We aimed to determine relative incidence, survival, and predictors of outcome in primary dural lymphomas.

Primary dural lymphoma (PDL) is a rare subtype of primary CNS lymphomas that arises from the dura mater. Population-based incidence data and clinical experience are scarce.

We retrospectively searched the institutional databases of the Divisions of Neuro-Oncology at the Massachusetts General Hospital and the Yale School of Medicine for patients with primary CNS lymphoma (n=316). In cases with pathologically confirmed dural lymphoma and no evidence of primary parenchymal cerebral or systemic involvement, we recorded demographic and histological data; diagnostic findings; treatment; and outcome.

Twenty patients with PDL were identified between 2001-2018, representing 6.3% of individuals with primary CNS lymphomas. PDL mostly arose from the intracranial dura (17/20 patients). We encountered diffuse large B-cell lymphomas (10/20 patients); marginal zone lymphomas (6/20); follicular lymphomas (2/20); undefined B-cell non-Hodgkin lymphoma (1/20); and T-cell non-Hodgkin lymphoma (1/20). Symptoms were attributed to tumor mass effect. On imaging studies, all patients had dural-based tumors with diffuse contrast enhancement. Lesions showed predominatly high signal on diffusion-weighted imaging (DWI)-MRI and apparent diffusion coefficient (ADC)-ratio from tumor to white matter was 0.83±0.03. CSF analysis was mostly unrevealing, and diagnosis rested upon tissue analysis. Localized (surgery; stereotactic or involved-field radiation therapy) or systemic treatments (steroids; chemotherapy) were provided. Median overall survival (OS) was not reached after five years. Five patients progressed and three patients are deceased. Localized and systemic treatment were equivalent in terms of OS. Ten patients had surgical resection other than biopsy, and extent of resection positively correlated with improved OS (p=0.042).

PDL is a rare variant of primary CNS lymphomas. A high level of suspicion is required for diagnosis as imaging and CSF analysis are non-specific. Outcome is excellent with multimodality therapy. Aggressive surgery may convey a survival advantage in selected cases.