Does hypereosinophilic syndrome precede common B acute lymphoblastic leukaemia in childhood? A case report

Hypereosinophilic syndrome (HES) and the association of hypereosinophilia with acute lymphoblastic leukaemia (ALL) are both rare in children. Some acute myelogenous leukaemias can present with eosinophilia, but the relationship between HES and ALL is not well known and is rarer than the relationship between HES and acute myelogenous leukaemia. Patients are diagnosed with HES when no cause is found to explain the eosinophilia leading to end organ damage. For this reason, it is recommended that patients presenting with hypereosinophilia be carefully assessed to exclude any malignant clonal proliferation. HES may present with severe clinical manifestations such as high leucocyte count, anaemia, thrombocytopaenia, hepatosplenomegaly or cardiac and neurological involvement, all of which are primarily features of myeloproliferative disorders. Some patients with HES can develop chronic eosinophilic leukaemia. Successful treatment of HES with agents used in chronic myeloid leukaemia supports the idea that HES can be a chronic myeloid disorder. There are few cases reporting an association between ALL and hypereosinophilia that precedes or is concomitant with ALL. Here we report the case of a 14-year-old girl who developed common B ALL 7 months after diagnosis and treatment of HES. Interestingly, eosinophilia was not concomitant with the diagnosis of ALL.