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Hypereosinophilic Syndrome Workup

  • Author: Venkata Anuradha Samavedi, MBBS, MD; Chief Editor: Emmanuel C Besa, MD  more...
Updated: Feb 23, 2016

Approach Considerations

After a thorough workup has excluded causes for secondary eosinophilia, a diagnosis of hypereosinophilic syndrome is suspected in cases of persistent eosinophilia. Any such patients with a documented absolute eosinophil count (AEC) greater than 1500/µL on at least two occasions should be evaluated for hypereosinophilic syndrome, regardless of the presence of symptoms.

A complete blood cell (CBC) count and peripheral smear is warranted.[23]

Serum tryptase levels are elevated in FIP1LI-PDGFRA –positive hypereosinophilic syndrome, as well as systemic mastocytosis with chronic eosinophilic leukemia (SM-CEL). Hence, in such cases, the workup should include the following:

  • Bone marrow tryptase levels
  • Immunophenotyping of mast cells – Mast cells in systemic mastocytosis coexpress CD117 with CD2 and/or CD25
  • Molecular genetic studies to detect FIP1L1-PDGFRA mutation (which is present in hypereosinophilic syndrome and systemic mastocytosis) and C-KIT mutation (which is present in systemic mastocytosis) are done to determine imatinib sensitivity

Bone marrow biopsy should be evaluated for the following :

  • Morphologic examinations to look for features of myeloproliferative disorders (MPDs) and to look for dense aggregates of mast cells (greater than 15 cells) in systemic mastocytosis
  • Special stains should include reticulin stain for myelofibrosis and tryptase staining for mast cells when serum tryptase levels are elevated
  • Cytogenetics: Most patients with hypereosinophilic syndrome have normal karyotypes; in those who have cytogenetic changes, the changes may vary from aneuploidy to Philadelphia chromosome
  • Molecular genetic studies: FIP1L1/PDGFRA should be evaluated in all patients with increased tryptase levels; this mutation is present in both hypereosinophilic syndrome and systemic mastocytosis; C-KIT mutation should also be evaluated in patients with increased tryptase levels

Human leukocyte antigen (HLA) typing should be done early in the course of hypereosinophilic syndrome for patients with aggressive disease, cytogenetic aberration, or the FIPL1/PDGFRA fusion gene.

Other studies include the following:

  • T-cell immunophenotyping
  • T-cell receptor gene rearrangement
  • Interleukin-5 (IL-5) levels
  • Computed tomography (CT) scanning of the chest, abdomen, and pelvis to look for lymphadenopathy and splenomegaly

Initial evaluation of suspected hypereosinophilic syndrome should include tests to look for any evidence of end-organ damage, as follows:

  • Electrocardiography (ECG)
  • Echocardiography
  • Troponin levels: Increased levels indicate the presence of cardiomyopathy and predict the onset of cardiogenic shock due to imatinib therapy.
  • Pulmonary function tests
  • Tissue biopsy may be required in symptomatic patients, but is not always essential

Imaging Studies

Echocardiography is helpful in the initial evaluation and monitoring of cardiac disease in patients suspected with hypereosinophilic syndrome.[24] Intracardiac thrombi may be detected, as well as the fibrosis that appears not only as areas of increased echogenicity but often as posterior mitral valve leaflet thickening. Because the papillary muscles are often involved in hypereosinophilic syndrome, mitral and tricuspid dysfunction may also be detected by echocardiography.

CT scanning of the chest, abdomen, and pelvis is done to look for lymphadenopathy and splenomegaly.


Histologic Findings

Eosinophil infiltrates are present in affected tissues in patients with hypereosinophilic syndrome. Cutaneous histologic features vary with the pattern of presentation. In patients with papular or nodular lesions, perivascular mixed cellular infiltrates (eosinophils and other cell types) are present. However, vasculitis is not present.


Blood Studies

Results of hematologic studies in patients with hypereosinophilic syndrome are as follows:

  • Eosinophilia is present (>1500 cells/µL)
  • The overall neutrophil count may be normal, but it is often elevated in hypereosinophilic syndrome; many patients have absolute neutrophilia
  • Approximately 50% of the patients with hypereosinophilic syndrome are anemic at presentation, often because of anemia of chronic disease
  • Platelet counts are most often normal, but may be elevated
  • Eosinophils in the peripheral blood are mostly mature forms; immature eosinophilic precursors are rare in the peripheral blood.
  • Morphologic abnormalities that have been described include nuclear hypersegmentation, hypogranularity, and hypergranularity
  • Cases of hypereosinophilic syndrome with features of myeloproliferative disorder (MPD) show circulating leukocyte precursor anemia and thrombocytopenia or thrombocytosis; teardrops and nucleated red blood cells may be seen
  • A National Institute of Health series indicated that the presence of eosinophils with vacuolization and hypogranularity is more commonly associated with cardiac disease. [25]
  • Leukocytosis in excess of 90,000/µL carries a bad prognosis

Other blood study results are as follows:

