Infectious mononucleosis is defined as any blood lymphocytosis induced in response to an infectious agent.
Usually greater than 50% of the circulating white cells are lymphocytes, more than 10% of which have the morphology of reactive lymphocytes (Figure 52–1).
Table 52–1 lists the etiologic agents that produce mononucleosis.
— A sore throat is preceded by 1 to 2 weeks of lethargy.
— Epstein-Barr virus (EBV) generally is the cause.
Glandular form without pharyngitis:
— Lymph node enlargement occurs.
— The usual cause is agents other than EBV (eg, Toxoplasma gondii).
— Lethargy with fever or diarrhea without pharyngitis, usually as a consequence of cytomegalovirus (CMV), is characteristic.
A–D. Blood films from patients with Epstein-Barr virus–induced mononucleosis. These reactive lymphocytes exhibit the characteristic changes seen in patients with infectious mononucleosis: large lymphocytes with abundant cytoplasm. The cytoplasmic margin often spreads around (is indented by) neighboring red cells and the margin may take on a densely basophilic coloration. This type of reactive T lymphocyte may be seen a variety of diseases and is not specific changes but are characteristic. (Reproduced with permission from Lichtman’s Atlas of Hematology, www.accessmedicine.com.)
TABLE 52–1ETIOLOGIC AGENTS ASSOCIATED WITH MONONUCLEOSIS SYNDROME |Favorite Table|Download (.pdf) TABLE 52–1ETIOLOGIC AGENTS ASSOCIATED WITH MONONUCLEOSIS SYNDROME
|Epstein-Barr virus ||Hepatitis A |
|Cytomegalovirus ||Adenovirus |
|Human immunodeficiency virus ||Toxoplasma gondii |
|Human herpes virus-6 ||Bartonella henselae |
|Metapneumovirus ||Brucella abortus |
|Rubella || |
ETIOLOGY AND PATHOGENESIS
The caused is two members of the herpes virus family: EBV or CMV.
After the early phase of fever, which lasts for 3 to 7 days, laboratory abnormalities include a blood lymphocyte proportion greater than 50%, often with greater than 10% reactive lymphocytes.
Table 52–2 lists other complications of EBV and CMV mononucleosis.
TABLE 52–2COMPLICATIONS IN PATIENTS WITH EBV OR CMV MONONUCLEOSIS |Favorite Table|Download (.pdf) TABLE 52–2COMPLICATIONS IN PATIENTS WITH EBV OR CMV MONONUCLEOSIS
| ||EBV ||CMV |
|Hemolytic anemia ||++ ||+ |
|Thrombocytopenia ||+ ||+ |
|Aplastic anemia ||+ ||– |
|Splenic rupture ||+ ||– |
|Jaundice (> age 25 years) ||++ ||++ |
|Guillain-Barré* ||+ ||++ |
|Encephalitis* ||++ ||+/– |
|Pneumonitis* ||+/– ||+ |
|Myocarditis* ||+ ||– |
|B-cell lymphoma ||+ ||– |
|Agammaglobulinemia ||+ ||– |
FEATURES OF MONONUCLEOSIS CAUSED BY EACH ETIOLOGIC AGENT
Table 52–3 list the signs and symptoms associated with EBV and CMV mononucleosis.
Target cell for EBV mononucleosis is the B lymphocyte.
Target cell for CMV mononucleosis is the macrophage.
The “mononucleosis” for both is ...
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