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Glioblastoma Mimicking Autoimmune Encephalitis
Connor M Tierney1, Marinos Kontzialis2
1Department of Radiology, Northwestern Medicine, Chicago, IL, USA.
Abstract:
A 66-year-old female patient presented with progressive short-term memory loss over a period of three months and mild gait imbalance. MRI of the brain demonstrated symmetric expansile T2 FLAIR hyperintensities within the bilateral mesial temporal lobes, thalami, and cingulate gyri (Figure 1). Due to the symmetry of the signal changes in the bilateral cerebral hemispheres and especially the mesial temporal lobes, an autoimmune encephalitis was strongly favored on imaging. Glioblastoma was a consideration on the initial scan; however, it was thought to be much less likely, and the patient received immunosuppression with plasmapheresis and IV steroids. At that time, it was even presumed that the patient improved mildly with plasmapheresis. The patient was discharged on PO steroids; however, a few weeks later the patient presented in status epilepticus. On repeat MRI brain, findings were not significantly changed, and the diagnosis of an autoimmune process was again favored on imaging. The patient received plasmapheresis and IV steroids. However, on the second admission the patient's neurologic function was markedly below baseline per the family's report. The patient had received an extensive autoimmune, infectious and metabolic work up, including testing for Creutzfeldt-Jacob disease, with all the tests coming back negative. Therefore, a brain biopsy was performed to understand the underlying pathology, IDH wild-type glioblastoma. On MRI, the expansile signal changes were bilateral and multifocal, affecting more than three cerebral lobes. This is a case of gliomatosis cerebri, which was misdiagnosed as autoimmune encephalitis due to the symmetry of cerebral involvement.
Insights
Gliomatosis cerebri, a rare brain tumor, can mimic autoimmune encephalitis due to symmetric MRI findings. This case highlights the importance of considering glioblastoma, even with atypical presentations, to ensure accurate diagnosis and treatment.
Area of Science:
- Neuro-oncology
- Neuroradiology
- Neuropathology
Background:
- Autoimmune encephalitis and glioblastoma can present with overlapping symptoms and imaging findings.
- Symmetric brain lesions on MRI can lead to misdiagnosis, particularly in differentiating inflammatory from neoplastic processes.
- Gliomatosis cerebri is a rare form of diffuse glioma that presents challenges in early diagnosis.
Purpose of the Study:
- To report a case of gliomatosis cerebri initially misdiagnosed as autoimmune encephalitis.
- To emphasize the importance of considering neoplastic processes in cases with symmetric brain lesions on MRI.
- To highlight the diagnostic challenges and the role of brain biopsy in confirming the diagnosis.
Main Methods:
- A 66-year-old female patient with progressive memory loss and gait imbalance.
- Initial MRI showing symmetric T2 FLAIR hyperintensities in mesial temporal lobes, thalami, and cingulate gyri, favoring autoimmune encephalitis.
- Treatment with immunosuppression (plasmapheresis, steroids) followed by repeat MRI and eventual brain biopsy confirming IDH wild-type glioblastoma (gliomatosis cerebri).
Main Results:
- The patient's initial presentation and MRI findings were suggestive of autoimmune encephalitis, leading to immunosuppressive therapy.
- Despite treatment, neurological function declined, prompting further investigation.
- Brain biopsy revealed IDH wild-type glioblastoma, specifically gliomatosis cerebri, with diffuse and multifocal involvement across cerebral lobes.
Conclusions:
- Symmetric and multifocal brain lesions on MRI can be a challenging diagnostic feature, potentially mimicking inflammatory conditions like autoimmune encephalitis.
- Gliomatosis cerebri should be considered in the differential diagnosis of such presentations, even when autoimmune etiologies are strongly suspected.
- Brain biopsy remains a critical tool for definitive diagnosis in ambiguous cases, guiding appropriate oncological management.
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