Identical twin brothers concordant for Langerhans’ cell histiocytosis and discordant for Epstein-Barr virus-associated haemophagocytic syndrome

We report on identical twin brothers, one of whom presented at 14 months of age with fever and clinical, laboratory and histological evidence of Epstein-Barr virus-associated haemophagocytic syndrome (EBV-AHS) and 4 months later with typical signs and symptoms of Langerhans’ cell histiocytosis (LCH). The other twin, without previous symptoms, also displayed at that time LCH associated with signs of recent EBV infection, but without symptoms of haemophagocytic syndrome. No mutation in the SH2D1A gene, as observed in X-linked lymphoproliferative disease, or in the perforin gene as observed in some cases of hereditary haemophagocytic syndrome, was found. Conclusion:the occurrence of haemophagocytic syndrome and Langerhans’ cell histiocytosis, although genetically based, can be triggered by environmental agents and viruses, in particular Epstein-Barr virus.