A 1-year-old boy presenting with roseola accompanied by bilateral eyelid oedema and acute infectious mononucleosis syndrome caused by human herpesuvirus-6B: a case report.

Bilateral eyelid oedema, also known as Hoagland sign, is a specific physical sign of infectious mononucleosis (IM) syndrome caused by Epstein-Barr virus (EBV) infection in older children and adolescents. IM syndrome, which is mainly caused by EBV or cytomegalovirus infection, has milder symptoms in young children than in older children and adolescents. The human herpesvirus 6B (HHV-6B) causes roseola infantum (sixth disease) and various complications in children younger than 2 years; however, bilateral eyelid oedema and IM syndrome are rarely reported. We report the case of a 1-year-old boy with bilateral upper eyelid oedema and severe IM syndrome, including pancytopenia with an increased atypical lymphocyte count, purpura due to thrombocytopenia, and elevated liver enzyme and ferritin levels. Metagenomic next-generation sequencing indicated active HHV-6B infection. The patient improved within 1 week without any specific treatment. Our experience with this case suggests that the presentations observed should be considered rare complications of HHV-6B infection.