Malignant lymphomas in Waldeyer's ring in Asian countries: Association with histologic types and Epstein-Barr virus.

The present study examines clinicopathologic findings and their association with the Epstein-Barr virus (EBV) in Waldeyer's ring lymphomas (WRLs) from Indonesia (91 cases), P.R. China (31 cases), Korea (101 cases) and Japan (61 cases). Waldeyer's ring (WR) was categorized into upper and lower parts comprising the pharyngeal and tubal tonsils (upper WR) or palatine and lingual tonsils (lower WR), respectively. Diffuse large B-cell lymphoma (DLBCL) pre-dominated in the lower WR in all countries at a frequency of 78.9-100%. Natural killer/T-cell lymphoma (NKTCL) was predominant in the upper WR in China, Korea and Japan at a frequency of 50-62.5%, while in Indonesia it occcurred at a frequency of less than 10%. On the whole, patients with NKTCL were significantly younger (median 43 years) than those with DLBCL (57 years). Patients with DLBCL in the lower WR were significantly younger in Indonesia (median 50 years) than in China (63 years) or Japan (69 years). The percentage of EBV-positive cases was much higher in NKTCL (78.6-100%) than in DLBCL (2.2-6%). This study evaluates the differences between East and Southeast Asian countries in terms of histologic type and age distribution in WRLs categorized by the location of the lesions in WR.