PRIMARY T-CELL CNS LYMPHOMA MIMICKING VASCULITIS

A 29 year old male presented with headache and no neurological signs. MRI brain strongly suggested an aggressive primary brain tumour in the right frontal lobe but histopathology revealed a pleomorphic lymphoid infiltrate, necrosis and vague granulomata and vasculitis was diagnosed. There was aggressive clinico-radiological progression despite two debunking surgeries, corticosteroids and cyclophosphamide. On review the following were noted: areas of necrosis and focal diffuse lymphoid infiltrate showing perivascular cuffing; the presence of granuloma formation and vascular necrosis was less certain; overwhelming predominance of T-cells within the parenchyma; high T-cell mitotic activity and the mild nuclear atypia of the T-cells. PCR demonstrated no clonal immunoglobulin gene but showed a T-cell receptor gene rearrangements. The diagnosis was revised to primary T-cell CNS Lymphoma. Arabinoside & methotrexate were administered. Cerebral vasculitis may present with the imaging appearances of a malignancy. In the current case, a mass lesion was misdiagnosed as vasculitis due to atypical histopathology.