What is the clinical presentation of infectious mononucleosis in pediatric patients?

Clinical Presentation of Infectious Mononucleosis in Children

Infectious mononucleosis in children presents with a classic triad of fever, tonsillar pharyngitis, and cervical lymphadenopathy, though the clinical picture varies significantly by age, with children under 10 years typically experiencing asymptomatic or nonspecific illness while adolescents develop the full syndrome. 1, 2

Age-Dependent Clinical Manifestations

Young Children (Under 10 Years)

• Primary EBV infection is usually asymptomatic or presents with nonspecific symptoms that may not be recognized as infectious mononucleosis 2
• When symptomatic, younger children may present with malaise, fever, and a mononucleosis-like syndrome featuring lymphadenopathy (cervical), sore throat, and myalgia 3

Adolescents and Older Children (Over 10 Years)

• The classic triad emerges: fever, tonsillar pharyngitis, and lymphadenopathy 1, 4
• Most commonly affects children aged 15-24 years with full symptomatic presentation 1

Cardinal Clinical Features

Constitutional Symptoms

• Fever is typically mild and occurs early in the disease course 1, 2
• Profound fatigue is characteristic but tends to resolve within three months 1
• Malaise, headache, and myalgia are common accompanying symptoms 3, 1

Oropharyngeal Findings

• Sore throat and tonsillar pharyngitis with or without tonsillopharyngeal erythema 3, 1
• Pharyngitis may be accompanied by exudates mimicking streptococcal infection 5

Lymphatic System Involvement

• Cervical lymphadenopathy is a hallmark feature, with generalized lymphadenopathy occurring in many cases 3, 1
• Lymph nodes are typically tender and enlarged 4

Characteristic Facial Findings

• Periorbital and/or palpebral edema, typically bilateral, occurs in one-third of patients - this is a distinctive feature that helps differentiate IM from other causes of pharyngitis 1

Organomegaly

• Splenomegaly occurs in approximately 50% of cases 1
• Hepatomegaly is present in approximately 10% of cases 1
• Hepatosplenomegaly may be accompanied by abdominal pain 6, 7

Dermatologic Manifestations

• A maculopapular rash occurs in 10-45% of cases, typically widely scattered and erythematous 3, 1
• The rash may resemble other viral exanthems 1

Laboratory Findings

Hematologic Changes

• Peripheral blood leukocytosis is observed in most patients, with lymphocytes comprising at least 50% of the white blood cell differential count 1
• Atypical lymphocytes constitute more than 10% of the total lymphocyte count - this is a key diagnostic feature 1
• Relative lymphocytosis with atypical lymphocytes is characteristic 5

Hepatic Involvement

• Elevated alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total bilirubin (TBil), and indirect bilirubin (IBil) indicate liver damage 7
• Hepatitis occurs as part of the systemic illness 6

Myocardial Markers

• Elevated creatine kinase (CK), CK-MB, and lactate dehydrogenase (LDH) may indicate myocardial involvement 7

Distinguishing Features from Other Causes of Pharyngitis

The presence of conjunctivitis, coryza, cough, and diarrhea strongly suggests a viral etiology other than EBV 5. In contrast, EBV-associated infectious mononucleosis presents with the characteristic triad plus periorbital edema, generalized lymphadenopathy, and splenomegaly - features not typically seen with other respiratory viruses 3, 5, 1.

Severe Complications to Monitor

Life-Threatening Manifestations

• Spontaneous splenic rupture occurs in 0.1-0.5% of patients and is potentially life-threatening 1
• Acute upper airway obstruction may occur 6
• Hematological complications including anemia, thrombocytopenia, and neutropenia 3

Neurological Complications

• Seizures, reduced alertness, and focal neurologic findings may occur in severe cases 3
• Headache and confusion can be prominent 3, 6

Other Serious Complications

• Acute renal failure 6
• Hepatitis with significant liver enzyme elevation 6, 7
• Cardiomyopathy/myocarditis 3
• Polymicrobial bacteremia and septic complications in immunocompromised states 6

Clinical Pitfalls

Do not assume all pharyngitis with lymphadenopathy in children is streptococcal - the overlap between streptococcal and viral pharyngitis is broad, and EBV should be considered when generalized lymphadenopathy, splenomegaly, or periorbital edema are present 3, 1.

Avoid prolonged steroid therapy in uncomplicated cases - there is insufficient evidence for efficacy in symptom control, and prolonged use may lead to severe complications including septic shock and polymicrobial infections 6.

Consider infectious mononucleosis as a risk factor for chronic fatigue syndrome - patients should be counseled about the possibility of prolonged fatigue lasting beyond the acute illness 1.