OBJECTIVETo analyze the clinicopathologic features of extranodal NK/T cell lymphoma, nasal type (ENKTCL-N), to explore the expression of NK cell-associated receptors in ENKTCL-N and the relationship with prognosis, and to establish a prognostic model.

METHODSOne hundred and twenty-six cases of ENKTCL-N were selected from the files of the Department of Pathology, West China Hospital of Sichuan University. The relevant clinical and follow-up data were collected, and the histopathology was reviewed. All specimens were stained immunohistochemically for CD16, ICAM-1 and LFA-1. RT-PCR was used to detect the expression of CD94, NKG2 and KIR. The relationship between the prognosis of ENKTCL-N, clinical features, histopathological characteristics and expression of these markers were also analyzed.

RESULTSENKTCL-N mainly occurred in middle-age and young patients (median age, 41 years). The male to female ratio was 3.2:1. Sites more commonly involved were the nose and upper aerodigestive tract whereas those for the non-nasal type were the skin and gut. Only six cases involved two or more extranodal sites. Most (86.5%, 109/126) of the patients were in clinical stages I/II. The tumors showed predominately medium-sized tumor cells and large-sized tumor cells accounted for only 9.5% (12/126). Coagulative necrosis was present in all cases. The expression rates of CD56, CD16, CD94, LFA-1 and ICAM-1 were 82.6% (95/115), 15.1% (19/126), 55.4% (41/74), 40.5% (51/126) and 0, respectively. The expression rate of NKG2 receptor was 90.5% (67/74) overall. NKG2 receptor expression was independent of CD94. The overall expression rate of KIR receptor was 33.8% (25/74) and KIR receptor restriction was not detected in 20.8% (5/24) of the cases. Follow-up data was available in all patients, with median and average survival time being 15 months and 20.2 months, respectively. Survival analysis showed that prognostic factors included the gender, age, disease type, extranodal involvement, stage, the expression of CD16, LFA-1 and CD94. Cox's proportional hazard regression analysis revealed four factors, age, involved site, stage and CD16 expression, were independent prognostic factors.

CONCLUSIONSThe age, disease type, stage and CD16 expression are independent prognostic factors. Establishment of a prognostic model based on the above four factors can be more accurate in the prognostication of ENKTCL-N. The differences in the clinical features, prognosis, and expression of NK cell-associated receptors are obvious between nasal NK-cell lymphoma and non-nasal NK-cell lymphoma.