[Rheumatoid meningitis without arthritis presenting as widespread symmetrical high-‍intensity lesions along cerebral sulci on diffusion-weighted MRI: a case report].

A 52-year-old woman presented with the subacute onset of pantalgia, fever and consciousness disturbance. MRI revealed widespread symmetrical high-intensity areas along the sulci in both cerebral hemispheres on diffusion-weighted imaging (DWI). Rheumatoid meningitis was suspected based on elevated levels of anti-cyclic citrullinated peptide antibodies (ACPA) in both serum and cerebrospinal fluid (CSF), as well as an elevated ACPA index. Brain biopsy revealed marked infiltration of inflammatory cells in the subarachnoid space, confirming the diagnosis of rheumatoid meningitis. The patient fully recovered after receiving six courses of steroid pulse therapy, followed by postremission therapy. Diagnosing cases without arthritis can be challenging, but testing for ACPA and evaluating the ACPA index can be useful for both diagnosis and assessing therapeutic efficacy in cases of suspected rheumatoid meningitis.