CSF cytology of acute viral meningitis and meningoencephalitis.

The CSF of 12 patients with acute meningitis and meningoencephalitis of viral nature (proven in 10 and probably in 2) was investigated by light microscopy. In early CSF, 1--31% reactive lymphocytes and 1--6% plasma cells were found consistently. In addition, various lymphoid cell features of marked immune activation were disclosed in association: cell polymorphism, normal-appearing mitosis and binucleation, abnormal nuclear lobulation and even partition, as well as Russell bodies, morular appearance and clasmatosis in plasma cells. The CSF findings are discussed with respect to those described in tuberculous meningitis and multiple sclerosis and distinguishing features are suggested to occur in early CSF of viral meningitis.