Rheumatoid meningitis in a patient with overlap syndrome: The usefulness of anti-citrullinated peptide antibodies determination in CSF.

The article focuses on a case report of rheumatoid meningitis (RM), a rare complication of rheumatoid arthritis (RA), occurring in a 63-year-old woman with overlap syndrome (OS)—a condition involving features of multiple autoimmune connective tissue diseases including amyopathic dermatomyositis, RA, and systemic lupus erythematosus (SLE). The patient presented with stroke-like neurological symptoms, cerebrospinal fluid (CSF) lymphocytic pleocytosis, and characteristic brain MRI meningeal enhancements. Notably, anti-citrullinated peptide antibodies (ACPA), which are biomarkers for RA, were detected in both serum and CSF, suggesting a potential pathogenic role of ACPA in RM even without evidence of intrathecal synthesis. This case highlights the diagnostic value of measuring ACPA in CSF for patients with CNS disturbances and overlapping autoimmune conditions involving RA.