OBJECTIVETo study the NK/T-cell lymphoma, search for a more efficacious and simpler method and establish a standard guideline for distinguishing the NK-like T-cell lymphoma from the NK-cell lymphoma.

METHODSThirty-four NK or T-cell lymphomas from the upper aerodigestive tract (n = 22), skin (n = 2), gastrointestinal (GI) tract (n = 2), lymph nodes (n = 7), and other sites (n = 1) were studied. Immunophenotype was analyzed by immunohistochemistry. In situ hybridization with EBER 1/2 RNA probes was performed. T-cell receptor (TCR)-beta and -gamma gene rearrangement was analyzed by polymerase chain reaction (PCR).

RESULTSEighteen cases were positive for CD(56) and 16 for TIA-1 in 34 lymphomas cases. All tumor cells in the skin cases were positive for Ki-67. Epstein-Barr virus (EBV) mRNA was detected in 12 upper aerodigestive tumors including 9 of 12 nasal and 3 extranasal tumors. EBER was also detected in 1 of 2 skin lymphomas and both of the 2 GI lymphomas. Clonal TCR-beta and -gamma gene rearrangement was detected in 2 of 22 upper aerodigestive, all of the skin and GI lymphomas, and 6 of 9 nodal and other site lymphomas.

CONCLUSIONMost upper aerodigestive NK/T-cell lymphomas are genotypically NK derivation, and a few belong to T lineage. However, NK-like T-cell lymphomas more frequently seen in skin and GI tract. Nodal NK-cell lymphoma are quite rare. These two kinds of lymphomas can only be diagnosed with additional immunohistochemical markers, EBER detection by ISH, TCR gene rearrangement or NK-cell receptors (NKRs) RNA detection. Detection of TCR rearrangement remains the important standard for the diagnosis of T-cell lymphoma.