West Nile Virus Encephalitis in a Patient with Neuroendocrine Carcinoma

Oftentimes, when patients with metastatic cancer present with acute encephalopathy, it is suspected to be secondaryto their underlying malignancy. However, there are multiple causes of delirium such as central nervous system (CNS) infections,electrolyte abnormalities, and drug adverse reactions. Because West Nile Virus (WNV) neuroinvasive disease has a high mortalityrate in immunosuppressed patients, a high index of suspicion is required in patients who present with fever, altered mental status,and other neurological symptoms.Observations. Our case report details a single patient with brain metastases who presented withunexplained fever, encephalopathy, and new-onset tremors. Initially, it was assumed that his symptoms were due to his underlyingmalignancy or seizures. However, because his unexplained fevers persisted, lumbar puncture was pursued. Cerebrospinal fluidanalysis included WNV polymerase chain reaction and serologies were ordered which eventually led to diagnosis of WNVencephalitis.Conclusions and Relevance. Patients with metastatic cancer who present with encephalopathy are often evaluatedwith assumption that malignancy is the underlying etiology. This can lead to delays in diagnosis and possible mistreatment. Ourcase highlights the importance of maintaining a broad differential diagnosis and an important diagnostic consideration of WNVencephalitis in patients with cancer