World Health Organization‐defined eosinophilic disorders: 2017 update on diagnosis, risk stratification, and management

Abstract

Disease overview: The eosinophilias encompass a broad range of nonhematologic (secondary or reactive) and hematologic (primary, clonal) disorders with potential for end-organ damage.Diagnosis: Hypereosinophilia has generally been defined as a peripheral blood eosinophil count greater than 1500/mm 3 and may be associated with tissue damage. After exclusion of secondary causes of eosinophilia, diagnostic evaluation of primary eosinophilias relies on a combination of morphologic review of the blood and marrow, standard cytogenetics, fluorescent in situ-hybridization, flow immunocytometry, and T-cell clonality assessment to detect histopathologic or clonal evidence for an acute or chronic myeloid or lymphoproliferative disorder.Risk stratification: Disease prognosis relies on identifying the subtype of eosinophilia. After evaluation of secondary causes of eosinophilia, the 2016 World Health Organization endorses a semimolecular classification scheme of disease subtypes which includes the major category "myeloid/ lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1 or with PCM1-JAK2," and the "MPN subtype, chronic eosinophilic leukemia, not otherwise specified" (CEL, NOS). Lymphocyte-variant hypereosinophilia is an aberrant T-cell clone-driven reactive eosinophila, and idiopathic hypereosinophilic syndrome (HES) is a diagnosis of exclusion. Risk-adapted therapy:The goal of therapy is to mitigate eosinophil-mediated organ damage. For patients with milder forms of eosinophilia (e.g., < 1500/mm 3 ) without symptoms or signs of organ involvement, a watch and wait approach with close-follow-up may be undertaken. Identification of rearranged PDGFRA or PDGFRB is critical because of the exquisite responsiveness of these dis-

Left ventricular rotational mechanics in hypereosinophilic syndrome—Analysis from the three‐dimensional speckle‐tracking echocardiographic MAGYAR‐Path Study

“…1,2 HES is characterized by peripheral eosinophilia and eosinophilic tissue/end-organ damage. 1,2 HES is characterized by peripheral eosinophilia and eosinophilic tissue/end-organ damage.…”

“…1,2 HES is characterized by peripheral eosinophilia and eosinophilic tissue/end-organ damage. 2 The clinical presentation of HES is extremely highly variable ranging from a relatively asymptomatic disease to endomyocardial fibrosis. 1 Regarding the latest consensus, several clinical subtypes/ categories have been identified that are different from the previous categories and definitions.…”

How I investigate Eosinophilia

“…Eosinophils are terminally differentiated granulocytes that are produced in the bone marrow via a collection of transcription factors and cytokines including interleukin 5 (IL‐5), interleukin 3 (IL‐3), and granulocyte macrophage colony stimulating factor (GM‐CSF) . Maturation occurs in the bone marrow over a five‐day period, and mature cells are released into circulation.…”

“…Normal eosinophil percentage is between 1%‐6% in the bone marrow and 3%‐5% in the peripheral blood, equating to an absolute peripheral eosinophil count (AEC) of 0.35‐0.5 × 10 9 /L . Eosinophilia is arbitrarily designated as mild (up to 1.5 × 10 9 /L), moderate (1.5‐5 × 10 9 /L), and severe (>5 × 10 9 /L) . Workup of eosinophilia to exclude a clonal process would be warranted in patients with persistent, unexplained eosinophilia.…”

The Diagnostic Work-Up of Hypereosinophilia

“…An algorithm that may facilitate the identification of the underlying cause is recommended in the evaluation of patients with HE [5] (Fig. 1).…”