Infectious Mononucleosis: An Uncommon Presentation of a Common Disease—a Case Report

TL;DR

This case report describes a rare presentation of infectious mononucleosis in a young man, emphasizing the need for early diagnosis to avoid unnecessary tests.

Contribution

Highlights atypical presentation of IM without pharyngitis and advocates for early EBV testing to prevent misdiagnosis.

Findings

A 19-year-old male presented with fever and lymphadenopathy but no pharyngitis, mimicking malignancy.

EBV serology confirmed the diagnosis of atypical infectious mononucleosis.

Early recognition of IM prevented unnecessary invasive investigations and reduced healthcare burden.

Abstract

Infectious mononucleosis (IM), caused by the Epstein–Barr virus (EBV), typically presents with fever, pharyngitis, and lymphadenopathy. However, atypical presentations may occur, complicating the diagnostic process. A 19‐year‐old male presented with high‐grade episodic fever, cervical lymphadenopathy, and severe constitutional symptoms. The clinical presentation raised concern for serious underlying conditions due to prominent lymphadenopathy. Laboratory evaluation demonstrated marked lymphocytosis with atypical lymphocytes and positive EBV serology, confirming the diagnosis of IM. The patient was managed conservatively and achieved complete recovery on follow‐up. This case highlights the importance of including atypical IM in the differential diagnosis of patients presenting with fever and lymphadenopathy. Early recognition of IM may prevent misdiagnosis and avoid unnecessary invasive and costly investigations, reducing patient harm and health care burden.

In patients with fever and lymphadenopathy, failure to consider infectious mononucleosis among the infectious causes, particularly when pharyngitis is absent, may shift the diagnostic focus toward malignancy, leading to unnecessary, invasive, and costly investigations, such as bone marrow examination. Early recognition of atypical infectious mononucleosis is therefore essential to prevent patient harm and reduce avoidable health care burden.

Atypical infectious mononucleosis without pharyngitis may mimic malignancy; early EBV testing enables accurate diagnosis and prevents unnecessary invasive investigations.

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