Herpes simplex encephalitis in patients with cancer

Area of Science:

• Neuroscience
• Oncology
• Infectious Diseases

Background:

• Chemotherapy, corticosteroids, and radiotherapy (RT) are suspected risk factors for herpes simplex encephalitis (HSE).
• Previous studies include case reports and animal models, lacking large-scale human data.

Purpose of the Study:

• To investigate the incidence and characteristics of HSE in cancer patients.
• To assess the potential increased risk associated with cancer treatments like cranial RT.

Main Methods:

• Retrospective analysis of HSE cases at a cancer care hospital over 12 years.
• Patient identification via positive herpes simplex virus (HSV) PCR in CSF or brain pathology.
• Review of patient history, including treatments (chemotherapy, dexamethasone, RT) and MRI findings.

Main Results:

• Seven HSE cases identified, with four having received cranial RT.
• Incidence in RT patients higher than general population estimates.
• Five patients received recent chemotherapy; three were on dexamethasone.
• Typical MRI findings observed; however, normal CSF white blood cell count occurred in four patients, three with prior RT and dexamethasone.
• One patient had negative CSF PCR but confirmed HSE at autopsy.

Conclusions:

• The risk of HSE may be elevated in cancer patients, especially those undergoing cranial RT.
• Cerebrospinal fluid (CSF) analysis may be misleading in this population, necessitating consideration of clinical and imaging data.
• Early recognition and diagnosis are crucial, despite potential challenges in CSF testing.