Eosinophilia and Hypereosinophilic Disorders – Update on Etiopathogeny, Classification and Clinical Approach

Abstract

Eosinophils are innate immune leukocytes recruited in large numbers to sites of allergic inflammation and parasitic infections. Recent studies show additional pleiotropic effects of recruited eosinophils impacting immunomodulation, tissue homeostasis and repair. Pathologic conditions accompanied by blood eosinophilia are quite frequent in medical practice and may raise serious differential diagnosis problems in severe cases, that require a multidisciplinary approach. Hypereosinophilia may be reactive to other diseases or primary, representing hypereosinophilic syndromes, that are diagnosed based on clinical and laboratory criteria, according to actual international guidelines. The etiopathogenic diagnosis is difficult and delayed in many cases and clinical evolution may be severe, with multiorgan involvement and poor prognosis. Some cases remain idiopathic, despite exhaustive investigation.This paper aims to review the most recent data in the literature referring to the role of eosinophils in human pathology, diagnostic criteria and treatment strategies of hypereosinophilic syndromes, actual classification and to draw some useful recommendations in clinical practice.

Idiopathic hypereosinophilic syndrome with cutaneous involvement: a comparative review of 32 cases

“…The FIP1L1/PDGFRA -associated fusion gene-positive patients show a good response to imatinib and a favourable prognosis while elevated tryptase levels show a poor response to imatinib, conferring a poor prognosis 39. Furthermore, patients with high serum IgE levels and angio-oedema usually show a good prognosis whereas leucocytosis, myeloblasts in blood and congestive cardiac failure are among the indicators of a poor prognosis in patients with HES 40…”

Hypereosinophilic syndrome complicated by severe vascular damage and gangrene

“…HES is a rare heterogeneous condition with different subtypes, including myeloproliferative, lymphocytic, overlap, familial, and undefined types. However, myeloproliferative HES (M-HES) and lymphocytic HES (L-HES) represent the most common subtypes 1, 2. In general, the most common systems involved in HES are the hematologic, cutaneous, cardiovascular, pulmonary, and neurologic, among others.…”

“…Diagnostic criteria for HES include the following: peripheral blood eosinophilia with eosinophil counts >1500/μL for at least 6 months; no evidence of parasitic, allergic, or other known causes of eosinophilia; presumptive signs; and symptoms of multiple organ involvement. The most common cutaneous features of HES are erythematous pruritic papules and nodules, angioedema, and urticarial plaques 1, 2, 3. We here describe a patient with HES presenting with cutaneous eosinophilic vasculitis and severe vascular damage resulting in digital gangrene.…”

Mast cell activation syndromes ‑ evaluation of current diagnostic criteria and laboratory tools in clinical practice (Review)

“…A subgroup of patients with MCDs may associate concomitant blood or tissue hypereosinophilia (HE), possibly due to shared roles of MCs and eosinophils in many diseases, classically associated with the pathogenesis of allergic diseases (18,19). MCs role in parasitic infections is much less clear compared with that of eosinophils, despite considering infections as possible triggers for activation of MCs in some individuals.…”