Status Epilepticus as the Initial Manifestation of Follicular Lymphoma with Leptomeningeal Dissemination

Follicular lymphoma (FL) rarely presents with central nervous system involvement at the time of the diagnosis. We describe the case of a 44-year-old man who presented with meningoencephalitis and subsequently developed status epilepticus due to diffuse leptomeningeal dissemination of grade 1 FL. Cerebrospinal fluid (CSF) cytology yielded negative results, but flow cytometry detected monoclonal B-cell proliferation, leading to a diagnosis. Rapid neurological recovery was achieved after immunochemotherapy. This case underscores the importance of CSF flow cytometry in mononuclear cell-predominant meningoencephalitis that is unresponsive to empirical therapy.