Favorable clinical outcomes of biologic and targeted therapies in refractory eosinophilic fasciitis: a case-based systematic review.

Eosinophilic fasciitis (EF) is a rare autoimmune disease characterized by fascial inflammation, skin induration, eosinophilia, and progressive functional impairment. Although glucocorticosteroids (GCs) remain the first-line therapy, some patients develop refractory or steroid-dependent disease, highlighting the need for alternative treatment strategies. This case-based review summarizes current evidence on biologic and targeted therapies in severe EF and presents a case of successful treatment with tocilizumab (TCZ). A systematic review of PubMed, Scopus, and Web of Science databases identified 35 eligible articles published between 2008 and 2026. Qualitative synthesis included 49 patients treated with biologic or targeted agents, most commonly rituximab (n = 14), tocilizumab (n = 9), infliximab (n = 7), and mepolizumab (n = 5). Partial or complete response was achieved in 47 of 49 (96%) patients across all treatment groups. Biologic therapy was associated with a pronounced steroid-sparing effect, enabling GCs dose reduction or complete withdrawal in the majority of refractory patients. Furthermore, we describe a 28-year-old man with progressive, treatment-resistant EF who failed to respond adequately to GCs and methotrexate. Following initiation of weekly subcutaneous TCZ, the patient showed marked clinical, laboratory, and radiological improvement, with normalization of inflammatory markers, regression of fascial edema on MRI, and substantial functional recovery. Available case-based evidence suggests that biologic and targeted therapies, including IL-6 inhibition, may be promising options in selected patients with severe, refractory, or GC-dependent EF. However, considering the high risk of publication bias and reliance on case reports, prospective multicenter studies are required to establish standardized treatment recommendations.