Cognitive decline in elderly patients is frequently attributed to neurodegenerative conditions such as dementia. However structural brain lesions including glioblastoma and primary central nervous system lymphoma (PCNSL), can present with similar symptoms, leading to potential misdiagnosis and delayed treatment. This presentation describes the case of a 79-year-old male initially referred for memory assessment following progressive cognitive decline and behavioral changes, including confusion and wandering. Initially referred for dementia assessment, he had no focal neurological deficits, and an initial CT head scan was unremarkable. Despite conservative management, his condition deteriorated. A detailed collateral history revealed visual disturbances, bradycardia and more rapid cognitive decline than typical of primary dementia syndromes. MRI of the brain revealed a large, irregular lesion involving the right basal ganglia, thalamus, and corpus callosum, raising suspicion for glioblastoma or PCNSL. Due to the patient’s frailty and poor functional reserve, a neuro-oncology multidisciplinary team recommended best supportive care without biopsy. This case illustrates the importance of considering structural pathology in elderly patients presenting with atypical or rapidly progressive cognitive symptoms, even in the absence of focal neurology or abnormal CT findings. It highlights the limitations of CT imaging, the diagnostic value of MRI, and the need for a high index of suspicion when presentations deviate from typical dementia trajectories. The case also reflects on ethical decision-making and the role of multidisciplinary discussions in managing frail patients.

Dr George Okwuasaba is a physician in the Geriatrics Department at Scarborough General Hospital, United Kingdom. He has a strong interest in diagnostic medicine and geriatric cognitive health, particularly in the intersection of neurology and aging. With experience managing complex elderly patients in both acute and community settings, Dr Okwuasaba focuses on holistic, multidisciplinary care and advocates for timely and appropriate investigation of cognitive symptoms in older adults.