Pearls & Oy-sters: Asymmetric meningeal involvement is a common feature of rheumatoid meningitis
PEARLS• Rheumatoid meningitis is a rare complication of rheumatoid arthritis that requires a meningeal biopsy for diagnosis.• Asymmetric meningeal involvement is a common, although not pathognomonic, brain MRI finding in rheumatoid meningitis.
OY-STERS• Because various immunosuppressants are used for the treatment of rheumatoid arthritis, a thorough investigation to exclude opportunistic infections should be conducted before the diagnosis of rheumatoid meningitis.• Immunoglobulin G4-related disease, granulomatous diseases such as granulomatosis with polyangiitis, neurosarcoidosis, neurosyphilis, and meningeal metastasis are possible considerations in the differential diagnosis of rheumatoid meningitis.CASE REPORT A 65-year-old woman with a 3-year history of rheumatoid arthritis presented with headache, confusion, a decreased level of consciousness, and recurrent left hemiparesis. Her rheumatoid arthritis was well-controlled with oral prednisolone, methotrexate, and leflunomide. Serum levels of rheumatoid factor and anticyclic citrullinated peptide antibody were 69.3 and 48.8 U/mL, respectively. Brain MRI revealed mild hydrocephalus and diffuse asymmetric high signal intensities with patchy nodules, which were prominent along the leptomeninges and subarachnoid space of the right frontoparietal lobe on fluid-attenuated inversion recovery (FLAIR) images and diffusionweighted imaging (DWI). Gadolinium uptake was observed in the leptomeninges over the right hemisphere on postcontrast T1-weighted images (figure 1, A-C). The results of CSF analysis showed an opening pressure of 15 cm H 2 O, leukocyte count of 20/mL (54% neutrophils, 31% lymphocytes, 15% other cells), protein level of 113.4 mg/dL, and glucose level of 43 mg/dL; however, within 2 weeks, the CSF opening pressure became elevated, reaching 27 cm H 2 O. In addition, CSF rheumatoid factor was detected at a level of 17.6 IU/mL. An extensive workup for infectious diseases, autoimmune diseases including vasculitis, and leptomeningeal metastasis was performed. CSF cytology for malignant cells as well as Gram stain and culture were negative. Tests for Mycobacterium tuberculosis and fungus in the CSF were negative. CSF PCR results for Hemophilus influenzae, Streptococcus agalactiae, Neisseria meningitidis, Streptococcus pneumoniae, Listeria monocytogenes, herpes simplex virus, varicella-zoster virus, EpsteinBarr virus, cytomegalovirus, and enterovirus were negative. Serum levels of immunoglobulin G subclass IV (IgG4), antinuclear antibody, anti-neutrophil cytoplasmic antibodies, anti-dsDNA antibody, antiRo/La antibodies, and angiotensin converting enzyme were normal. The EEG results showed regional slowing in the right frontocentral region. A biopsy from the right frontal meninges revealed necrotic granulomatous inflammation with dense infiltration of CD68-positive histiocytes as well as focal vasculitis in the leptomeninges ( figure 1, D-F). Rheumatoid nodules were not...