  • Increased serum tryptase level suggests a FIP1L1-PDGFRA mutation; always rule out C-KIT mutation, which is characteristic of systemic mastocytosis whenever serum tryptase is elevated, because disease from the most common form of C-KIT mutation in systemic mastocytosis, Asp 816 to Val, is not responsive to imatinib treatment
  • Interleukin-5 (IL-5 ) levels are elevated in cases of hypereosinophilic syndrome that are associated with clonal T-cell disease; interferon alpha should be considered in such cases due to its down-regulating effects on IL-5 production by T-helper 2 (TH2) cells
  • Immunoglobulin E (IgE) levels may be elevated, and hypergammaglobulinemia is common; increased IgE levels have prognostic significance, as these patients have a lower risk of developing hypereosinophilic syndrome–associated cardiovascular disease and respond well to steroid therapy
  • Serum vitamin B-12 levels may be elevated in the presence of associated myeloproliferative features


An endocardial biopsy may be performed via cardiac catheterization if any question about the diagnosis of hypereosinophilic syndrome exists.[26]

Perform bone marrow aspiration and biopsy, and submit samples for cytogenetic studies. Occasionally, the findings may suggest an atypical presentation of chronic myelogenous leukemia. Cytogenetic abnormalities or the presence of a myeloproliferative picture in the bone marrow may be indicative of more aggressive disease.

If cutaneous involvement is present, skin biopsies may be performed to rule out other diagnoses that have similar skin presentations, such as the following:

Contributor Information and Disclosures

Venkata Anuradha Samavedi, MBBS, MD Internist in Houston, TX

Disclosure: Nothing to disclose.


Paul Schick, MD Emeritus Professor, Department of Internal Medicine, Jefferson Medical College of Thomas Jefferson University; Research Professor, Department of Internal Medicine, Drexel University College of Medicine; Adjunct Professor of Medicine, Lankenau Hospital

Paul Schick, MD is a member of the following medical societies: American College of Physicians, American Society of Hematology

Disclosure: Nothing to disclose.

Ronald A Sacher, MB, BCh, FRCPC, DTM&H Professor, Internal Medicine and Pathology, Director, Hoxworth Blood Center, University of Cincinnati Academic Health Center

Ronald A Sacher, MB, BCh, FRCPC, DTM&H is a member of the following medical societies: American Association for the Advancement of Science, American Association of Blood Banks, American Society for Clinical Pathology, American Society of Hematology, College of American Pathologists, International Society on Thrombosis and Haemostasis, Royal College of Physicians and Surgeons of Canada, American Clinical and Climatological Association, International Society of Blood Transfusion

Disclosure: Serve(d) as a speaker or a member of a speakers bureau for: GSK Pharmaceuticals,Alexion,Johnson & Johnson Talecris,,Grifols<br/>Received honoraria from all the above companies for speaking and teaching.

Vincent E Herrin, MD, FACP Professor of Medicine, Division of Hematology and Medical Oncology, Director, Medicine Residency Program, University of Mississippi School of Medicine

Vincent E Herrin, MD, FACP is a member of the following medical societies: American College of Physicians, American College of Physicians-American Society of Internal Medicine, American Society of Clinical Oncology, Southern Society for Clinical Investigation, American Society of Hematology

Disclosure: Nothing to disclose.

Joe C Files, MD Director, Division of Hematology, Associate Chairman, Professor, Department of Internal Medicine, University of Mississippi Medical Center

Joe C Files, MD is a member of the following medical societies: American Association for the Advancement of Science, American Association for Cancer Education, American College of Physicians, American Federation for Medical Research, American Heart Association, American Medical Association, American Society of Human Genetics, Mississippi State Medical Association, New York Academy of Sciences, Southern Medical Association

Disclosure: Nothing to disclose.

Youwen Zhou, MD, PhD, FRCPC Associate Professor, Department of Dermatology and Skin Science, University of British Columbia Faculty of Medicine; Director, Hyperhidrosis Specialty Clinic, Co-Director, Psoriasis and Phototherapy Centre, Consulting Physician, Department of Dermatology, Vancouver General Hospital; Co-Director, Vitiligo and Pigmentation Clinic, Oncologist Consultant, Skin Tumor Program, BC Cancer Agency

Youwen Zhou, MD, PhD, FRCPC is a member of the following medical societies: American Academy of Dermatology

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Emmanuel C Besa, MD Professor Emeritus, Department of Medicine, Division of Hematologic Malignancies and Hematopoietic Stem Cell Transplantation, Kimmel Cancer Center, Jefferson Medical College of Thomas Jefferson University

Emmanuel C Besa, MD is a member of the following medical societies: American Association for Cancer Education, American Society of Clinical Oncology, American College of Clinical Pharmacology, American Federation for Medical Research, American Society of Hematology, New York Academy of Sciences

Disclosure: Nothing to disclose.

Additional Contributors

Antoni Ribas, MD Assistant Professor of Medicine, Division of Hematology-Oncology, University of California at Los Angeles Medical Center

Disclosure: Nothing to disclose.

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Indurated edematous plaques of hypereosinophilic syndrome on a patient's legs.
Erythroderma in a patient with hypereosinophilic syndrome.
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