Abstracts

Rationale: The most common etiology of discrete parenchymal lesions in patients presenting with new onset seizures includes neoplastic and cerebrovascular disease, although discrete inflammatory lesions, including demyelinating diseases, vasculopathies or infections, have also been reported.Methods: We report three patients presenting with acute uncontrolled seizures with discrete brain lesions on magnetic resonance imaging (MRI) presumed to be neoplastic that were subsequently found to be related to an underlying immune-mediated inflammatory process.Results: All three patients presented with focal seizures with secondary generalization that did not respond adequately to AES treatment. Brain MRI showed T2 hyperintense lesions in the left parietal lesion with rapidly evolving edema in Patient 1, discrete left temporal lesion in Patient 2 and a discrete, cystic mass in the left parietal lobe in Patient 3. In addition, Patient 3 had abnormal signal changes in the left temporal lobe and hypothalamus. All 3 patients underwent stereotactic brain biopsy and subsequent resection of the lesion (Patients 1 and 2) or autopsy (Patient 3). Patient 1 had a confirmed plasma cell granuloma. Patient 2 had neuronal necrosis, prominent reactive astrocytosis, microglial activation, with sparse mononuclear inflammation. Patient 3 had a non-necrotizing lymphocytic encephalitis of the gray matter and was subsequently diagnosed with anti-voltage gated potassium channel and anti-glutamic acid decarboxylase autoimmune encephalitis. Patients 1 and 2 did well after microsurgical resection of the lesion and remain seizure free to date (> 3 years). Patient 3 had subsequent complications including hypothalamic dysfunction and status epilepticus and expired after withdrawal of care.Conclusions: We present three cases of patients with acute uncontrolled seizures who had prominent discrete lesions on MRI suggesting a focal pathology consistent with a neoplastic process. Histopathological findings deviated from the presumed diagnosis of neoplasm and included autoimmune encephalitis and plasma cell granuloma. These findings indicate that patients presenting with acute uncontrolled seizures with discrete lesions on MRI may have underlying immune mediated inflammatory process and that stereotactic biopsy may be warranted earlier to direct treatment.