Miliary brain metastases presenting as rapidly progressive dementia

Area of Science:

• Neurology
• Oncology
• Pathology

Background:

• Rapidly progressive dementia (RPD) presents a diagnostic challenge, often mimicking neurodegenerative conditions like dementia with Lewy bodies or Creutzfeldt-Jakob disease (CJD).
• The sudden onset of neurological symptoms post-surgery necessitates a broad differential diagnosis, including rare causes.
• Metastatic cancer can present with diverse neurological symptoms, including cognitive decline.

Observation:

• A 79-year-old woman developed RPD with severe memory loss, visual hallucinations, and extrapyramidal signs after hip surgery.
• Neurological deterioration progressed to akinetic mutism over five months, with seizures appearing terminally.
• Initial investigations, including MRI and CSF analysis, were inconclusive for common causes of RPD.

Findings:

• Neuropathological examination revealed extensive miliary metastatic adenocarcinoma, likely of pulmonary origin, despite no known primary tumor.
• Alzheimer's disease histopathological changes were noted, but Lewy bodies and PrP deposits were absent.
• The clinical presentation suggested a possible link between a pathological fracture, microembolic dissemination, and the sudden onset of dementia.

Implications:

• Metastatic cancer, particularly from an unknown primary, should be considered in the differential diagnosis of RPD, especially with sudden onset post-trauma or surgery.
• This case underscores the critical role of post-mortem neuropathological examination in identifying rare causes of dementia.
• Understanding such rare presentations can improve diagnostic accuracy and potentially guide future therapeutic strategies for dementia.