Eosinophilia: A Diagnostic Evaluation Guide for Rheumatologists

If hypereosinophilic syndromes are being strongly considered in the evaluation of a patient with eosinophilia, bone marrow biopsy can be a valuable addition to the diagnostic workup. Corticosteroids and other immunosuppressive agents are the mainstay of treatment.

IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a disorder associated with peripheral eosinophilia. IgG4-RD is a fibro-inflammatory condition characterized by dense lymphoplasmacytic infiltrative lesions composed largely of IgG4-positive plasma cells, and areas of fibrosis, and is frequently associated with elevated serum IgG4 levels.^11,12 IgG4-RD can affect nearly every organ system, and patients with this disease have a predilection for forming fibro-inflammatory mass lesions within affected organs.^11,12 IgG4-RD can be associated with allergic or atopic diseases. Thus, patients with IgG4-RD often have longstanding histories of allergic rhinitis or asthma, and many have elevated serum levels of IgE. Peripheral eosinophilia may be seen with IgG4-RD and moderate eosinophilic infiltration is commonly identified on histopathologic samples of the fibro-inflammatory lesions.^11,12

Summary, Conclusion & Future Directions

The presence of elevated levels of blood and/or tissue eosinophils is common to all of the conditions discussed in this focused review. Although the eosinophil plays an important role in each of these syndromes, there are important clinical and pathologic differences, as well as differences in prognosis and treatment paradigms. Recognition of these entities by the treating rheumatologist and early intervention with appropriate treatment can prevent significant morbidity and prevent eosinophilic organ damage. Although the cornerstone of treatment for each of these therapies generally involves systemic corticosteroids or the addition of traditional corticosteroid-sparing agents, novel therapies are emerging that target cytokines, such as IL-4 or IL-5, and provide hope to the many patients affected by eosinophilia.

Praveen Akuthota, MD, works in the Division of Pulmonary, Critical Care, & Sleep Medicine at Beth Israel Deaconess Medical Center in Boston and is an assistant professor of medicine at Harvard Medical School.

Aryeh Fischer, MD, is associate professor of medicine in the Department of Medicine at the University of Colorado School of Medicine in Denver.

Michael E. Wechsler, MD, is a professor of medicine and director of the Asthma Program in the Department of Medicine at National Jewish Health in Denver.

Disclosure Statement

The corresponding author, Dr. Wechsler, has received research support from a joint-sponsored NIH and GlaxoSmithKline study of mepolizumab for EGPA. He has also received honoraria for consulting, advisory boards and lectures from Teva, AstraZeneca, Boston Scientific, Novartis, Sanofi, Vectura, Sunovion, Regeneron and Ambit Bioscience.

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