Splenic Infarcts in a 22-Year-Old Boxer With Acute Epstein-Barr Virus Infection Without a Predisposing Haematological Disease.

Splenic infarction is a rare complication of Epstein-Barr virus (EBV) infectious mononucleosis, particularly in the absence of pre-existing haematological disease. We report a 22-year-old male with ulcerative colitis on azathioprine who presented with fever, sore throat, malaise, cervical lymphadenopathy and left upper quadrant pain. Imaging revealed splenomegaly with multiple wedge-shaped hypodense lesions consistent with splenic infarction. Laboratory investigations demonstrated marked lymphocytosis, reduced protein C, and a heterozygous Factor V Leiden mutation. EBV viral capsid antigen immunoglobulin M (IgM) was positive. The patient was managed conservatively with intravenous fluids, prophylactic anticoagulation and temporary suspension of azathioprine. Splenic infarction is an uncommon but important manifestation of EBV-associated infectious mononucleosis. Postulated mechanisms include rapid splenic enlargement, transient hypercoagulability, and immunological processes. Conservative management is appropriate in most cases. Clinicians should maintain a high index of suspicion for splenic infarction in patients with infectious mononucleosis who report left upper quadrant pain. Early diagnosis is essential to prevent complications such as splenic rupture, and patients must be counselled to avoid contact sports during recovery.