Infectious mononucleosis

Infectious mononucleosis
Updated: 09/10/2020
© Jun Wang, MD, PhD

General features
  • Febrile illness
  • EB virus associated
  • Spread by intimate contact, including breast feeding, saliva exchange and other sexual contacts
  • Human likely major reservoir
  • More common in young adults
  • Higher risk for EBV associated malignancies, such as Hodgkin lymphoma, Burkitt lymphoma
Clinical presentations
  • Most asymptomatic
  • Incubation 1-2 months
  • Triad of fever, tonsillar pharyngitis, and lymphadenopathy
  • Other nonspecific presentations: fatigue,
  • Hepatomegaly, jaundice, splenomegaly, etc
  • Risk of fatal spontaneous spleen rupture
Key pathogenesis
  • EB virus infection of B cells
  • Infects reticular endothelial system (liver, spleen, lymph nodes, etc) through circulation
  • B cells produce antibodies against EBV protein components
  • T cells eliminate infected B cells
  • Inflammatory reactions associated with clinical presentations
  • B cell malignancy may develop due to uncontrolled proliferation if T cell function impaired
Key Laboratory findings
  • Lymphocytosis
  • Atypical lymphocytes
  • Hemolytic anemia associated with anti-i cold agglutinin
  • Abnormal liver function tests, usually self-limited
  • Heterophile antibodies (monospot test, ELISA)
  • EBV specific antibodies
  • PCR for EBV DNA quantification
Key morphological features
  • Large atypical lymphocytes with abundant basophilic cytoplasm and peripheral darkening, usually CD8+ T cells
Differential diagnosis
  • Pharyngitis caused by other microorganisms, including bacteria, CMV, HIV, toxoplasma, etc: microbiology studies, molecular studies
  • Drug reactions, including anticonvulsants (phenytoin, carbamazepine, isoniazid, etc): History, lab tests for EBV
  • Lymphomas: Tests to rule out monoclonal proliferation
Management
  • Supportive care
  • Corticosteroid/otolaryngologist consultation for airway obstruction
  • Antiviral treatment: acyclovir, etc
  • Avoiding splenic rupture, refrain from sports for at least 3 to 4 weeks


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