Epstein-Barr virus-positive diffuse large B-cell primary central nervous system lymphoma associated with organized chronic subdural hematoma: a case report and review of the literature.

We here report on a rare case of Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) detected in both brain parenchyma and in an organized chronic subdural hematoma (OCSH). A 96-year-old man diagnosed with asymptomatic OCSH in the left frontal convexity was referred to our hospital because of a de novo mass lesion just beneath the OCSH on contrast-enhanced magnetic resonance imaging. The size of the OCSH remained stable. We diagnosed the lesion as a malignant tumor. At surgery, the organized hematoma and the soft fragile tumor were removed. Histological examinations revealed pleomorphic lymphoid cells not only in the brain tissue but also in the OCSH component with tumor necrosis, and these were immunopositive for B-cell markers. In situ hybridization revealed positive signals for EBV-encoded small RNAs, consistent with EBV-positive DLBCL. Since the membranes of the subdural hematoma were fibrous and the tumor progression resulted in necrosis of the tumor, the DLBCL may have originally developed in the OCSH and infiltrated into the brain parenchyma. We believe that this rare case provides crucial information for the understanding of DLBCLs associated with OCSH.