Search, Look, and See; Late Recognised Hypereosinophilic Syndrome with Deletion (4) (q12)

The hypereosinophilic syndrome (HES) is a group of rare disorders characterized by persistently high peripheral blood eosinophiles (≥ 1.5x109/L), and related signs or symptoms of organ involvement without secondary causes. Eosinophilia with recurrent genetic abnormalities (PDGFRA/B, FGFR1) comprises a minority of these patients. In this report, we aimed to point out a case with 4q12 deletion whose diagnosis and treatment were delayed for quite a while. The patient was followed for bronchial asthma for a long time and the recognition of hypereosinophilia yielded a suspicion for HES / Chronic eosinophilic leukemia (CEL). During the initial part of his diagnostic evaluation, there was an unawareness of the cryptic deletion which was a target for tyrosine kinases. The symptoms resolved and complete cytogenetic response was achieved with 100 mg imatinib continuing for 57 months.