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Epstein‐Barr virus‐positive lymphoproliferative disorder associated with old organized chronic subdural hematoma

This report describes a case of an immunocompetent 77‐year‐old male with Epstein‐Barr virus (EBV)‐positive lymphoproliferative disorder associated with calcified chronic subdural hematoma (CSH). On the day prior to consultation in our outpatient clinic, the patient fell from his bed, striking his frontal head on the floor. Magnetic resonance imaging showed ill‐defined lesions in the right frontal‐temporal subdural regions. At surgery, a hard and thickened outer membrane of a CSH and muddy organized subdural hematoma were observed. However, macroscopic neoplastic lesions were not apparent. Histologically, there were atypical lymphoid cells scattered or conglomerated in some areas of the thick outer membrane of the CSH. They were composed of occasional large atypical lymphoid cells. The lesions were accompanied by necrosis. Atypical lymphoid cells were immunopositive for B‐cell markers but not for T‐cell markers. EBNA2 was seen in the nuclei of tumor cells. Atypical lymphoid cells showed positive signals for EBV‐encoded small RNAs (EBERs) on in situ hybridization. These findings were consistent with EBV‐positive lymphoproliferative disorder associated with CSH. These results also suggested that EBV and the inflammatory reaction found in the CSH could be the etiological factors in the pathogenesis of lymphoproliferative disorder.