Clinicopathologic and genotypic study of extranodal nasal-type natural killer/T-cell lymphoma and natural killer precursor lymphoma among Koreans

Background: This study aimed to define genotypic profile and to describe the clinicopathologic features of nasal-type natural killer (NK)/T-cell lymphoma of nasal and extranasal origin and NK precursor lymphoma.

Methods: NK/T-cell lymphomas from the upper aerodigestive tract (n = 45), skin (n = 2), gastrointestinal tract (n = 3), and soft tissue (n = 2) and NK precursor neoplasms (n = 3) were studied. Immunophenotype was analyzed by immunohistochemistry and flow cytometry. In situ hybridization with EBER 1/2 RNA probes was performed. T-Cell Receptor (TCR)-gamma gene rearrangement was analyzed by seminested polymerase chain reaction with heteroduplex analysis. Overall survival rate was correlated with clinicopathologic parameters and compared by Wilcoxon test.

Results: Clonal TCR-gamma gene rearrangement was detected in 3 of 31 upper aerodigestive and 1 of 2 skin tumors. When immunostained using paraffin embedded tissue, 6 upper aerodigestive lymphomas were negative for CD56 in which 4 cases lacked clonal TCR gene rearrangement. Epstein-Barr virus (EBV) mRNA was detected in 33 upper aerodigestive tumors including 26 of 29 nasal tumors (90%), and 7 of 10 extranasal tumors (70%). There was no histologic, immunophenotypic, or genotypic differences according to the lineage and EBV association in upper aerodigestive lymphomas. Among the patients with upper aerodigestive tumors, overall 1-year survival rate was 41%, and correlated well with the stage (P < 0.05) but not with the size of tumor cells, EBV status, and lineage (P > 0.05). Median survival rate of lymphomas from other sites excluding upper aerodigestive tract was not significantly different from that of upper aerodigestive lymphomas with same stage (P > 0.05). Unlike nasal-type NK/T-cell lymphomas, NK precursor lymphoma involved the bone marrow and lymph nodes at initial presentation or in the course of disease. Tumor cells were positive for TdT in all and myeloid markers in two. TCR gene rearrangement was germ line.

Conclusions: Most upper aerodigestive nasal-type NK/T-cell lymphomas among Koreans are genotypically of NK derivation and few belong to T lineage. Presence or absence of EBV has no significant correlation with the histologic changes and the lineage of these lymphomas.