Eosinophilia is commonly due to allergic diseases, parasitic infection, drug reactions, or skin disease. Rare causes include malignancy, gastrointestinal disorders, connective tissue diseases, immune deficiency states, hereditary eosinophilia, and cyclical eosinophilia with angioedema.[3]Montgomery ND, Dunphy CH, Mooberry M, et al. Diagnostic complexities of eosinophilia. Arch Pathol Lab Med. 2013 Feb;137(2):259-69.
http://www.archivesofpathology.org/doi/full/10.5858/arpa.2011-0597-RA
http://www.ncbi.nlm.nih.gov/pubmed/23368869?tool=bestpractice.com
[4]Larsen RL, Savage NM. How I investigate eosinophilia. Int J Lab Hematol. 2019 Apr;41(2):153-61.
https://onlinelibrary.wiley.com/doi/full/10.1111/ijlh.12955
http://www.ncbi.nlm.nih.gov/pubmed/30499630?tool=bestpractice.com
Parasitic infestations
Many parasitic infestations can result in eosinophilia, particularly strongyloidiasis, schistosomiasis, filariasis, trichinellosis, toxocariasis, fasciolopsiasis, muscular sarcocystosis, Cystoisospora belli (formerly Isospora belli) infection, anisakiasis, and loiasis.[5]O'Connell EM, Nutman TB. Eosinophilia in infectious diseases. Immunol Allergy Clin North Am. 2015 Aug;35(3):493-522.
http://www.ncbi.nlm.nih.gov/pubmed/26209897?tool=bestpractice.com
Allergic diseases
Allergic diseases, such as asthma or allergic rhinitis, are usually apparent from the history.
Drug reactions
Hypersensitivity to many drugs, including carbamazepine, allopurinol, sulfonamides, penicillin, phenytoin, and gold, may cause eosinophilia.
Skin diseases
Possible skin diseases are pemphigus, bullous pemphigoid, and pemphigoid gestationis.
Immune deficiency syndromes
Possible etiologies include Wiskott-Aldrich syndrome, Job syndrome, hyperimmunoglobulin E syndrome, severe combined immune deficiency due to adenosine deaminase deficiency, and Omenn syndrome.[6]Grimbacher B, Holland SM, Gallin JI, et al. Hyper-IgE syndrome with recurrent infections--an autosomal dominant multisystem disorder. N Engl J Med. 1999 Mar 4;340(9):692-702.
http://www.nejm.org/doi/full/10.1056/NEJM199903043400904#t=article
http://www.ncbi.nlm.nih.gov/pubmed/10053178?tool=bestpractice.com
[7]Zhang Q, Davis JC, Lamborn IT, et al. Combined immunodeficiency associated with DOCK8 mutations. N Engl J Med. 2009 Nov 19;361(21):2046-55.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2965730
http://www.ncbi.nlm.nih.gov/pubmed/19776401?tool=bestpractice.com
[8]Williams KW, Milner JD, Freeman AF. Eosinophilia associated with disorders of immune deficiency or immune dysregulation. Immunol Allergy Clin North Am. 2015 Aug;35(3):523-44.
http://www.ncbi.nlm.nih.gov/pubmed/26209898?tool=bestpractice.com
Immune dysregulation
The possible etiologies are: immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome; autoimmune lymphoproliferative syndrome (ALPS); Loeys-Dietz syndrome; Comel-Netherton syndrome; and severe dermatitis, multiple allergies, and metabolic wasting (SAM) syndrome.[8]Williams KW, Milner JD, Freeman AF. Eosinophilia associated with disorders of immune deficiency or immune dysregulation. Immunol Allergy Clin North Am. 2015 Aug;35(3):523-44.
http://www.ncbi.nlm.nih.gov/pubmed/26209898?tool=bestpractice.com