APIMC243889244 - CME/CMLE - Body Fluid Microscopy #2: Normal Cerebrospinal Fluid-APIMC243889244

APIMC243889244 - Educational Activity

Pdf Summary

This educational commentary, presented by Dr. Padmini A. Manrai, provides an overview of normal cerebrospinal fluid (CSF) characteristics and its clinical significance in diagnosing central nervous system infections, particularly meningitis. CSF is a plasma ultrafiltrate produced by the choroid plexus, typically clear, colorless, and acellular, with up to five white blood cells (predominantly lymphocytes) and five red blood cells per high power field considered normal.<br /><br />A case of a 19-year-old female with fever, headache, and fatigue undergoing lumbar puncture illustrates the diagnostic role of CSF analysis. Normal CSF cytology includes lymphocytes (7–10 µm, large hyperchromatic nucleus with scant cytoplasm), segmented neutrophils (10–18 µm, multilobed nucleus, cytoplasmic granules), monocytes/macrophages (16–22 µm, variable morphology including vacuolation), and red blood cells (6–8 µm, anucleate discoid shape with central pallor). Reactive monocytes/macrophages may increase during infections, indicating an immune response.<br /><br />CSF analysis integrates gross examination (e.g., clarity), cell counts/differentials, and biochemical parameters such as protein and glucose levels. Infectious etiologies show distinct patterns: bacterial or tuberculosis meningitis typically presents with turbid CSF, elevated white blood cells (especially neutrophils), increased red blood cells and protein; viral and fungal meningitis usually maintain clear CSF with lymphocytic predominance and low protein.<br /><br />Monocyte elevation suggests reactive or chronic inflammatory processes. Bacterial meningitis demands further testing like Gram stain for pathogen identification. Non-infectious causes (e.g., subarachnoid hemorrhage, multiple sclerosis, Guillain-Barre syndrome, metastatic cancer) require additional clinical and radiologic correlation.<br /><br />In sum, CSF cytology and biochemical analysis are vital for differentiating meningitis etiologies and guiding patient management. The commentary underscores the importance of recognizing normal and reactive cell morphologies for accurate diagnosis and treatment planning.

Keywords

cerebrospinal fluid

CSF analysis

meningitis diagnosis

central nervous system infections

lumbar puncture

CSF cytology

white blood cells

bacterial meningitis

viral meningitis

reactive monocytes