Cutaneous B-lymphoblastic lymphoma with IL3/IgH translocation presenting with hypereosinophilia and acute endocarditis.

Hypereosinophilia is a rare phenomenon associated with childhood malignancy, predominantly acute lymphoblastic leukaemia. Causation is unclear and likely to have multiple mechanisms. We report a six year old boy presenting with hypereosinophilia and associated Loeffler endocarditis. Three months following his initial hypereosinophilia he developed cutaneous B-lymphoblastic lymphoma. Re-analysis of apparently uninvolved bone marrow, taken at initial presentation, revealed a single, previously unidentified, t(5;14)(q31;q32) positive cell. Using fluorescent in situ hybridisation, we demonstrate IL3/IgH@ fusion in cutaneous lymphoma cells. Our case confirms the association of hypereosinophilia and B-lymphoblastic lymphoma and strengthens the association between IL3 hypersecretion and hypereosinophilia.