Central nervous system lymphoma: Patterns of incidence in Indian population and effect of steroids on stereotactic biopsy yield

Background: Epidemiology of primary central nervous system lymphoma (PCNSL) world-wide shows an increase in incidence linked to human immunodeficiency virus (HIV) pandemic. Materials and Methods: This retrospective review of case records analyzed the trends of hospital-based incidence of PCNSL over two decades (1991-2010), relation to immune status and effect of steroids on yield of stereotactic biopsy (STB). Results: A total of 76 cases of PCNSL were diagnosed over a period of two decades. Incidence of lymphomas amongst all biopsied lesions showed a gradual increase from 0.18% at the beginning of study period to 0.41% at the end of study period. Only 8.6% (3 of 35 tested) of the PCNSL patients were positive for HIV. The mean age of patients with HIV infection (31.3 +/- 3.5 years) was significantly lower compared with those without HIV infection (44.7 +/- 10.9 years) (P = 0.033). Diagnosis was obtained by open biopsy in 32 patients (42.1%) and STB in 44 patients (57.9%). Open biopsy yielded a histological confirmation of PCNSL in all cases. Among those who underwent STB, the incidence of negative biopsy with short duration of steroids (<= 1 week) was 33.3% and increased to 57.1% with increasing duration of steroid treatment (> 1 week). Conclusions: This study documented an increase in hospital based incidence of PCNSL in our institute, independent of HIV association. Steroid intake administration for more than a week prior to biopsy adversely affected the yield of STB in PCNSL.