Clinical and molecular features of primary spinal epidural lymphomas.

Lymphomas confined to the spinal epidural space at initial diagnosis are rare and referred to as primary spinal epidural lymphoma (PSEL). This study presents clinical, histopathological, and molecular insights from 13 PSEL cases, including follicular lymphoma (PSEL-FL, N = 4), extranodal marginal zone lymphoma (PSEL-MZL, N = 3), diffuse large B-cell lymphoma (PSEL-DLBCL, N = 5), and Burkitt lymphoma (PSEL-BL, N = 1). Despite localized presentation at initial diagnosis, PSEL with aggressive histologies demonstrated remarkably unfavorable outcomes, contrasting the highly indolent clinical course observed in indolent PSEL, particularly PSEL-FL. Molecular analysis showed similarities to nodal counterparts and separation by entity. Comparison of PSEL-FL and classic FL revealed activated tumor microenvironment-associated pathways, potentially supporting extranodal lymphoma growth in this rarely affected spinal epidural site.