Primary FIP1L1-PDGFR Positive Hypereosinophilic Syndrome with Unusual Rheumatic Onset
Authors: Sima Cosmin , Iosif Cristina , Busuioc Constantin , Dobrea Camelia , Predeţeanu Denisa , Coriu Daniel , Crișan Ana Manuela 
Published: July 2020

Introduction. Hypereosinophilia (HE) is defined as an absolute eosinophil count >1.5 x 109/L in the peripheral blood on two examinations separated in time by at least one month and/or pathologic confirmation of tissue HE. A hypereosinophilic syndrome (HES) is defined by the association of HE with eosinophil-mediated organ damage and/or dysfunction if other potential causes of them have been excluded.

Case report. We report a case of a 52-year-old woman admitted to Rheumatology Department for diffuse, highly intense (10/10) myalgia, associated with paravertebral, upper and lower limbs muscular edema and stiffness, having the onset of symptoms for about 4 months. During rheumatological evaluation, the patient developed posterior cervical diffuse pain with brachial irradiation associated with severe functional impotence reason for which it was indicated MRI of cervical spine. The blood count showed leucocytosis with hypereosinophilia. No evidence of Raynaud’s phenomenon, cutaneous and muscular sclerosis or visceral involvement. All muscular groups and deep fascia appeared affected on the whole-body MRI and the findings were suggestive for Shulman’s eosinophilic fasciitis or eosinophilic myopahty. All autoimmune, parasitic and allergic causes for myopathy were ruled out. Muscle tissue biopsy revealed high eosinophilic infiltrate predominantly in the deep muscular fascia, in the striated muscles and in the superficial dermis.

The patient received methyl-prednisolone pulse-therapy with a low-maintenance dose of prednisone which showed clinical improvement and normalized peripheral blood eosinophilia. A hematologic evaluation revealed high percentage of bone marrow eosinophil count which harbored FIP1L1-PDGFR alpha mutation and data was suggestive for the diagnosis of myeloproliferative variant of HES syndrome along with Shulman’s eosinophilic fasciitis for which Imatinib treatment was indicated.

Conclusion. The particularity of this case consists in the diagnosis of a myeloproliferative variant of HES with atypical presentation as a Shulman’s eosinophilic fasciitis, a rheumatological condition. Even though initial symptoms were suggestive for a myopathy, it was difficult to establish the positive diagnosis without any obvious paraclinical data. Further investigations such as MRI and muscle biopsy were conclusive for the diagnosis of Shulman’s eosinophilic fasciitis and clinical improvement was observed after corticosteroid treatment. Considering that after 4 months of evolution of the disease the patient did not present any atrophic lesions of the affected muscles and skin characteristic for Shulman’s eosinophilic fasciitis the patient was referred to Hematology Department with the diagnosis of HES. Advanced exams established the hematological condition as primary FIP1L1-PDGFR positive HES which could benefit from tyrosine-kinase inhibitors treatment (Imatinib) known to induce in this situation improved clinical and paraclinical status.