9. Brain Biopsy - Additional Histopathology Results

Brain Biopsy - Additional Histopathology Results

• HSV-1,2 immunohistochemistry was positive
  • initially mostly nuclear staining in neurons
  • after nuclear membrane ruptures, cytoplasmic staining is noted
  • mostly macrophages, foamy cytoplasm
    
• HSV Direct Immunoflourescence Test also Positive

Reagent characteristics for immunohistochemistry

• cocktail of polyclonal rabbit anti-HSV-1 and anti-HSV-2 (Dako)
  
• purchased separately and mixed together in the Immunology lab
  
• immunogen is detergent-solubilized infected whole rabbit cornea cells
  
• both polyclonals react with type-specific and common antigens
  • all major glycoproteins in envelope and at least one core protein
    
• some cross-reactivity with VZV at high concentrations
  
• no cross reactivity with CMV or EBV

Reagent characteristics for DFA

• SimulFluor HSV/VZV immunofluorescence assay (Light Diagnostics)
  
• single reagent to detect HSV and VZV
  
• monoclonal antibodies specific for HSV-1 and HSV-2
  • bind to 155 kd major capsid protein in HSV-infected cells
    
• monoclonal antibodies specific for VZV
  • bind to glycoprotein gp I and immediate early antigen of VZV
    
• illuminate with UV light - fluorescence microscopy - FITC filter
  • HSV antigen-antibody complex apple-green
  • VZV antigen-antibody complex yellow-gold

• Is HSV DNA PCR necessary?
  Diagnosis provided by DFA and culture methods. PCR assay not necessary.
  
• Should we send out Viral Referral Tests, e.g. West Nile PCR and ARBO Culture?
  Diagnosis obtained by HSV DFA and immunohistochem. Arbovirus culture
  and W. Nile PCR not required at this time. Specimen was frozen at -70oC for future studies.
  

Final Diagnosis: Viral Encephalitis due to HSV-1

REVIEW

• gross pathology
  
• histopathology
  
• laboratory evaluation