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Eosinophilia-Myalgia Syndrome Workup

  • Author: Thomas A Medsger, Jr, MD; Chief Editor: Herbert S Diamond, MD  more...
Updated: Jan 30, 2014

Laboratory Studies

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  • Because the presenting symptoms and physical findings in eosinophilia-myalgia syndrome (EMS) vary significantly, the workup is mainly directed toward identifying other possible causes of the patient's findings. Laboratory tests are essential in differentiating EMS from other causes of myalgia, weakness, and eosinophilia.
  • The presence of peripheral blood eosinophilia is an essential element in the diagnosis of EMS based on the CDC surveillance criteria. This finding may be missed because eosinophilia occurs early in the course of the disease and may later disappear spontaneously.
    • Even though the CDC criteria require an eosinophil count of at least 1000 cells/µL for diagnosis, the eosinophil counts observed in EMS patients are most frequently higher.
    • Eosinophil counts of 10,000-30,000 cells/µL are not unusual, and the bone marrow shows hyperplasia of eosinophil precursor cells.
  • Laboratory findings commonly observed in patients with EMS include the following:
    • Leukocytosis: White blood cell count elevations may range from mild to moderate.
    • Abnormal LFT results are common, and mild-to-moderate elevation of transaminase levels is observed in approximately 40% of patients. Frank liver failure has not been described.
    • An elevated serum creatine kinase level is uncommon, affecting only approximately 10% of patients with EMS. levels that are below normal are more common. Elevated aldolase levels are common and occur in approximately half of patients.
    • Mild-to-moderate elevation of the erythrocyte sedimentation rate (ESR) is observed in one third of patients. ESRs greater than 50 mm/h are infrequent.
    • Antinuclear antibodies with a speckled pattern in low titer are observed in approximately half of patients. The significance of this finding is uncertain.

Imaging Studies

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  • Chest radiographic results vary from normal to acute infiltrates.
  • Pleural effusion and infiltrates (diffuse or bibasilar) are seen in less than one third of patients.
  • MRI of the brain has shown subcortical infarcts, focal lesions in the deep white matter, cortical atrophy, ventricular dilatation, and both diffuse and periventricular white matter abnormalities.
  • MR spectroscopic findings are consistent with widespread inflammatory cerebrovascular disease.

Other Tests

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  • Pulmonary function testing reveals a slightly decreased diffusion capacity in up to half of patients with EMS but no evidence of restrictive lung disease.
  • Electrophysiologic studies demonstrate myopathic and neuropathic changes of varying degrees. Nerve conduction studies show mixed demyelination and a pattern of axonal degeneration.
  • Echocardiography typically shows normal left ventricular function and estimated pulmonary artery (PA) pressure less than 30 mm Hg, but pulmonary arterial hypertension is occasionally detected.


Biopsy of skin muscle and/or subcutaneous tissue


Histologic Findings

No consistent findings are observed in biopsy specimens from patients with EMS; therefore, histopathologic findings are helpful but not diagnostic.

Muscle biopsy commonly reveals inflammatory infiltrates, frequently perivascular, in the endomysium and perimysium. The inflammatory cells are predominantly lymphocytes and acid phosphatase–reactive histiocytes, with rare eosinophils. In some instances, microangiopathy is present.[11] Generalized type II myofiber atrophy and denervation atrophy are common, but myofiber necrosis and degeneration are infrequent.

Skin/fascia biopsy findings generally reveal a normal epidermis. The dermis may be normal or may have perivascular infiltrates of monocytes, eosinophils, and lymphocytes without fibrinoid necrosis. Fasciitis is indistinguishable from eosinophilic fasciitis. Findings vary from extensive infiltrates with lymphoplasmacytoid cells, eosinophils, and monocytes to diffuse fibrosis of connective tissue extending into dermis and epimysium. These findings differ from those in patients with scleroderma, who have more collagen deposition in the dermis.

Nerve biopsy shows a combination of demyelination and axonal degeneration, with epineural, perineural, and perivascular cellular infiltrates.

Contributor Information and Disclosures

Thomas A Medsger, Jr, MD Gerald P Rodnan Professor of Medicine, Director, Scleroderma Research Program, Department of Medicine, University of Pittsburgh School of Medicine

Thomas A Medsger, Jr, MD is a member of the following medical societies: American College of Rheumatology

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.

Lawrence H Brent, MD Associate Professor of Medicine, Jefferson Medical College of Thomas Jefferson University; Chair, Program Director, Department of Medicine, Division of Rheumatology, Albert Einstein Medical Center

Lawrence H Brent, MD is a member of the following medical societies: American Association for the Advancement of Science, American Association of Immunologists, American College of Physicians, American College of Rheumatology

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: Janssen<br/>Serve(d) as a speaker or a member of a speakers bureau for: Abbvie; Genentech; Pfizer; Questcor.

Chief Editor

Herbert S Diamond, MD Visiting Professor of Medicine, Division of Rheumatology, State University of New York Downstate Medical Center; Chairman Emeritus, Department of Internal Medicine, Western Pennsylvania Hospital

Herbert S Diamond, MD is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American College of Rheumatology, American Medical Association, Phi Beta Kappa

Disclosure: Nothing to disclose.

Additional Contributors

Carlos J Lozada, MD Director of Rheumatology Fellowship Training Program, Professor of Clinical Medicine, Department of Medicine, Division of Rheumatology and Immunology, University of Miami, Leonard M Miller School of Medicine

Carlos J Lozada, MD is a member of the following medical societies: American College of Physicians, American College of Rheumatology

Disclosure: Received honoraria from Pfizer for consulting; Received grant/research funds from AbbVie for other; Received honoraria from Heel for consulting.


Mohammed Mubashir Ahmed, MD Associate Professor, Department of Medicine, Division of Rheumatology, University of Toledo College of Medicine

Mohammed Mubashir Ahmed, MD is a member of the following medical societies: American College of Physicians, American College of Rheumatology, and American Federation for Medical Research

Disclosure: Nothing to disclose.

Eisha Mubashir, MD Fellow in Rheumatology, Department of Medicine, Fellow, Center of Excellence for Arthritis and Rheumatology, Louisiana State University Health Sciences Center, Shreveport

Disclosure: Nothing to disclose.

Shrilekha Sairam, MD, MBBS Fellow, Department of Internal Medicine, Division of Rheumatology, University of Texas at Galveston

Disclosure: Nothing to disclose.

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