CEL-NOS

WHO 2022

Chronic eosinophilic leukaemia (CEL) is a multi-system disorder characterized by a sustained clonal proliferation of morphologically abnormal eosinophils and eosinophil precursors resulting in persistent hypereosinophilia in blood and bone marrow.

Several changes to the diagnostic criteria of CEL are introduced:

(1) the time interval required to define sustained hypereosinophilia

is reduced from 6 months to 4 weeks; (2) addition

of requirement for both clonality and abnormal bone marrow

morphology (e.g., megakaryocytic or erythroid dysplasia); and, (3)

elimination of increased blasts (≥2% in peripheral blood or 5-19%

in bone marrow) as an alternative to clonality. These criteria

improve the distinction between CEL and entities such as

idiopathic hypereosinophilic syndrome and hypereosinophilia of

unknown significance. As the criteria of CEL and its place

relative to other disorders with eosinophilia have become well

characterized, the qualifier “not otherwise specified” is no longer

needed and has been omitted from the name.