Epstein‐<scp>B</scp>arr virus‐associated primary central nervous system cytotoxic <scp>T</scp>‐cell lymphoma

Primary central nervous system lymphoma (PCNSL) expressing T-cell markers is rare, among which nasal-type extranodal NK/T-cell lymphoma is an extremely rare subtype associated with Epstein-Barr virus (EBV) infection. Here we report the clinicopathologic features of a case of EBV-associated PCNSL showing a cytotoxic T-cell phenotype. The patient, a 73-year-old woman, presented with rapidly progressive mental deterioration. Brain MRI revealed multiple lesions with swelling in the bilateral cerebral hemispheres, which were hypointense on T1-weighted images, hyperintense on T2-weighted and fluid-attenuated inversion recovery images, and slightly hyperintense on diffusion-weighted images. Biopsy specimens from the temporal region showed many medium-sized anaplastic lymphocytic cells with perivascular and angio-invasive patterns in the cortex. Immunohistochemically, the cells were positive for CD3, CD8, T-cell-restricted intracellular antigen-1 (TIA-1), granzyme B and perforin, but negative for CD56 and CD20. In situ hybridization revealed EBV-encoded RNAs in the tumor cell nuclei. A rearrangement study showed T-cell receptor γ-chain gene rearrangement with a clonal appearance. The patient died 6 months after surgery, and a general autopsy revealed no lymphoma cells outside the brain. These cellular profiles are inconsistent with those of extranodal NK/T-cell lymphoma, and have not been previously described. This case appears to represent an unusual CNS manifestation of EBV-associated T-cell lymphoma.