Diagnosis

Mononucleosis

Etiology

Cause [crs][b87][esg][qqd]

• Epstein-Barr virus (>90%)

• Other causes: Cytomegalovirus, Adenovirus, Toxoplasma gondii, adenovirus, Hepatitis A virus, HIV, rubella virus, herpes virus, group A beta-hemolytic streptococci

Pathophysiology

1. Virus is transmitted via intimate contact with body (oropharyngeal) secretions

2. Incubation period is long: 3-6 weeks

3. EBV infects the B cells in the oropharyngeal epithelium. Circulating B cells spread the infection to liver, spleen, and peripheral lymph nodes

4. This results in a humoral and cellular response to the virus

5. T-lymphocyte response is essential in the control of EBV infection; natural killer (NK) cells and predominantly CD8 cytotoxic T cells control proliferating B lymphocytes infected with EBV

6. EBV is a lifelong infection with periodic reactivation

7. The majority of patients recover without sequelae and develop lifelong immunity to controlling the dormant virus

8. Ineffective T-cell response (immunosuppresion) may result in excessive and uncontrolled B-cell proliferation, resulting in B-cell lymphomas

Complications [n8g][qqd]

• Spontaneous splenic rupture

• Airways obstruction due to oropharyngitis or massive lymphadenopathy

• Meningoencephalitis

• Autoimmune hemolytic anemia

• Pancytopenia: Thrombocytopenia, neutropenia

• Cardiac complications: Myocarditis, pericarditis

• Ocular complications: Episcleritis, uveitis, conjunctivitis

• Erythema multiforme

• Pancreatitis

• Parotitis

• Pnemonitis

• B-cell lymphoma

• Nasopharyngeal carcinoma

• Gastric carcinoma

• Posttransplant lymphoproliferative disorder (PTLD)

• Hemophagocytic lymphohistiocytosis (HLH)

Epidemiology

Incidence per 100.000 [bc8][ddo][esg][bsy][hp7][du5][3az][n8g][zvp][1ps][qqd]

Approach

• Blood test: WBC, thrombocyte, liver function test

• Heterophile antibody (monospot): [n8g]

  • + Negative 3–12 months postinfection

  • - Nonspecific: false positives due to acute infections and autoimmune diseases

• VCA IgM antibody:

  • + Specific

  • + Negative 3–12 months postinfection

• VCA IgG antibody:

  • Best test for diagnosis of past EBV infection

• EBNA-1 IgG antibody:

  • Best test to distinguish acute from convalescent EBV infection

• EA antibody:

  • + A marker of acute infection

  • - Absent in 20–40% of acute illnesses

• Immunoblot antibodies:

  • + Used to stage infection (acute, convalescent, past)

  • - Relatively expensive

• Blood viral load: best test to monitor severity of the infection

• Oral viral load:

  • Confirms past infection

  • Cannot be used to diagnose acute infection

• Peripheral blood smear: atypical lymphocytes

• Bone marrow smear

• Biopsy

• CT

Treatment

1. There is no specific treatment for infectious mononucleosis [qqd]

2. Supportive care:

   • Hydration

   • Rest

   • Nutritional intake

   • NSAIDs, paracetamol, throat sprays to treat fever, sore throat, and fatigue

3. No clinical evidence regarding acyclovir, valacyclovir, ganciclovir, or corticosteroids

4. Antibiotics can result in a generalized maculopapular rash

5. Hospitalization if complications: splenic rupture, airway compromise, dehydration, thrombocytopenia, hemolytic anemia, and neurologic complications.

Differential diagnoses

Adenovirus, Bacterial tonsillitis, Cytomegalovirus, Depression, Diphtheria, Drug eruptions, Encephalitis, Erythema multiforme, Fibromyalgia, Gianotti-Crosti syndrome, Guillain-Barre syndrome, Hemophagocytic lymphohistiocytosis, Herpes simplex, HIV, Influenza, Leukemia, Lyme disease, Meningitis, Mumps, Peritonsillar abscess, Pharyngitis, Posttransplant lymphoproliferative disorder, Rickettsia, Rubella, Scarlet fever, Splenic injury, Toxoplasmosis, Viral hepatitis