PMNs in normal spinal fluid examined by the cytocentrifuge technique.

The presence in unconcentrated CSF specimens of even a single polymorphonuclear (PMN) cell has been regarded as diagnostic of central nervous system (CNS) disease. In 18 of 50 consecutive cytocentrifuged specimens obtained from patients without evidence of CNS disease, however, we found 1 to 6 PMN cells. The observation of occasional PMN cells in concentrated CSF specimens does not appear to be diagnostic of a CNS abnormality.