What are the causes of hyper eosinophilia?

From the Guidelines

Hypereosinophilia is primarily caused by secondary (reactive) conditions, with allergic disorders being the most common cause, occurring in about 80% of cases, followed by parasitic infections, particularly strongyloidiasis, as stated in the most recent and highest quality study 1. The causes of hyper eosinophilia can be categorized into primary and secondary conditions. Primary causes include hematologic disorders, while secondary causes are more common and encompass a wide range of conditions.

• Allergic reactions, such as those seen in asthma, food allergy, atopic dermatitis, and drug reactions, are the most frequent secondary causes of hyper eosinophilia, as noted in 1.
• Parasitic infections, including helminth infections like strongyloidiasis, ascariasis, and schistosomiasis, are also significant secondary causes, with strongyloidiasis being the most common parasitic infection, as mentioned in 1.
• Other secondary causes include autoimmune disorders, such as eosinophilic granulomatosis with polyangiitis, and certain solid tumors, as well as pulmonary conditions like eosinophilic pneumonia, as discussed in 1.
• Immunodeficiency syndromes, such as hyperimmunoglobulin E syndrome, Omenn syndrome, and Wiskott-Aldrich syndrome, can also be associated with hyper eosinophilia, as stated in 1.
• It is essential to accurately diagnose the underlying cause of hyper eosinophilia to establish an appropriate treatment plan, taking into account histopathologic, clinical, laboratory, cytogenetic, and molecular criteria, as emphasized in 1.

From the Research

Causes of Hyper Eosinophilia

The causes of hyper eosinophilia can be broadly categorized into several groups, including:

• Allergic reactions, such as those caused by drugs or other substances 2
• Infectious diseases, including parasitic infections 2, 3
• Malignant diseases, such as myeloproliferative disorders 2
• Autoimmune diseases, including eosinophilic granulomatosis with polyangiitis 2
• Primary eosinophilic disorders, such as hypereosinophilic syndrome (HES) 4, 5
• Idiopathic hypereosinophilic syndrome (HES), which is a diagnosis of exclusion 4

Secondary Causes of Eosinophilia

Secondary causes of eosinophilia must be excluded before a diagnosis of primary eosinophilia can be made. These secondary causes include:

• Parasitic infections 2, 3
• Allergic reactions 2
• Other causes of tissue eosinophilia 2

Disease Classification

The World Health Organization endorses a semi-molecular classification scheme of disease subtypes, including:

• Myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB, or FGFR1 or with PCM1-JAK2 4
• Myeloproliferative neoplasm subtype, "chronic eosinophilic leukemia, not otherwise specified" (CEL, NOS) 4
• Lymphocyte-variant hypereosinophilia (HE) 4
• Idiopathic hypereosinophilic syndrome (HES) 4, 5