Working Diagnosis:
Infectious Mononucleosis (IM) with splenic infarcts

Treatment:
The patient was treated supportively with conservative mesures including removal from contact sports and strenuous physical activity.

Outcome:
The patient was advised to abstain from strenuous physical activity and contact sports for three to four weeks. After this period, he began light, non-contact activity with the goal of returning to full contact sports between 4 to 6 weeks after diagnosis. He successfully completed the return to play protocol and was symptom free at the time of return to sport.

Author's Comments:
The typical features of infectious mononucleosis include fever, pharyngitis, adenopathy, fatigue, and atypical lymphocytosis. In athletes, the most concerning complication of infectious mononucleosis is splenomegaly and the associated risk of splenic rupture. Athletes returning to contact sports following infectious mononucleosis are at increased risk of splenic rupture secondary to abdominal trauma.

Return to play decisions are the most challenging part of managing athletes with infectious mononucleosis. The risk of splenic rupture in athletes is not well-studied but is reported to be between 0.1%-0.5% in the general population. Splenic rupture typically occurs between days 4-21 of symptomatic illness and this risk has not been found to correlate with clinical severity or lab findings.

As seen in this patient, there are several infectious mononucleosis clinical variants in which not all classic findings are present. As a Sports Medicine physician, one must keep these unusual presentations in mind given their potential severe and life-threatening complications.

Editor's Comments:
Epstein-Barr virus (EBV) is the primary virus responsible for infectious mononucleosis. EBV is one of the most common viral infections in the world and is transmitted primarily via oral secretions with symptoms typically occurring between 30 to 50 days following exposure to the virus. While the typical presentation includes the triad of fever, lymphadenopathy, and pharyngitis; IM can manifest with a myriad of symptoms as any organ system is at risk of being infected. Atypical IM accounts for about 15% of disease presentation in young adults so clinicians must maintain a high index of suspicion in adolescent and young adult populations. Splenomegaly is common with infectious mononucleosis and risk of splenic rupture must be considered with return to contact sports. Although risk of rupture is rare, the majority of cases occur within the first 31 days of symptom onset.

References:
Li Y, George A, Arnaout S, Wang JP, Abraham GM. Splenic Infarction: An Under-recognized Complication of Infectious Mononucleosis? Open Forum Infect Dis. 2018 Feb 17;5(3):ofy041. doi: 10.1093/ofid/ofy041. PMID: 29577060; PMCID: PMC5853003.


Putukian, Margot, et al. “Mononucleosis and athletic participation: an evidence-based subject review.” Clinical Journal of Sport Medicine 18.4 (2008): 309-315.
Sylvester, J. E., Buchanan, B. K., Paradise, S. L., Yauger, J. J., & Beutler, A. I. (2019). Association of Splenic Rupture and Infectious Mononucleosis: A Retrospective Analysis and Review of Return-to-Play Recommendations. Sports Health, 11(6), 543–549.

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