What is the management for a 12-year-old male with splenomegaly and positive heterophile antibody but negative EBV antibodies, presenting with abdominal pain?

Management of Splenomegaly in a 12-Year-Old with Positive Heterophile Antibody Test

The 12-year-old male with splenomegaly, positive heterophile antibody test, and negative EBV antibodies should be managed conservatively with activity restriction for 4-6 weeks or until splenomegaly resolves, with no contact sports permitted during this period.

Diagnosis

This patient presents with a clinical picture consistent with infectious mononucleosis (IM) syndrome:

• Positive heterophile antibody test (Sept 4,2025)
• Abdominal pain
• Splenomegaly (11.7 cm, >90th percentile for age)

Diagnostic Considerations

• The positive heterophile antibody test strongly suggests infectious mononucleosis, despite negative EBV antibodies 1
• Heterophile antibodies typically become detectable between 6-10 days after symptom onset and increase through the second or third week of illness 1
• False-negative EBV-specific antibody results can occur in approximately 10% of patients, especially in children younger than 10 years 1
• The spleen size of 11.7 cm exceeds the 90th percentile (11.4 cm) for the patient's age group

Management Recommendations

Immediate Management

1. Activity restriction for 4-6 weeks or until splenomegaly resolves 2, 3

   • No contact sports or strenuous exercise while splenomegaly is present
   • This is critical to prevent splenic rupture, which occurs in 0.1-0.5% of IM cases 3

2. Supportive care

   • Adequate hydration
   • Analgesics for pain control (acetaminophen preferred)
   • Rest as tolerated

Monitoring

1. Serial clinical examinations to assess:

   • Resolution of splenomegaly
   • Improvement in abdominal pain
   • Development of any complications

2. Follow-up ultrasound in 4-6 weeks to document resolution of splenomegaly 2

3. Monitor for complications:

   • Splenic rupture (acute left upper quadrant pain, hypotension)
   • Splenic infarction (severe abdominal pain) 4, 5
   • Persistent symptoms beyond expected recovery time

Special Considerations

Differential Diagnosis

While infectious mononucleosis is the most likely diagnosis, other causes of splenomegaly with positive heterophile antibody should be considered:

• CMV infection (can cause false-positive heterophile test) 1
• Toxoplasmosis
• Leukemia/lymphoma (particularly if splenomegaly persists)
• Chronic myeloid leukemia (rare in children but can present with splenomegaly) 1

Return to Activities

• Gradual return to normal activities after 4-6 weeks if splenomegaly has resolved 3
• Avoid contact sports for at least 8 weeks or until documented resolution of splenomegaly 3, 6
• Athletes may require 3-6 months to regain full physical condition 6

Warning Signs Requiring Urgent Evaluation

• Severe or worsening abdominal pain (especially left upper quadrant)
• Dizziness or lightheadedness
• Shoulder pain (Kehr's sign)
• Worsening fatigue or pallor

Prognosis

The prognosis for infectious mononucleosis is generally excellent, with most patients having complete recovery. However, fatigue may persist for several weeks to months in some cases 3.