Eosinophilia/Hypereosinophilia in the Setting of Reactive and Idiopathic Causes, Well-Defined Myeloid or Lymphoid Leukemias, or Germline Disorders

Abstract

Objectives To report the findings of the 2019 Society for Hematopathology/European Association for Haematopathology Workshop within the categories of reactive eosinophilia, hypereosinophilic syndrome (HES), germline disorders with eosinophilia (GDE), and myeloid and lymphoid neoplasms associated with eosinophilia (excluding entities covered by other studies in this series). Methods The workshop panel reviewed 109 cases, assigned consensus diagnosis, and created diagnosis-specific sessions. Results The most frequent diagnosis was reactive eosinophilia (35), followed by acute leukemia (24). Myeloproliferative neoplasms (MPNs) received 17 submissions, including chronic eosinophilic leukemia, not otherwise specified (CEL, NOS). Myelodysplastic syndrome (MDS), MDS/MPN, and therapy-related myeloid neoplasms received 11, while GDE and HES received 12 and 11 submissions, respectively. Conclusions Hypereosinophilia and HES are defined by specific clinical and laboratory criteria. Eosinophilia is commonly reactive. An acute leukemic onset with eosinophilia may suggest core-binding factor acute myeloid leukemia, blast phase of chronic myeloid leukemia, BCR-ABL1–positive leukemia, or t(5;14) B-lymphoblastic leukemia. Eosinophilia is rare in MDS but common in MDS/MPN. CEL, NOS is a clinically aggressive MPN with eosinophilia as the dominant feature. Bone marrow morphology and cytogenetic and/or molecular clonality may distinguish CEL from HES. Molecular testing helps to better subclassify myeloid neoplasms with eosinophilia and to identify patients for targeted treatments.

Diagnostic spectrum of hypereosinophilia based on bone marrow pathology: 10 years' experience at a tertiary care hospital

“…According to the report of the 2019 society for hematopathology/European Association for hematopathology workshop, BM morphological evaluation based on robust criteria may be helpful to identify MN with or without clonal markers 3 . Recently published WHO/ICC guidelines included bone marrow morphology as diagnostic criteria for CEL 19,20 .…”

“…According to the report of the 2019 society for hematopathology/European Association for hematopathology workshop, BM morphological evaluation based on robust criteria may be helpful to identify MN with or without clonal markers. 3 Recently published WHO/ICC guidelines included bone marrow morphology as diagnostic criteria for CEL. 19,20 Therefore, if HE persists for more than 4 weeks, the possibility of CEL should be considered by applying a more stringent morphological criteria even if no clear clonal marker is expressed.…”

“…Absolute eosinophil count (AEC) from peripheral blood (PB) less than 0.5 × 10 9 /L is considered to be within the normal range. Increase in AEC can be classified into the following according to the degree of increment: mild eosinophilia (0.5–1.5 × 10 9 /L), moderate eosinophilia (1.5–5.0 × 10 9 /L), and marked eosinophilia (>5 × 10 9 /L) 3 . Hypereosinophilia (HE) is usually defined as an increase in AEC greater than 1.5 × 10 9 /L from PB.…”

“…following according to the degree of increment: mild eosinophilia (0.5-1.5 Â 10 9 /L), moderate eosinophilia (1.5-5.0 Â 10 9 /L), and marked eosinophilia (>5 Â 10 9 /L). 3 Hypereosinophilia (HE) is usually defined as an increase in AEC greater than 1.5 Â 10 9 /L from PB. The various etiologies of HE can be broadly categorized into primary and secondary HE.…”

Myeloid/Lymphoid Neoplasms with Eosinophilia and Platelet Derived Growth Factor Receptor Alpha (PDGFRA) Rearrangement

“…HES is defined as HE with organ damage such as fibrosis (lung, heart, digestive tract, skin, and others), thrombosis with or without thromboembolism, cutaneous or mucosal erythema, edema/angioedema, ulceration, pruritus, and eczema, as well as peripheral or central neuropathy with chronic or recurrent neurologic deficit. Viewed in terms of the HES, primary HES is analogous to clonal eosinophilia; secondary HES is cytokine driven eosinophilia and idiopathic HES is end-organ damage directly attributable to HE and no discernible underlying cause of the HE (14,38,(41)(42)(43).…”