Advances in diagnosis of mastocytosis and hypereosinophilic syndrome

Abstract Mastocytosis and hypereosinophilic syndrome is very rare neoplastic hematopoietic diseases. Mastocytosis is characterized by expansion and accumulation of clonal tissue mast cells in skin and/or various internal organs, while hypereosinophilic syndrome manifests with an increased number of eosinophils in the peripheral blood and tissue damage. These diseases represent a diagnostic challenge, since they can have overlapping clinical and pathologic features. Recently, great advances in the molecular and immunophenotypic diagnosis of these two entities were achieved, contributing to the new World Health Organization (WHO) classification. The WHO classification of myeloid neoplasms has been revised in 2016 by adding several new entities and refinement of the 2008 WHO classification, in an attempt to incorporate up-to-date clinical, prognostic, morphologic, and molecular genetics data that emerged since 2008. Here we overview the recent advances in disease diagnosis, with a focus on the updated WHO classification, refined diagnostic criteria, and up-to-date molecular findings in these two rare diseases.