✅ Model Answer:
• Diagnosis: Infectious mononucleosis (EBV) — fever for 2 weeks, sore throat, fatigue, generalized lymphadenopathy, splenomegaly, atypical lymphocytes (20%), elevated transaminases, positive Monospot. EBV VCA IgM would confirm acute infection.
• Any other test: Monospot (Heterophile), EBV serologies (VCA IgM, VCA IgG, EBNA) to confirm acute infection (if Monospot negative), CBC with differential, liver function tests, abdominal ultrasound (spleen size), throat culture (rule out GAS if pharyngitis).
• What to do next: Supportive care (rest, hydration, analgesia). Avoid contact sports (splenic rupture risk) for 4-6 weeks. Avoid amoxicillin/ampicillin (rash risk).
• Follow-up plan: Monitor for complications: splenic rupture, airway obstruction, hepatitis, encephalitis. If splenomegaly persists, extend activity restrictions. Fatigue may persist weeks-months. CBC and LFTs should normalize.

✅ Model Answer:
• Infectious mononucleosis (mono) is an acute viral illness caused by the Epstein-Barr virus (EBV), a member of the herpesvirus family.
• Transmission: Primarily through saliva ("kissing disease"), but can also be transmitted through blood, sexual contact, and organ transplantation.
• Incubation period: 4-6 weeks.
• Clinical features (classic triad):
- Fever (usually 38-39°C, may last 1-3 weeks)
- Pharyngitis (exudative or non-exudative, severe sore throat)
- Lymphadenopathy (cervical, generalized, posterior cervical nodes common)
- Splenomegaly (in 50-60% of cases)
- Fatigue (can persist for weeks to months)
- Hepatitis (elevated transaminases, jaundice less common)
- Rash (especially with amoxicillin/ampicillin)

✅ Model Answer:
• Complete blood count (CBC):
- WBC: Leukocytosis (10,000-20,000/µL), lymphocytosis (≥50%)
- Atypical lymphocytes: >10-20% (activated T-cells, "Downey cells") — hallmark of EBV
- Platelets: May be low (mild thrombocytopenia)
- Hemoglobin: Usually normal (mild anemia possible)
• Liver function tests:
- AST/ALT: Mild to moderate elevation (2-3x normal)
- Alkaline phosphatase: May be elevated
- Bilirubin: Usually normal or mildly elevated
• Serology:
- Monospot (heterophile antibody): Positive in 80-90% of adolescents; may be negative in children <4 years
- EBV VCA IgM: Positive in acute infection (most specific)
- EBV VCA IgG: Indicates past infection
- EBNA IgG: Positive later in infection (indicates recovery)

✅ Model Answer:
• Amoxicillin/ampicillin rash: Up to 70-90% of patients with EBV develop a maculopapular rash after taking amoxicillin or ampicillin.
• Why? The exact mechanism is unknown but believed to be due to a non-allergic immune response (not a true penicillin allergy).
• Clinical significance:
- The rash typically appears 5-10 days after starting the antibiotic.
- It is usually self-limiting and resolves after stopping the antibiotic.
- Important: It is NOT a true allergy; patients may tolerate penicillins later in life.
- However, it is often mislabeled as a penicillin allergy.
• Clinical pearl: Avoid amoxicillin/ampicillin in patients with suspected EBV unless there is a clear bacterial indication (e.g., streptococcal pharyngitis confirmed by culture).

✅ Model Answer:
• Complications:
- Splenic rupture: Most feared complication — can occur spontaneously or with minor trauma (contact sports). Risk is highest in first 3 weeks.
- Airway obstruction: Due to severe pharyngeal edema and tonsillar hypertrophy
- Hepatitis: Transaminitis, jaundice, rarely fulminant hepatitis
- Hematologic: Hemolytic anemia, thrombocytopenia, aplastic anemia (rare)
- Neurologic: Encephalitis, meningitis, Guillain-Barré syndrome, Bell's palsy, transverse myelitis
- Cardiac: Myocarditis, pericarditis (rare)
- Secondary bacterial infections: Peritonsillar abscess, sinusitis
- Chronic fatigue: Fatigue may persist for weeks to months (post-viral fatigue syndrome)
- Malignancy: Associated with Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma (long-term)

✅ Model Answer:
• Indications for steroids (corticosteroids):
- Severe pharyngitis: With impending airway obstruction (significant tonsillar hypertrophy, stridor)
- Severe systemic symptoms: Persistent fever, severe malaise
- Hemolytic anemia: Autoimmune hemolytic anemia complicating EBV
- Thrombocytopenia: Severe thrombocytopenia with bleeding
- Neurologic complications: Encephalitis, meningitis, transverse myelitis
• Typical regimen:
- Prednisone 1-2 mg/kg/day (max 60-80 mg/day) for 3-5 days, then taper
- NOT recommended for routine management of uncomplicated mononucleosis.
• Evidence: Steroids may reduce symptoms temporarily but do not shorten the course of the disease.

✅ Model Answer:
• Splenomegaly management:
- Avoid contact sports: For 4-6 weeks (or until spleen size returns to normal on ultrasound).
- Activities to avoid: Football, basketball, soccer, wrestling, martial arts, weightlifting, and any activity with risk of abdominal trauma.
- Allowed activities: Walking, jogging (if no pain), non-contact exercises.
- Monitoring: Abdominal ultrasound (spleen size) if clinically indicated or if splenomegaly is significant.
- Signs of splenic rupture: Sudden left upper quadrant pain, shoulder pain (Kehr's sign), hypotension, tachycardia — medical emergency.
- Normalization: Spleen size usually returns to normal by 3-6 weeks.

✅ Model Answer:
• Prognosis:
- Excellent for most immunocompetent adolescents (self-limited illness).
- Symptoms: Fever and pharyngitis usually resolve in 1-2 weeks; fatigue may persist for 2-4 weeks (rarely longer).
- Fatigue: Post-viral fatigue can last for months in a small percentage of patients.
- Recurrence: EBV infection is lifelong (latent in B-cells); reactivation can occur (especially in immunocompromised patients) but is rare in healthy hosts.
- Mortality: Extremely low (<0.1%) — usually from splenic rupture or airway obstruction.
• Long-term:
- No permanent sequelae in most patients.
- Chronic EBV: Rare, associated with immunodeficiency.
- Malignancy: EBV is associated with Burkitt lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma (long-term, but risk is very low in immunocompetent).
- Vaccination: No EBV vaccine currently available.
- Counseling: Reassurance about recovery, activity restrictions, and follow-up.