Follicular lymphoma with secondary central nervous system relapse: a case report and literature review.

Secondary central nervous system (CNS) relapse by aggressive non-Hodgkin's lymphoma is a well-known complication portending a very poor prognosis. Conversely, patients with indolent lymphoma-like follicular lymphoma (FL) rarely present with CNS involvement and, thus, limited information is currently available. We herein describe a patient with FL who developed CNS involvement during chemotherapy. Treatment including high-dose methotrexate and radiation therapy was ineffective and the patient died 5 months after CNS relapse. In a literature review, there were 8 case reports of the secondary CNS relapse of FL. The findings obtained suggest that bone marrow infiltration is a risk factor for CNS relapse. Moreover, 5 out of 9 patients died within 2.5 years, indicating a poorer prognosis than that of FL. Therefore, it is important to promptly perform detailed examinations as soon as neurological findings appear.