Definition/General
Introduction:
Tuberculous meningitis is chronic infection of meninges by M
tuberculosis
Most severe form of extrapulmonary TB
High morbidity and mortality
More common in children and immunocompromised
Subacute onset characteristic.
Origin:
Results from hematogenous spread
Rich focus rupture into subarachnoid space
Direct extension from brain tuberculoma.
Classification:
Stages: Stage I (prodromal)
Stage II (meningeal irritation)
Stage III (coma, focal deficits).
Epidemiology:
High prevalence in developing countries
Children <5 years most affected
HIV co-infection increases risk
Mortality 15-40%.
Clinical Features
Presentation:
Subacute onset (weeks)
Fever and headache
Neck stiffness
Altered consciousness
Cranial nerve palsies
Hydrocephalus.
Symptoms:
Fever (90% cases)
Headache (85% cases)
Neck stiffness (80% cases)
Vomiting (70% cases)
Altered consciousness (60% cases).
Risk Factors:
HIV infection
Young age
Malnutrition
Immunosuppression
Contact with TB patient.
Screening:
CT/MRI brain
Chest X-ray
Tuberculin skin test
Lumbar puncture.
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Microscopic Description
Histological Features:
Lymphocytic pleocytosis (100-500 cells/μL)
Predominantly lymphocytes (60-90%)
Neutrophils early in disease
AFB rarely seen (<20%)
Epithelioid cells occasionally.
Cellular Characteristics:
Small mature lymphocytes
Large activated lymphocytes
Plasma cells
Neutrophils (early stage)
Epithelioid cells (pathognomonic).
Architectural Patterns:
Dispersed lymphocytes
Epithelioid clusters
Granulomatous pattern
Fibrin web formation.
Grading Criteria:
High protein (100-500 mg/dL)
Low glucose (<40 mg/dL)
High ADA (>10 U/L)
PCR positivity.
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 to slightly turbid
Cell Count
Total cell count: [X] cells/μL (100-500 cells/μL)
Cell Differential
Lymphocytes: [X]% (60-90%), Neutrophils: [X]%, Monocytes: [X]%
Biochemistry
Protein: [X] mg/dL (100-500), Glucose: [X] mg/dL (<40), ADA: [X] U/L (>10)
AFB Staining
AFB staining: [Positive/Negative]
Final Diagnosis
CSF findings consistent with tuberculous meningitis