Primary brain T-cell lymphoma in an HTLV-1 serologically positive male.

Primary central nervous system lymphoma (PCNSL) is a subgroup of extranodal non-Hodgkin lymphoma usually due to B-cells. The incidence of T-cell PCNSL is 1-4% in Western countries. Human T-lymphotropic virus (HTLV-1) causes tropical spastic paraparesis/myelopathy and adult T-cell leukemia/lymphoma. We describe the extremely rare occurrence of T-cell PCNSL in a 29 year old HTLV-1 carrier. Additional unusual features of the case included the patient's young age and normal cerebrospinal fluid cytological findings, without leptomeningeal spread. Given the long latency between HTLV-1 infection and disease manifestation, more such cases may be diagnosed in the future. We recommend that every patient with T-cell PCNSL be screened for HTLV-1.