Definition/General
Introduction:
Viral meningitis is aseptic inflammation of meninges caused by viruses
Most common cause of aseptic meningitis
Common viruses: Enterovirus, HSV, VZV
Self-limiting in most cases
Better prognosis than bacterial.
Origin:
Direct viral invasion of meninges
Post-infectious immune response
Reactivation of latent viruses (HSV, VZV).
Classification:
Based on virus: Enteroviral (70%)
Herpetic (HSV-1, HSV-2)
Varicella-zoster
Epstein-Barr virus
COVID-19 related.
Epidemiology:
Most common in summer months
Children and young adults
Enterovirus most common overall
Good prognosis (mortality <1%).
Clinical Features
Presentation:
Acute onset headache and fever
Neck stiffness
Photophobia
Viral prodrome
No focal neurological signs.
Symptoms:
Headache (95% cases)
Fever (90% cases)
Neck stiffness (80% cases)
Photophobia (70% cases)
Nausea/vomiting (60% cases).
Risk Factors:
Young age
Summer season
Recent viral illness
Immunocompromised state.
Screening:
Lumbar puncture
Viral PCR
Serology
CT brain (if focal signs).
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Microscopic Description
Histological Features:
Lymphocytic pleocytosis (50-500 cells/μL)
Predominantly lymphocytes (>80%)
Early neutrophilic phase (first 24 hours)
Clear background
No bacteria.
Cellular Characteristics:
Small mature lymphocytes
Large activated lymphocytes
Occasional plasma cells
Reactive changes.
Architectural Patterns:
Dispersed lymphocytes
No clustering
Clean background
No granulomas.
Grading Criteria:
Normal/mildly elevated protein (<100 mg/dL)
Normal glucose (>50% serum)
Normal ADA
Viral PCR positive.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
CSF, volume [X] mL, clear, colorless
Cell Count
Total cell count: [X] cells/μL (50-500 cells/μL)
Cell Differential
Lymphocytes: [X]% (>80%), Neutrophils: [X]%, Monocytes: [X]%
Biochemistry
Protein: [X] mg/dL (<100), Glucose: [X] mg/dL (normal)
Viral Studies
Viral PCR: [Results if available]
Final Diagnosis
CSF findings consistent with viral meningitis (aseptic meningitis)