Glioblastoma Masquerading as a Presumed Ischemic Stroke: A Case of Delusional Jealousy and Fluctuating Psychosis.

Psychiatric symptoms can be the presenting or dominant manifestation of an underlying brain tumor, and this phenomenon is frequently misattributed to a primary psychiatric disorder, particularly when a plausible alternative explanation, such as a recent stroke or a known alcohol use disorder, is already present. We report a case in which glioblastoma was ultimately identified as the cause of a subacute psychotic syndrome that had initially been attributed to a preceding cerebrovascular diagnosis. A 64-year-old man with a history of alcohol use disorder was admitted to Internal Medicine with a diagnosis of ischemic stroke in the left middle cerebral artery territory, with new-onset seizures at admission and a self-limited episode of hyperactive delirium. Four days after discharge, he was brought to a psychiatric emergency service with heteroaggression toward his wife, near-total insomnia, pressured speech, and delusions of infidelity and persecution. A head computed tomography scan and initial laboratory workup, including toxicology, were unremarkable, and he was admitted to Psychiatry with a presumptive diagnosis of new-onset psychotic disorder. Over 14 days, despite escalating antipsychotic therapy, he developed progressively incoherent speech, disorientation, and a fluctuating level of consciousness alternating between agitation and obnubilation. Family interviews clarified that his premorbid jealousy had been alcohol-related and transient, unlike the fixed, treatment-refractory delusion now present, and that confusion and fluctuating consciousness were new since the stroke admission. Magnetic resonance imaging revealed an infiltrative left temporo-insular and basal ganglia lesion radiologically consistent with glioblastoma, later confirmed histologically as an isocitrate dehydrogenase-wildtype, grade 4 tumor. The patient underwent subtotal resection; treatment was later limited to palliative care because of tumor progression, and he died five months afterward. This case illustrates that fluctuating consciousness, disorientation, and treatment-refractory psychosis in a patient with a recent stroke or seizure disorder should prompt reconsideration of the working diagnosis and contrast-enhanced magnetic resonance imaging, since a normal computed tomography scan does not exclude an infiltrating glioma, and neighboring organic syndromes can mimic one another both clinically and radiologically.