Whole brain radiation therapy for primary central nervous system marginal zone lymphoma: a case report.

A standard radiation therapy protocol for primary central nervous system marginal zone lymphoma (CNS-MZL) has not been established. The International Lymphoma Radiation Oncology Group suggested a radiation therapy dose of 30-36 Gy for lesions of well-defined CNS-MZL. We report a case of relatively low-dose whole brain radiation therapy (WBRT) for ill-defined CNS-MZL. A 56-year-old man who presented with sudden left-sided convulsions and impaired consciousness was diagnosed with CNS-MZL. The tumor had an ill-defined lesion, without cerebrospinal fluid involvement. WBRT, consisting of 25.2 Gy in 14 fractions, was administered owing to the difficulty in target delineation for focal radiation therapy. No chemotherapy was administered during the treatment course. After the 36-month follow-up period, the patient maintained complete remission without neurological disorders. This report describes the usefulness of relatively low-dose WBRT for ill-defined CNS-MZL. © The Japan Society of Clinical Oncology 2020.