Nasal natural killer/T-cell
lymphoma (N-NK/T-L) is prevalent in China. To further characterize this
neoplasm, 36 cases of N-NK/T-L from 304 cases of
malignant lymphomas in the north China area were investigated by histopathology, immunophenotyping, and genomic analysis of c-kit, in comparison with 11 cases of
B-cell lymphoma (BCL) at the same region and 5 cases of nodal
peripheral T-cell lymphoma (PTCL) (unspecified). Histopathologically, N-NK/T-L was characterized by coagulative
necrosis, inflammatory background, and angiodestructive growth pattern. In 36 cases of N-NK/T-L, 27 cases (75.0%) were stained for CD45RO and 25 (72.2%) for CD3epsilon. Thirty cases (83.3%) were positive for
T-cell intracellular antigen-1, 22 (61.1%) for
granzyme B, 18 (50.0%) for CD56, and 11 (30.6%) for CD30, whereas none was positive for CD117. All 5 cases of PTCL displayed positive staining for CD45RO and
T-cell intracellular antigen-1, 3 cases for CD3epsilon, but only 1 case for
granzyme B. All 11 BCLs presented positive staining for CD20 and CD79a but negative for other
antibodies. A significant relationship was observed between neoplastic cells pleomorphism and
granzyme B expression (P < .05). Despite the fact that all cases were negative for CD117 staining, genomic sequences of c-kit 11 and exon 17 sequencing showed that 8 (26%) of 31 cases N-NK/T-L proved to contain genomic mutations, including 4 cases in exon 11 and 4 in exon 17. For the control group, only 1 (9%) of 11 BCLs and 1 (20%) of 5 cases of PTCL were detected to harbor mutations in exon 11. All mutations detected in 3 groups were missense by base substitution, and codes 571, 572, and 821 were hot spots. The results suggested that, in addition to histological features and routine immunophenotyping,
granzyme B expression should be a more reliable marker in correct diagnosis of N-NK/T-L, and genetic analysis of c-kit mutation should be helpful in the diagnosis of this
tumor.