Infectious Mononucleosis

A 4-year-old male child presented with a fever of 101 °F for 2 days. He was otherwise active and accepting feeds. The rest of the history was unremarkable. On examination, he was alert, and his vital signs were normal. There were no rashes or palpable lymph nodes. Throat examination revealed bilateral hyperemic tonsils. A diagnosis of viral tonsillitis was made. He was started on oral paracetamol. On review after 48 h, the fever persisted, and he was also not taking oral feeds well. On examination, he had bilaterally palpable and firm posterior cervical lymph nodes, and throat examination revealed bilaterally enlarged and congested tonsils with exudates. Streptococcal tonsillitis was suspected, throat culture was sent, and the child was started on amoxicillin. The parents came back after 48 h, as he had developed pain on swallowing, drooling of saliva, and a maculopapular rash on face and trunk and fever continued. A systemic examination was done which showed hepatomegaly in addition to previous findings. A provisional diagnosis of infectious mononucleosis (IM) was made, and the child was admitted. Intravenous fluids and analgesics were started and antibiotics were stopped. Investigations were sent, and reports showed elevated total leukocyte count with lymphocytosis. Peripheral smear examination revealed atypical lymphocytes that constituted 11% of total cells. Epstein–Barr virus (EBV) viral capsid antigen (VCA) IgM titers were >160 U/mL (reference range <40), and IgG was 40 U/mL (reference range <20). Thus, the diagnosis of IM was confirmed and the child was managed with supportive care.