Eosinophilic fasciitis illustrated by [18F]FDG PET/CT

Eosinophilic fasciitis is a rare sclerodermiform disease characterized by upper and lower limb edema. We present the case of a 71-year old woman currently hospitalized for painful lower limb edema. Laboratory tests reveal moderate eosinophilia (0.8 G/L) and an inflammatory syndrome. Abdominopelvic ultrasound reveals no abnormalities. In light of the unexplained inflammatory syndrome, a [¹⁸F]FDG PET-CT scan currently shows intense hypermetabolism of the fasciae in the lower and upper limbs. Following an MRI, a biopsy is performed, and the anatomopathology currently confirms eosinophilic fasciitis. The frank hypermetabolism of the fascia in the upper and lower limbs, combined with the patient's current clinical history (onset of painful edema in the extremities, hypereosinophilia, and unexplained inflammatory syndrome) suggests eosinophilic fasciitis or Shulman's fasciitis. The etiology and the pathogenesis of Shulman's fasciitis are not well understood, but an autoimmune cause is probable. It is a rare pathology described by Shulman in 1974, characterized by symmetrical full-circumference sclerotic lesions with painful edema in all four limbs with eosinophilia. Edema is the most common initial symptom. The gold standard for confirming the diagnosis involves biopsy from the skin to the fascia. Imaging examinations aid in guiding the areas to be biopsied. MRI is typically used, but [¹⁸F]FDG-PET/CT also plays an important role in ruling out a paraneoplastic origin for these inflammatory symptoms. Anatomopathological analysis of this skin sample shows fascial thickening with inflammatory cell infiltration. Therapeutic options include high-dose corticosteroids, other immunosuppressive drugs like Methotrexate, and physiotherapy.