hematology and oncology
Eosinophilia
Evaluation of Eosinophilia
Numerous conditions can cause eosinophilia. Common causes (eg, allergic, infectious, or neoplastic disorders) should be considered first, but even they are often difficult to identify, so a thorough history and physical examination are always required. The questions most likely to be helpful pertain to the following: Travel (suggesting possible parasite exposure) Allergies Medication use Use of herbal products and dietary supplements, including L-tryptophan Systemic symptoms (eg, fever, weight loss, myalgias, arthralgias, rashes, lymphadenopathy) Systemic symptoms suggest that a minor allergic or medication cause is less likely, and a detailed evaluation for an infectious, neoplastic, systemic rheumatic disease, or other systemic disorder should be done. Other important parts of the history include family history of blood disorders and a complete review of systems, including symptoms of allergies and pulmonary, cardiac, gastrointestinal (GI), and neurologic dysfunction. A general physical examination should focus on the heart, skin, and neurologic and pulmonary systems. Certain physical findings may suggest causes or associated disorders. Examples include rash (allergic, dermatologic, or vasculitic disorders), abnormal lung findings (asthma, lung infections, or syndromes of pulmonary infiltration with eosinophilia), and generalized lymphadenopathy or splenomegaly (myeloproliferative disorders or cancer). Eosinophilia is typically recognized when a complete blood count (CBC) is done for other reasons. Additional testing often includes the following ( Evaluation reference ): Stool ova and parasite testing Other tests to detect organ damage or for specific causes based on clinical findings In general, if a medication or allergic cause is not suspected based on clinical findings, 3 stool specimens should be examined for ova and parasites; however, negative findings do not rule out a parasitic cause (eg, Trichinosis requires a muscle biopsy; Other specific diagnostic tests are determined by the clinical findings (particularly travel history) and may include chest x-ray, urinalysis, liver and kidney tests, and serologic tests for parasitic and systemic rheumatic diseases. If patients have generalized lymphadenopathy, splenomegaly, or systemic symptoms, blood tests are done. An elevated serum vitamin B12 level or abnormalities on the peripheral blood smear suggest an underlying Overview of Myeloproliferative Neoplasms , and a bone marrow aspirate and biopsy with cytogenetic studies may be helpful. If a routine evaluation does not reveal a cause, tests are done to detect organ damage. Testing can include some of the tests previously mentioned as well as lactate dehydrogenase (LDH) and liver tests (suggesting liver damage or possibly a Overview of Myeloproliferative Neoplasms ). Echocardiography, serum troponin levels, and pulmonary function tests are performed when 1.Klion AD: Approach to the patient with suspected hypereosinophilic syndrome.Hematology Am Soc Hematol Educ Program2022; 2022(1):47-54. doi: 10.1182/hematology.2022000367 