Lentiform fork sign mimicking uremic encephalopathy in an atypical case of autoimmune limbic encephalitis

The lentiform fork sign (LFS) on MRI is often associated with uremic encephalopathy but is not pathognomonic. We present a case of autoimmune limbic encephalitis initially suspected as uremic encephalopathy despite normal renal function. A 58-year-old woman presented with seizures and altered mental status. MRI showed bilateral basal ganglia hyperintensities with the classic LFS. Normal renal parameters prompted cerebrospinal fluid analysis, which revealed anti-NMDA receptor antibodies, confirming autoimmune encephalitis. The patient improved markedly after immunotherapy. This case emphasizes the need to consider autoimmune causes of LFS and the importance of early diagnosis and treatment in preventing adverse outcomes.