Eosinophilic Fasciitis With Overlap Connective Tissue Disease: A Diagnostic Challenge in Progressive Skin Fibrosis.

Eosinophilic fasciitis (EF) is a rare connective tissue disorder characterized by inflammation and fibrosis of the deep fascia and adjacent subcutaneous tissue. Because its clinical presentation may resemble systemic sclerosis (SSc), diagnosis can be delayed, particularly in patients with an established autoimmune disease. We report a 48-year-old woman with undifferentiated connective tissue disease (UCTD), inflammatory arthritis, and Sjögren's disease overlap syndrome who developed progressive skin thickening and loss of range of motion despite treatment for inflammatory arthritis. Although EF typically spares the fingers, this patient developed marked finger and hand tightness with inability to make a fist, resulting in an atypical sclerodactyly-like presentation that initially raised concern for SSc. However, the absence of Raynaud phenomenon, normal nailfold capillaroscopy, repeatedly negative SSc-specific antibodies, historical peripheral eosinophilia, and magnetic resonance imaging (MRI) demonstrating fascial thickening and enhancement supported a diagnosis of EF. A full-thickness skin-to-fascia biopsy was deferred because of prior glucocorticoid and immunosuppressive exposure and concern for impaired wound healing. The patient was treated with high-dose prednisone followed by a taper, together with mycophenolate and tocilizumab. Over the subsequent six months, she had improved hand closure, grip strength, and mobility, with stable skin findings at 18 months. This case highlights that EF can occasionally involve the fingers and mimic SSc, and that reviewing the overall clinical phenotype and historical laboratory data is important when the presentation is atypical.