Snapshot A 15-year-old boy presents with 1 week of fever and sore throat. A few days ago, the patient had gone to an urgent care and had started taking amoxicillin for a presumed bacterial infection. On the 2nd day of antibiotics, he developed a rash. He works at a daycare center after school every weekday. On physical exam, he is found with a diffuse maculopapular rash as well as cervical lymphadenopathy and tonsillar exudates. A Monospot test was positive. He was counseled to stop the antibiotics and to avoid contact sports during this illness. Introduction Classification Epstein-Barr virus (EBV) or human herpesvirus-4 (HHV-4) an enveloped, linear double-stranded DNA virus transmitted via respiratory secretions login to view 1 more bullet causes mononucleosis Epidemiology incidence common demographics common in teens and young adults risk factors Asian descent login to view 1 more bullet living in endemic areas login to view 1 more bullet transplant recipient login to view 1 more bullet poor sanitation kissing daycare centers Pathogenesis binds to B-cells via CD21, acting as a B-cell mitogen can establish lifelong persistent infection in B-cells T-cell-mediated immunity controls the latent infection immunocompromised patients are at risk of reactivation Associated conditions lymphomas e.g., Burkitt lymphoma and central nervous system lymphoma nasopharyngeal carcinoma lymphoproliferative disease gastric carcinoma oral hairy leukoplakia in HIV patients Prognosis most cases resolve Presentation Symptoms fatigue pharyngitis maculopapular rash if patients with mononucleosis were treated with amoxicillin Physical exam fever posterior cervical lymphadenopathy hepatosplenomegaly palatal petechiae tonsillar exudate Studies Labs ↑ atypical lymphocytes on peripheral blood smear enlarged nuclei + Monospot test heterophile IgM antibodies detected by agglutination of sheep red blood cells Making the diagnosis based on clinical presentation and laboratory studies Differential Cytomegalovirus distinguishing factors can present with mononucleosis-like syndrome but can also present with more myalgias, arthralgias, and cough does not typically present with a sore throat and lymphadenopathy Treatment Management approach management is centered around supportive care and avoidance of contact sports, as patients are at risk of splenic rupture Conservative supportive care indication login to view 1 more bullet modalities login to view 2 more bullets Complications Splenic rupture Malignancy Hemolytic anemia treat with rituximab Guillain-Barre syndrome