A Case of Primary Central Nervous System B-cell Lymphoma Resembling Autoimmune Encephalitis
Joyce Jimenez Zambrano1, Jakob Plagenz1, Cody Boyle2, Scott Belliston1
1Department of Neurology, University of North Dakota School of Medicine and Health Sciences & Sanford Health, 2University of North Dakota School of Medicine and Health Sciences
Objective:
To describe a unique case of primary central nervous system B-cell lymphoma associated with false-positive Glial Fibrillary Acidic Protein (GFAP) and N-Methyl-D-Aspartate Receptor (NMDAR) antibodies.
Background:
Primary central nervous system lymphoma (PCNSL) is a rare, but highly aggressive form of extranodal non-Hodgkin lymphoma. The clinical manifestations of PCNSL are often nonspecific, complicating the differential diagnosis with conditions such as autoimmune encephalitis (AE). The presence of positive antibodies further complicates the diagnosis and management of PCNSL.
Results:
A 67-year-old woman presented with a 6-week history of confusion, word-finding difficulties, and behavioral changes. On examination, she exhibited disorientation to time and place, flat affect, dysnomia, and impaired delayed recall. Magnetic resonance imaging of the brain revealed enhancement involving the left hippocampus, left basal ganglia, and the left frontal corona radiata, associated with T2 hyperintense signal in these regions. Cerebrospinal fluid (CSF) analysis showed a white blood cell count of 111 with 98% lymphocytic predominance, glucose levels of 106 mg/dL, and protein levels of 61 mg/dL. Cytology results were negative and oligoclonal bands were positive. GFAP and NMDAR antibodies were detected in the CSF. Following these findings, the patient was treated with high-dose methylprednisolone and underwent plasma exchange with initial symptom improvement. However, after three weeks, her condition declined. She became lethargic, aphasic, and developed right-sided weakness. A left frontal stereotactic biopsy was performed, and pathology showed diffuse large B-cell lymphoma. Unfortunately, the patient transitioned to comfort measures and died prior to obtaining the biopsy results.
Conclusions:
PCNSL can present clinical and laboratory features similar to those of autoimmune encephalitis, including the presence of neural and glial antibodies. PCNSL should be suspected in cases where there is clinical decline despite immunotherapy, as a misdiagnosis of autoimmune encephalitis can contribute to significant morbidity and mortality.
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