Mantle cell lymphoma with aseptic meningitis mimicking hydrocephalus on brain imaging.

An 83-year-old man underwent head computed tomography (CT) to investigate cognitive decline and gait disturbance and was admitted to undergo a cerebrospinal fluid (CSF) tap test for suspected idiopathic normal-pressure hydrocephalus. He had a history of chemotherapy for mantle cell lymphoma (MCL), but CT on admission showed no evidence of recurrence. After admission, his level of consciousness rapidly deteriorated and CSF examination suggested infiltration of MCL into the central nervous system (CNS). Although CNS involvement in MCL is rare, this case demonstrates that even if recurrence of MCL is not suspected based on CT findings.