Eosinophilia characterized by a rare CCT6B mutation and responsive to tyrosine kinase inhibition: Case report and literature review.

Hypereosinophilic syndrome is a rare disorder arising from neoplastic, or idiopathic causes. The availability of NGS panels has increasingly identified rare mutations as underlying pathogenic events and have led to reclassification of cases of idiopathic hypereosinophilic syndrome as chronic eosinophilic leukemia(CEL). In this report, we describe a case of a young man with hypereosinophilia whose disease initially did not fit the WHO criteria for CEL but harbored a rare mutation in CCT6B gene. We report our experience in successfully treating this patient with multiple tyrosine kinase inhibitors and provide literature review of this rare entity including potential treatment strategies.