Life-threatening haemolytic anaemia and infectious mononucleosis. A case report

A 36-year-old man with infectious mononucleosis presented with massive intravascular haemolytic anaemia. The diagnosis was established by a positive Paul-Bunnell test, the demonstration of IgM antibodies against Epstein-Barr virus capsid, and IgG antibody to early antigen. The direct and indirect antiglobulin tests were negative; the pathogenesis of the severe haemolysis was attributed to the temporary synthesis of anti-i cold agglutinin having a high thermal amplitude. Although life-threatening, the episode was short-lived and responded to supportive therapy with blood transfusion and folate administration only. This case illustrates a rare association between severe haemolytic anaemia and infectious mononucleosis, it emphasizes the value of IgM-specific fluorescent antibody tests in diagnosis when patients have otherwise unexplained haemolysis.