Clinicopathological features and outcome of late relapses of natural killer cell lymphomas 10-29 years after initial remission

Natural killer (NK)-cell lymphomas are aggressive and relapses occur early. Late relapses are exceptional. Ten relapses 17.5 (11-29) years after first complete remission (CR1) were analyzed. Initial diseases were stage-I (nasal, n = 8; tonsil, n = 1; ileum, n = 1), treated with radiotherapy (n = 6), combined radiotherapy/chemotherapy (n = 3), and chemotherapy (n = 1). Relapse occurred at the same (nasal, n = 6; tonsil, n = 1), adjacent (initial: nasal, relapse: palate; n = 1) or distant (n = 2) sites. Five patients died soon afterwards. Four patients remitted with chemotherapy, two remaining in CR2 (3, 14 years). This series documented the rare late relapses in NK-cell lymphomas, which may still respond to salvage therapy.