Clinicopathological features of primary epidural B-cell lymphoma: a study of 14 cases.

Primary epidural B-cell lymphoma (PEBL) is a rare neoplasm that presents initially with involvement of the epidural space. This study aimed to characterise the clinicopathological features of PEBL through a retrospective analysis of cases diagnosed at two institutions over a 15-year period. A total of 14 patients were identified, including seven women and seven men, with a median age of 63.5 years (range 21-76 years). These patients most often presented with symptoms of spinal cord compression, such as extremity paraesthesias, pain, and weakness. The thoracic region or thoracolumbar region was commonly involved in 10 (71%) patients. Eight (57%) patients had Lugano stage I disease, and 6six (43%) had stage II disease. Nine (64%) patients had a low or low-intermediate International Prognostic Index (IPI) score, and four (29%) patients had a high-intermediate or high score. All patients underwent surgical excision of the epidural mass, and histological analysis showed diffuse large B-cell lymphoma (DLBCL) in eight patients, follicular lymphoma in five patients, and high-grade B-cell lymphoma (HGBL) in one patient. Immunohistochemical analysis showed that all 14 cases were positive for pan B-cell markers and negative for CD3. Using the Hans algorithm, seven DLBCL cases had a germinal centre B-cell (GCB) immunophenotype and one case had a non-GCB immunophenotype. Fluorescence in situ hybridisation (FISH) analysis performed on eight cases showed one case of HGBL with MYC and BCL6 rearrangements, four cases of DLBCL with isolated BCL2 (n=2) or BCL6 (n=2) rearrangements, and one case of DLBCL with BCL2 and BCL6 rearrangements. All 14 patients were treated with excision, 12 of whom were also treated with chemotherapy; three of these patients also received radiation therapy. One patient was treated with an autologous stem cell transplant and subsequently CAR-T therapy. Clinical follow-up was available for all patients with a median of 39.5 months (range 1-123 months). At the last follow-up, 13 patients were alive and in complete remission and one patient with HGBL died 9 months after diagnosis. We conclude that PEBL predominantly arises in older adults and most often affects the thoracolumbar region. Patients usually have a low or low-intermediate IPI score. The most frequent type of lymphoma is DLBCL with a GCB immunophenotype. In this cohort, most patients received chemotherapy and had a favourable prognosis.