Immune checkpoint inhibitor-associated eosinophilic fasciitis: a systematic review of reported cases.

BACKGROUND

Eosinophilic Fasciitis (EF) is a rare immune-mediated fibrosing disorder of the fascia. Immune Checkpoint Inhibitors (ICIs) have transformed oncologic therapy but may precipitate immune-related Adverse Events (irAEs), including dermatologic and rheumatologic manifestations. ICI-associated EF has been increasingly reported, yet remains poorly characterized.

OBJECTIVE

To systematically summarize the clinical features, diagnostic approaches, management strategies, and outcomes of ICI-associated EF.

METHODS

A systematic review was conducted in accordance with PRISMA 2020. PubMed/MEDLINE, EMBASE, and Web of Science were searched from inception through January 2026. Eligible studies were case reports, case series, or observational studies describing adult cancer patients who developed EF temporally associated with ICI therapy. Two reviewers independently screened studies, extracted data, and assessed methodological quality using Joanna Briggs Institute tools.

RESULTS

Among 148 records identified, 93 remained after removal of 55 duplicates; 28 full-text articles were assessed and 18 met inclusion criteria, representing 22 unique patients. Nivolumab and pembrolizumab were the most frequently implicated agents. EF onset ranged from several weeks to months after ICI initiation. The most commonly affected regions were the extremities. Diagnosis was confirmed by histopathology and/or imaging in most cases. Systemic corticosteroids were the main treatment, with additional immunosuppressive agents used in selected patients. Most cases showed partial or complete clinical improvement.

STUDY LIMITATIONS: Evidence is limited to case reports and small case series, with heterogeneous reporting, precluding incidence estimation and limiting generalizability.

CONCLUSIONS

ICI-associated EF is a rare but clinically relevant irAE with dermatologic and connective tissue involvement. Early recognition and multidisciplinary management are essential to prevent long-term morbidity.