High and persistent fever with epatosplenomegaly and cytopenia

Key words: Infectious mononucleosis, Hemophagocytic lymphohistiocytosis, Hemophagocytic syndrome, Epstein-Barr virus

The case described is that of an 11-year-old child presenting with high fever, pharyngotonsillar exudate, submandibular strangles and hepatosplenomegaly. The elevated number of VCA IgM antibodies led to a diagnosis of infectious mononucleosis. The persistence of the fever for more than two weeks associated with thrombocytopenia and anaemia and the serious general conditions of the patient have induced the provider to perform a fine-needle bone marrow aspiration that has revealed the presence of macrophages in active hemophagocytosis. This condition, associated with other symptoms, has resulted in the diagnosis of a secondary hemophagocytic lymphohistiocytosis, a rare and serious complication of infectious mononucleosis.