pleocitose

Pleocytosis is an abnormal increase in the number of cells in body fluids, most commonly in the cerebrospinal fluid (CSF). In adults, normal CSF contains about 0–5 white blood cells per microliter, and pleocytosis is diagnosed when the count exceeds this range. The term pleocytose is a variant spelling used in some languages; pleocytosis is the standard English term.

The pattern of the cellular predominance in CSF helps suggest possible causes. Neutrophilic pleocytosis is typical of acute bacterial meningitis or chemical meningitis; lymphocytic pleocytosis is more common with viral meningitis, tuberculous meningitis, fungal meningitis, and some autoimmune conditions. Eosinophilic pleocytosis points to parasitic infections, certain drug reactions, or responses to intrathecal devices.

Pleocytosis is usually accompanied by other CSF chemistry changes. Elevated CSF protein is common, while glucose may be normal in viral infections and reduced in bacterial, tuberculous, or fungal meningitis. The overall CSF profile, along with clinical presentation and imaging, guides diagnostic consideration. Causes include infectious meningitis (bacterial, viral, tuberculous, fungal, parasitic), inflammatory or autoimmune CNS diseases (such as multiple sclerosis or neurosarcoidosis), malignancy with leptomeningeal involvement, and noninfectious processes like hemorrhage-related inflammation or drug-induced meningitis. Pleocytosis may also be observed in inflammatory conditions of other fluids, though CSF pleocytosis is the most clinically relevant in neurology.

Diagnosis relies on lumbar puncture with CSF analysis—cell count with differential, protein, glucose, Gram stain, cultures, and pathogen-specific PCR or antigen tests—along with clinical correlation. Management is directed at the underlying cause rather than the pleocytosis itself.