Objective: The aim of this study was to investigate the frequency and clinicopathologic features of nasopharyngeal extranodal NK/T-cell lymphoma, nasal type (NKTCL), as well as DNA sequence variation of Epstein-Barr virus (EBV) in neoplastic cells harboring in NKTCLs from Guangzhou district.
Materials and methods: The clinical data of 18 unselected consecutive nasopharyngeal NKTCLs in one institution were reviewed retrospectively. Immunohistochemical staining and EBV-encoded RNAs (EBERs) in situ hybridization were applied. DNA extraction, polymerase chain reaction (PCR), nested PCR, and sequencing for analyzing the C-terminal and N-terminal regions of LMP1 gene as well as BamHI F fragment of EBV were applied in 16 available samples.
Results: NKTCLs accounted for 69.2% (18/26) of nasopharyngeal T- and NK-cell lineage non-Hodgkin lymphomas. In all, 10 out of 18 patients (55.56%) had cervical lymph node(s) involvement. The serum anti-EBV antibody level was elevated (VCA-IgA titer ≥1:40) in 6 of 12 available patients. Two major immunophenotypic subtypes, namely, TIA-1+/EBERs+/CD56+ (10 cases) and TIA-1+/EBERs+/CD56- (8 cases) could be recognized. Genotyping analysis revealed that 10 out of 13 cases (76.9%) of NKTCL were harbored with del-LMP1 [del-LMP1 (Gly335) variant 7 cases, del-LMP1 (Asp335) variant 3 cases]. XhoI-loss was shown in 8/11 cases (72.73%). BamHI "f" variant of Bam F fragment was shown only in 4/14 cases (28.57%).The most common combination was del-LMP1 (Gly335)/ XhoI-loss/F (6/9, 66.7%).
Conclusions: The majority of nasopharyngeal T- and NK-cell lymphomas are NKTCL in Guangzhou district. The patients often have involvement of cervical lymph node(s) and an elevated level of serum anti-EBV antibodies. The CD56 expression rate seems lower than that found in sinonasal NKTCL. The most common EBV variant harboring in nasopharyngeal NKTCL seems somewhat different from that harboring in nasopharyngeal carcinoma in Guangzhou.