Infectious mononucleosis

Infectious mononucleosis (also known as glandular fever) is the term for infection with Epstein-Barr virus (EBV). The infection classically occurs in teenagers and young adults, hence its popular name kissing disease. It is usually a clinical diagnosis, with confirmation by serum testing, but may have suggestive findings on imaging.

Epidemiology

Exposure to Epstein-Barr virus is extremely widespread: 90% of adults are seropositive. When acquired during childhood it often remains subclinical but of those who acquire it during adolescence or young adulthood, 25% will become symptomatic ⁵. In about 5% of cases, cytomegalovirus (CMV) is the causative pathogen for infectious mononucleosis.

Clinical presentation

• fever
• tonsillitis
• lymphadenopathy and splenomegaly
  • occasionally hepatosplenomegaly
• fatigue
• occasionally: rash

Complications

• splenic rupture: may be spontaneous but is quite rare⁶
• splenic infarction ³

Pathology

It was originally called "mononucleosis" after abnormal mononuclear cells were found in patients with the clinical syndrome.

EpsteinThe epstein-Barr virus is in the herpesvirus class and is also called human herpesvirus 4. It is thought to be spread primarily through a person-to-person route through salivary secretions. The Epstein-Barr virus infects B-cells in the lymphoid tissue. Like other herpes viruses, it becomes a lifelong chronic infection with periodic shedding of virus.

Elevated transaminases are occasionally seen.

Radiographic features

Diagnosis is usually through serum lab work which shows lymphocytosis and a positive heterophile antibody test. Imaging is usually not necessary, but certain findings on imaging can be suggestive:

CT

• splenomegaly
  • possible splenic rupture⁶
  • splenic infarction has been reported ³
• generalised lymphadenopathy, including cervical lymphadenopathy
• tonsillar enlargement
• dacryoadenitis
• possible hepatomegaly

Treatment and prognosis

Symptomatic therapy is usually sufficient. Athletes are encouraged to discontinue sports during the acute phase (<3-4 weeks) to lower the risk of splenic rupture ².

Complications

• myocarditis rarely seen ⁴
• CNS infections rarely seen ⁴

Differential diagnosis

Imaging differential diagnoses include:

• acute HIV infection
• acute CMV infection (usually more clinically mild than EBV)
• non-Hodgkin lymphoma
• leukaemia