Eosinophilic disease

Eosinophilia is defined as an increase of circulating eosinophils >500 /mm³. Based on the counts, eosinophilia can be divided into different categories: mild (500 to 1500/mm³), moderate (1500 to 5000/mm³), and severe (> 5000/mm³). Hypereosinophilic syndrome is defined as an absolute eosinophil count greater than 1500/mm³ on two occasions at least one month apart or marked tissue eosinophilia.

Eosinophilia can be primary or secondary;

Primary causes

• Chronic eosinophilic leukaemia
• Myeloid and lymphoid neoplasms with rearrangements of PDGFRA, PDGFRAB, or FGFR1 genes
• Hereditary eosinophilia
• Idiopathic hypereosinophilic syndrome

Secondary causes:

• Parasitic infestations: ancylostomiasis, ascariasis, cysticercosis, echinococcosis (hydatid cyst), schistosomiasis, strongyloidiasis, trichinellosis, visceral larva migrans (toxocariasis)
• Fungal and bacterial infections: bronchopulmonary aspergillosis, chronic tuberculosis (occasionally), coccidioidomycosis, disseminated histoplasmosis, scarlet fever
• Allergic disorders: bronchial asthma, hay fever, Stevens-Johnson syndrome, drug, and food allergic reactions, DRESS syndrome
• Skin diseases: Atopic dermatitis, eczema, pemphigus, Mycosis fungoides, Sezary syndrome
• Graft versus host reaction
• Connective tissue disease: Churg-Strauss syndrome, eosinophilic myalgia syndrome
• Miscellaneous: reactive pulmonary eosinophilia, tropical eosinophilia, pancreatitis, eosinophilic gastroenteritis

Reference

1. Klion AD. Eosinophilia: a pragmatic approach to diagnosis and treatment. Hematology Am Soc Hematol Educ Program. 2015;2015:92-7