Rising incidence of primary central nervous system lymphoma in Kumamoto, Japan

BackgroundPrimary central nervous system lymphoma is an extranodal form of non-Hodgkin lymphoma arising in the craniospinal axis. The incidence of PCNSL is reportedly on the increase in some parts of the world in the last 2 decades.MethodsWe surveyed 4007 patients diagnosed with PIT between 1989 and 2004, with histologic diagnosis being obtained in 70% of the patients. Of these, the PCNSL cases were reviewed.ResultsOf 4007, 136 (3.4%) carried a diagnosis of PCNSL. At 0.41 per 100,000 per year, the age-adjusted incidence rate for that period was higher than that for the period from 1989 to 1998 (0.29 per 100,000 per year). Moreover, the number of patients with PCNSL doubled from 45 (1989-1996) to 91 (1997-2004).ConclusionsOur findings point to an increase in the incidence of PCNSL among immunocompetent individuals in Kumamoto Prefecture.