Significant increase in the relative frequency of follicular lymphoma in Taiwan in the early 21st century

Lymphoma subtype varies in different geographic areas. Follicular lymphoma (FL) is the most common lymphoma subtype in the USA, accounting for 35% of adult non-Hodgkin lymphoma (NHL).1 The worldwide incidence of FL is 22%, with lower incidence in Europe and Asia, and in underdeveloped countries.2 3 Hodgkin lymphoma (HL) accounted for 3.9% of 205 malignant lymphomas in the author’s institution, Chi-Mei Medical Centre in southern Taiwan, from January 1989 to December 1998.4 During that period, the most common B-cell lymphoma subtypes were diffuse large B-cell lymphoma (DLBCL, 47.2%) and marginal zone lymphoma (MZL, 20.8%), while FL ranked as the third at a low frequency of 6.1%.4 In recent years, there seems to have been more frequent encounters of FL in the author’s routine diagnostic work and consultation service. In order to clarify the impression of increased incidence of FL, the author has analysed the lymphoma cases diagnosed from January 2005 to December 2007 at Chi-Mei Medical Centre, which had a new branch hospital, 50 km north to the main institution, established in 2004. There are a total of 1864 beds in the two campuses that serve the same population in Tainan in southern Taiwan.

All lymphoma cases were diagnosed and classified according to the 2001 World Health Organization classification of lymphoid neoplasms5 with integration of histopathology, full immunophenotyping, molecular studies (including in situ hybridisation for Epstein-Barr virus, fluorescent in situ hybridisation, and clonality assay with PCR method) whenever indicated, …