of tuberculous meningitis is a mixed cell and lymphoid cell profile. Large lymphoid cells are characteristic features of tuberculous meningitis; dynamic changes in CSF cytology can be used for differentiating different types of meningitis and for evaluating the prognosis.

Key words: Tuberculosis,meningeal/cerebrospinal fluid, Cerebrospinal fluid/cytology