Anti-N-methyl-d-aspartate receptor encephalitis: mimicker of lupus and multiple sclerosis.

Anti-N-methyl-d-aspartate receptor encephalitis (NMDARE) is a B-cell-mediated autoimmune encephalitis with wide non-specific symptoms like acute-onset psychiatric or neurological ones mimicking various other conditions. A careful history and appropriate workup, including cerebrospinal fluid analysis for anti-NMDAR antibodies, imaging, and electroencephalogram, should be conducted, considering all differential diagnoses that can mimic its presentation. Combination therapy with high-dose steroids, plasma exchange, or immunoglobulin therapy has been shown to be more efficacious. In patients who fail first-line therapy, rituximab or cyclophosphamide should be considered. It is essential to rule out ovarian teratoma or other occult malignancies that can cause NMDARE, as removal of the tumor itself resolves this condition. Timely diagnosis and early intervention are necessary to avoid an untoward outcome.