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

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.