Additionally, chest and abdominopelvic CT scans were performed to assess for occult neoplasia, along with measurement of adenosine deaminase (ADA) levels in the CSF and testing for neurotropic viruses, including tick-borne encephalitis (TBE), Toscana, West Nile, and lymphocytic choriomeningitis (LCM). Here, ADA is linked to neoplasm.