Acute Seizures and Aphasia in a Patient With Suspected Systemic Lupus Erythematosus: A Diagnostic Puzzle Unveiling Diffuse Hemispheric Glioma, H3 G34-Mutant

Diffuse hemispheric glioma, H3 G34-mutant (DHG-H3-G34), is a rare, newly defined WHO grade 4 glioma. Its nonspecific symptoms and radiologic heterogeneity can mimic infectious, autoimmune, and paraneoplastic neurologic disorders, complicating timely diagnosis. We present a case of a 20-year-old man with a history of suspected systemic lupus erythematosus who presented with acute encephalopathy, seizures, and aphasia. He underwent an extensive workup to evaluate for possible encephalitis. Biopsy ultimately revealed the diagnosis of DHG-H3-G34. This case highlights the importance of maintaining a broad differential in young patients with acute neurologic decline. Early consideration of neoplasms is crucial to avoid diagnostic delays in high-grade gliomas.