Incidence and pathology of primary brain lymphoma in Hong Kong Chinese patients

Primary brain lymphoma (PBL) is an uncommon extranodal lymphoma. Its incide nce is rapidly increasing in both immunocompromised and immunocompetent pat ients in Western countries. Eighteen cases of PBL were identified during a 16-year period among HIV negative patients in Queen Mary Hospital, Hong Kon g. One case of post-transplantation lymphoproliferative disease (PTLD) was positive for Epstein Parr virus (EBV) encoded RNA (EBER) by in situ hybridi zation. All the remaining 17 immunocompetent cases were classified as diffu se large B-cell lymphoma, except for one case of Burkitt's lymphoma. EBER e xpression was negative in all 13 cases tested. Immunostaining for bcl-2 and bcl-6 was positive in 8/11 and 6/11 cases tested, with heterogeneous combi nation of expression and intensity. The incidence rate of PBL in immunocomp etent patients was stable at 1.03 per million per year. The incidence of PB L in post transplantation (0.16%) and HIV related setting (0.29%) is also l ow in Chinese. PBL in Chinese patients is almost uniformly represented by E BV negative, diffuse large B-cell lymphoma, confined to the brain. However, the molecular pathogenesis may be heterogeneous.