EXTRANODAL NASAL/NASAL TYPE NK/T CELL LYMPHOMA (ENKL) (the most common and well characterized NK-cell neoplasmref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9, ref10, ref11, ref12). Although the cell of origin is a NK cell in 80% of cases, particularly in patients in the Far East, central and South America and in native Americans, 10-30% of cases arise from cytolytic T cells (NK-like T cells that express CD56 and TIA-1; gd > aß typeref1, ref2, ref3). Hence, the designation nasal and nasal type NK/T-cell lymphoma. It should be noted that 35-55% of nasal tumors overall have a B cell phenotyperef1, ref2. Lymphomas involving the sinuses without nasal lymphoma are predominantly diffuse large B-cell lymphoma (DLBCL), whereas lymphomas involving the nasal cavity alone are predominantly NK/T-cell lymphomasref.
Epidemiology : more commonly occurs in Asia and Latin America. The disease occurs more commonly in males, and the median age is 5055 yearsref1, ref2 (Chan JK. Peripheral T-cell and NK-cell neoplasms: an integrated approach to diagnosis. Mod. Pathol. 1999;12:17799)
Aetiology : HHV-4 / EBV is present in the majority (80-100%) of nasal NK/T-cell lymphomas and less often in nasal type NK/T-cell lymphomas (15-40% or more in some series)ref1, ref2, ref3, ref4. Of 7 cases in Chile, 6 cases were of type 1 EBV and wildtype F at BamHI-F region, 4 cases were type "i" EBV at BamHI-W1/I1 region and XhoI wildtype was found in 2 and XhoI loss in 4 cases, respectively. Co-segregation analysis of BamHI-W1/I1 region and XhoI restriction site demonstrate that the novel recombinant strain type "i" / XhoI was loss in 3 cases and type "i" / XhoI wildtype strain in 1 caseref. In situ hybridization for EBER was detected in 41 out of 42 cases (97.6%)ref. EBER-1 ISH should be performed on BM specimens of patients with nasal NK/T-cell lymphoma to identify the presence of EBER-1 positive cells, which appears to carry a poor prognosis. Whether or not the EBER-1 positive cells in the BM of nasal NK/T-cell lymphoma patients are true tumor cells requires further studyref. Sometimes preceded by EBV antigenemiaref
Pathogenesis : a significantly higher proportion of the tumors (27%), compared to previous studies, demonstrated monoclonal TcRg gene rearrangement. There was, however, no difference in survival or clinicopathologic features between the true NK-cell tumors and their T-cell counterparts. Overexpression of p53 was present in 40% of the cases, but no significant difference in survival rate was detected in patients with p53 overexpression and there was no association between p53 overexpression with large cell morphology, and advanced stage of diseaseref. EBV-encoded RNA promotes growth of EBV-infected T cells through IL-9 inductionref
Symptoms & signs : nasal obstruction, nasal discharge, and epistaxis. The disease may present with facial swelling or midfacial/destructive disease and was formerly called lethal midline granuloma. Nasal NK/T lymphoma is localized stage I/II in 80% of patients at diagnosis but can disseminate early to skin, gastrointestinal tract, testis, orbit and CNS. Bone marrow is involved in < 10% of patients with nasal-type NK/T cell lymphoma at initial diagnosisref. Few cases occur primarily in areas other than the nose (e.g. duodenumref, testisref1, ref2, lungref or endometriumref). In a series, 31 out of 42 cases presented in the upper aerodigestive tract. The other sites of involvement included gastrointestinal tract, skin, soft tissue, testis, liver, spleen, bone marrow and brain. The tumors displayed characteristic morphologic featuresref.
Laboratory examinations : Therapy : there was no difference in survival between involved-field radiotherapy and chemoradiotherapy (RT + CHOP or COPBLAM-V) in angiocentric T-cell and NK/T-cell lymphoma, nasal typeref. The addition of anthracycline-containing chemotherapy to radiotherapy does not appear to confer any survival benefit in Stage IE patientsref Associated diagnosis : Castleman diseaseref
Prognosis is variable with long-term survival of 20-35%ref1, ref2, primarily in stage I, non-bulky disease. Some studies have reported survivals above this range (up to 80%); however, inclusion of CD56 and EBV cases or lack of reporting of immunophenotyping may have resulted in the inclusion of more favorable lymphomas. Systemic progression is usually fatalref1, ref2. Nasal-type NK/T cell lymphoma has a worse prognosis that those originating in the nasal region due to disseminated extranodal disease, including skin, gastrointestinal tract, soft tissue, and testisref. Patients with cutaneous only involvement have a better survivalref. Only 20% of patients have stage I diseaseref. Despite anthracycline therapy, median survival is < 1 yearref. The only significant adverse prognostic factor identified was an IPI > 2ref. Anyway after a median follow-up duration of 51.2 months, 5-year OS rate in 262 patients was 49.5%. Prognostic factors for survival were "B" symptoms (P = .0003; relative risk, 2.202; 95% CI, 1.446 to 3.353), stage (P = .0006; relative risk, 2.366; 95% CI, 1.462 to 3.828), lactate dehydrogenase (LDH) level (P = .0005; relative risk, 2.278; 95% CI, 1.442 to 3.598), and regional lymph nodes (P = .0044; relative risk, 1.546; 95% CI, 1.009 to 2.367). Of 262 patients, 219 had complete information on four parameters. We identified four different risk groups: group 1, no adverse factor; group 2, one factor; group 3, two factors; and group 4, three or four factors. The new model showed a superior prognostic discrimination as compared with the International Prognostic Index (IPI). Notably, the distribution of patients was balanced when a new model was adopted (group 1, 27%; group 2, 31%; group 3, 20%; group 4, 22%), whereas 81% of patients were categorized as low or low-intermediate risks using IPIref. Ann Arbor staging system did not predict CR, OS, or DFS but IPI did have predictive power with regard to survival outcome. Local tumor invasiveness (LTI) (defined as bony invasion or destruction or tumor invasion of the skin) is the most important prognostic factor in predicting low probability of CR and reduced OS and DFS in nasal stage IE/IIE NTCLref. Categorisation of the 2 subtypes of NK/T cell lymphoma as follows:
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