Laboratory abnormalities are often limited to the finding of peripheral eosinophilia. The eosinophilia is typically present early in the disease course, but may not be persistent and often the presence or degree of peripheral eosinophilia does not correlate with the severity of the fasciitis. Elevated serologic inflammatory markers (e.g., ESR and CRP) and polyclonal hypergammaglobulinemia can be seen, and—in contrast to SSc patients—these patients typically are autoantibody negative.
The diagnosis of DFE usually requires a full-thickness en bloc biopsy of the affected area—deep enough to include skin, fascia and muscle. The fascia will characteristically show features of both fibrosis and inflammation; with a plasmalymphocytic and prominent eosinophilic cellular infiltration.
The clinical course of DFE varies from a self-limited process that improves within a few years to one of chronic-active or recurrent fasciitis. DFE is typically treated with immunosuppressive medications that include corticosteroids followed by maintenance therapy, with corticosteroid-sparing agents, such as methotrexate.5,7,8
Eosinophilia Myalgia Syndrome & Toxic Oil Syndrome
Two historic entities, eosinophilia myalgia syndrome (EMS) and toxic oil syndrome (TOS), presented with similar clinical and histopathologic findings as DFE. Each occurred in epidemic form after specific environmental exposures. TOS occurred in Spain in 1981 and affected ~20,000 people. It was related to the ingestion of rapeseed oil denatured with the chemical, aniline, which was present in a specific cooking oil.5
When evaluating a patient with eosinophilia, it’s important to review the patient’s history & exclude the most common causes of eosinophilia—medications & infectious causes.
EMS occurred in epidemic form in 1989 in the U.S., affected ~1,500 people and was associated with ingestion of contaminated forms of L-tryptophan.5
These eosinophilic disorders are exceedingly rare, but highlight the potential for novel causes of eosinophilia to emerge.
Hypereosinophilic Syndromes
The hypereosinophilic syndromes are a heterogeneous group of diseases characterized by persistent eosinophilia of >1,500 eosinophils/mm3 in association with end-organ damage or dysfunction in the absence of secondary causes of eosinophilia.9
The predominant hypereosinophilic syndrome subtypes are the myeloproliferative and lymphocytic variants. Familial, undefined and overlap syndromes with incomplete criteria are less common subtypes. The myeloproliferative variant may be divided into three subgroups: 1) chronic eosinophilic leukemia with demonstrable cytogenetic abnormalities and/or blasts on peripheral smear; 2) the PDGFRA-associated hypereosinophilic syndrome, attributed to a constitutively activated tyrosine kinase fusion protein (Fip1L1-PDGFRα) due to a chromosomal deletion on 4q12; this variant is often responsive to imatinib; and 3) the FIP1-negative variant associated with clonal eosinophilia and associated with dysplastic peripheral eosinophils, increased serum vitamin-B12, increased tryptase, anemia, thrombocytopenia, splenomegaly, bone marrow cellularity >80%, spindle-shaped mast cells and myelofibrosis.10
