Recovery from coma caused by primary CNS mantle cell lymphoma presenting as encephalitis

We report a 74-year-old woman with progressive cognitial deterioration and changes in personality. She had no clinical signs of an inflammatory CNS process, but brain CT and MRI scans and cytologic examination of the CSF were initially indicative of encephalitis and ventriculitis. Antiviral and antibacterial therapy had no effect on the course of symptoms, and the patient became comatose. We established the diagnosis of a primary CNS mantle cell lymphoma (PCNSL) and began corticosteroids. Within a few days the patient became alert and was able to walk again. Nonenhancing and non-space-occupying PCNSLs are rare but must be considered in the differential diagnosis of coma and encephalitis. Comatose PCNSL patients without radiographic evidence for herniation can be successfully treated with corticosteroids even if the EEG has a burst suppression pattern.