What causes eosinophilic fasciitis (EF)?

Updated: Dec 24, 2020
  • Author: Peter M Henning, DO; Chief Editor: Herbert S Diamond, MD  more...
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The etiology of eosinophilic fasciitis is unknown. Its clinical manifestations are the result of an inflammatory response in the affected tissues. As explained above, the current understanding of eosinophilic fasciitis relies on a relatively few case series and case reports. As such, many etiologic factors have been suggested with varying degrees of supporting evidence. Any of these factors, alone or in combination, may possibly initiate this inflammatory response.

Several possible triggers have been reported with some consistency. A preceding history of vigorous exercise or trauma has been reported in 30%-50% of patients. [14, 15]  Multiple drugs have also been implicated, including simvastatin, atorvastatin, and phenytoin. [16, 17, 18]  A number of cases of eosinophilic fascitis following treatment with immunne checkpoint inhibitors atezolizumab, nivolumab and pembrolizumab have been reported.

Several cases have demonstrated positive Borrelia serologies. The significance of this finding continues to be debated. Spirochetes were visualized by silver stain in 4 patients in one study. [19]  These findings have not been repeated. It has been suggested that positive serology for Borrelia represents an epiphenomenon among cases from Borrelia-endemic areas and is insufficient evidence of infection and therefore does not support a causal association. [20]

Eosinophilic fasciitis shares clinical similarities, as well as key differences, with eosinophilia-myalgia syndrome. Some studies have suggested an association between l-tryptophan ingestion and eosinophilic fasciitis. [21, 22]  Despite this, there is no consistent association between l-tryptophan or other dietary exposure and eosinophilic fasciitis. As evidence, l-tryptophan use was significantly associated with dyspnea, an uncommon finding in eosinophilic fasciitis cases. In another instance, a patient with eosinophilic fasciitis had used l-tryptophan for several years but had started a formal exercise program 2 weeks prior to disease onset.

Multiple additional etiologic triggers have been suggested by single or infrequent case reports.

As with etiology, eosinophilic fasciitis has been associated with several diseases. [23]

Hematologic diseases have been consistently reported and are supported by large case series and case reports. [14, 15, 24]  The spectrum of associated hematologic disease is broad and includes aplastic and hemolytic anemia, thrombocytopenia, myeloproliferative disorders, myelodysplastic disorders, lymphoma, leukemia, monoclonal gammopathy of undetermined significance (MGUS), and multiple myeloma. [24, 25, 26]

An association with thyroid disease has been reported in several cases. [27]  Eosinophilic fasciitis has rarely been linked to solid-organ tumors and primary biliary cirrhosis, in addition to several other diseases. These disease associations may suggest a shared pathophysiology of cellular dysregulation and/or autoimmunity.

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