Mononucleosis differential diagnosis

Overview

• Acute mononucleosis, acute cytomegalovirus infection and toxoplasma gondii infection have similar clinical presentations.

• In addition, since their management is much the same, it is not always helpful, or possible, to distinguish between infectious mononucleosis and cytomegalovirus infection.
• However, in pregnant women, it is imperative to differentiate mononucleosis from toxoplasmosis as toxo is associated with significant consequences in the fetus.

• Acute HIV infection can also mimic signs similar to those of infectious mononucleosis, and tests should be performed in pregnant women for the same reason as toxoplasmosis.

• Other conditions to be differentiated from infectious mononucleosis include:

• Leukemia,
• Tonsillitis,
• Pharyngitis,
• Diphtheria,
• Common cold,
• Adenovirus infections
• Influenza

Differentiating mononucleosis from other causes with similar presentation

Pharyngitis

• EBV infection may cause either exudative or non-exudative pharyngitis and both of which is colonized by streptococcus pyogens present in the oropharynx

• Petechial hemorrhages present in the posterior oropharynx are characteristic of infectious mononucleosis

• Edema of the uvula is rare but if present differentiates mononucleosis from all other types of pharyngitis

Cytomegalovirus vs. EBV

• Almost all cases of mononucleosis are caused by the EBV; however, cytomegalovirus can produce a similar symptoms but milder and with less throat pain and no rash.

• Extreme fatigue, bilateral supra-orbital edema, tender bilateral lymphadenopathy, splenomegaly, elevated liver function tests are characteristic of mononucleosis and may or may not be present in cytomegalovirus infections.

• Although, due to the presence of the atypical lymphocytes on the blood smear in both conditions, some physicians confusingly used to include both infections under the diagnosis of "mononucleosis," though EBV is by definition the infection that must be present for this illness.

• An elevated antibody (IgM) titer specific for CMV helps to differentiate it from EBV infection

Toxoplasmosis vs. EBV

• In pregnant women, it is imperative to differentiate mononucleosis from toxoplasmosis as toxo is associated with significant consequences in the fetus.

• In contrast to tender bilateral lymphadenopathy observed in patients with mononucleosis, toxo causes unilateral lymphadenopathy.

• In addition, normal to moderately elevated white blood cell count, particularly the number of lymphocytes is observed with mononucleosis; while, in patients infected with toxo, the white blood cell count is typically normal.

Viral hepatitis vs. EBV

• Liver function tests may show a moderate elevation of liver enzyme levels in nearly 90% of patients infected with mononucleosis. On the contrary, there is a significant increase in enzyme levels observed in patients with viral hepatitis.

References

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