Waldeyer's ring marginal zone B cell lymphoma: Are the clinical and prognostic features nodal or extranodal? A study by the Consortium for Improving Survival of Lymphoma (CISL)

There has been controversy surrounding Waldeyer's ring (WR), especially focused on the question of whether it should be regarded as a nodal or an extranodal site. We conducted retrospective analyses of marginal zone B cell lymphomas involving WR (WR-MZLs) to observe their clinical features and prognosis, with specific regard to the nodal-or-extranodal question. A total of 52 patients with histological diagnosis of WR-MZL were retrospectively analyzed. The most common involvement site was the tonsil (40.4 %). Ann Arbor stage III/VI disease was present in 48.1 % (25 of 52). The response rate of the 27 stage I/II patients was 88.9 %, with 21 complete remissions and three partial remissions. The median time to progression (TTP) was 3.7 years (95 % CI 2.5-4.9 years). The estimated 5-year TTP and overall survival rates were 39.4 and 90.5 %, respectively. In a comparison with the historical data regarding extra-WR MALT lymphoma and nodal MZL (N-MZL), MALT lymphoma showed better TTP results than did WR-MZL and N-MZL (P\0.001).