Virus

Mononucleosis-Like Syndrome

search

Mononucleosis-Like Syndrome, Mononucleosis Differential Diagnosis, Mononucleosis Diagnostic Approach

  1. Step 1: Monospot Test (heterophile Antibody) Positive
    1. Diagnose Epstein-Barr Virus
  2. Step 2: Complete Blood Count with differential
    1. Evaluate for >10% Atypical lymphocytes
    2. Lymphocytosis >50% and Atypical lymphocytes >10% may be sufficient alone to diagnose Mononucleosis without further testing
      1. Test Sensitivity: 75%
      2. Test Specificity: 92%
  3. Step 3a: Absolute Lymphocyte Count <4000/mm3
    1. Consider alternative diagnoses
      1. Consider HIV Test if <10% Atypical lymphocyte
      2. See Acute Retroviral Syndrome for testing
  4. Step 3b: Absolute Lymphocyte Count >4000/mm3 and >10% Atypical lymphocytes
    1. Consider Viral Capsid Antigen (VCA) IgM (replaces EBV IgM)
      1. VCA IgM positive: Diagnose Epstein-Barr Virus
    2. Consider EBV IgM (if VCA IgM not available)
      1. EBV IgM Positive: Diagnose Epstein-Barr Virus
      2. EBV IgM Negative: Go to Step 4
  5. Step 4: Obtain CMV IgM
    1. CMV IgM Positive: Diagnose CMV-Induced Mononucleosis
    2. CMV IgM Negative: Evaluate for differential diagnosis
      1. Toxoplasmosis
      2. Acute Viral Hepatitis
      3. Human Herpesvirus 6