Objectives <p>To characterize the clinical and myo-fascial histopathological features, along with long-term treatment outcomes of patients with eosinophilic fasciitis (EF).</p> Methods <p>We performed a retrospective analysis of the clinical, serological, myo-fascial pathological features, as well as the long-term follow-up outcomes of EF patients between January 2011 and August 2023 at our neuromuscular disorder (NMD) center.</p> Results <p>Seventeen patients were included, and a male predominance (12/17, 70.6%) was identified. The most common clinical manifestation was skin thickening (100%), always distal to the elbow and knee joints, occupied by limited joint mobility (12/17, 70.6%). The “prayer sign” was observed in 7 (41.2%) patients. Eosinophilia was identified in only 7 (41.2%) patients, including 6 in the blood and 3 in tissue. Anti-Ha antibody was confirmed in one patient (P17). Typical fascial edema with or without involvement of the adjacent subcutaneous tissues was exhibited on magnetic resonance imaging (MRI) in all 9 patients. The perifascicular pattern of MHC-I and/or MHC-II upregulation without MxA expression was identified in 56.3% (9/16) of the patients’ muscle specimens. Typical perifascicular atrophy was identified in 4 patients. Complete recovery was noted in 5 patients, including 4 patients treated with prednisone as monotherapy, and 1 patient treated with prednisone combined with D-penicillamine.</p> Conclusions <p>The “prayer sign” might be an important clinical feature of EF. Perifascicular upregulation of MHC-I and/or MHC-II but negative expression of MxA, with or without PFA, represents a unique pathological phenotype of EF. Most patients show favorable outcome following steroid monotherapy or in combination with immunosuppressants, underscoring the autoimmune pathogenic nature of this disease.</p>