BACKGROUND
Cryptococcal meningitis usually occurs in people with impaired cellular immunity, but it can also affect patients without a recognized immunodeficiency. Cerebrospinal fluid (CSF) shunts complicate recognition because symptoms may be subtle and serum studies may be unrevealing. We describe a case of a patient with a longstanding ventriculoatrial (VA) shunt whose CSF findings established the diagnosis despite a negative serum cryptococcal antigen result.
CASE REPORT
A 60-year-old man with a remote ventriculoperitoneal shunt subsequently converted to a VA shunt developed persistent headache and an episode of seizure-like activity 3 days after robotic cholecystectomy. He had no focal neurological deficit, and electroencephalography showed no epileptiform activity. Brain magnetic resonance imaging showed no mass lesion or hydrocephalus. Lumbar puncture revealed lymphocytic pleocytosis (101 cells/μL), CSF protein of 61 mg/dL, and glucose of 44 mg/dL. Serum cryptococcal antigen was negative, whereas CSF cryptococcal antigen was positive at a titer of 1: 40 and CSF culture grew Cryptococcus neoformans. The discordant serum result has an uncertain mechanism because assay-platform details and repeat or dilution testing were unavailable. He received liposomal amphotericin B and flucytosine, underwent VA shunt removal and external ventricular drainage, and later had shunt revision. Following clinical and microbiologic improvement, he received fluconazole consolidation and maintenance therapy and remained clinically well at 4-week follow-up.
CONCLUSIONS
A negative serum cryptococcal antigen result did not exclude meningitis in this patient with a CSF shunt. Persistent unexplained neurological symptoms warrant CSF evaluation when cryptococcosis remains clinically plausible. This case also illustrates the importance of antifungal therapy and coordinated neurosurgical management for suspected shunt-associated infection.

Keywords: Cerebral Cortex; Cryptococcus; Meningitis