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Summary. Natural killer (NK)/T-cell lymphoma is a special subtype of rare malignant lymphoma that is more prevalent in Asia than in America and Europe. This newly characterized haemato-lymphoid malignancy is highly aggressive and frequently present in nasal and upper aerodigestive sites. Several studies have reported the commonly deleted region of chromosome 6q21–25 in this particular type of lymphoma. To refine the smallest region of overlapping (SRO) deletion for localization of potential tumour suppressor (TS) genes, we performed loss of heterozygosity (LOH) and homozygosity mapping of deletion (HOMOD) analyses on 37 nasal and nasal-type NK/T-cell lymphoma patients using a panel of 25 microsatellite markers, covering the 6q21–q25 region. In all patients studied, LOH was detected in eight (89%) paired-sample patients, while hemizygous deletion was detected in three (11%) single-sample patients. Combination of the LOH and HOMOD results defined a distinct 3 Mb SRO on chromosome 6q25. Quantitative multiplex polymerase chain reaction analysis of 10 sequence-tagged sites further refined the putative TS-gene-containing region to a 2·6 Mb interval between TIAM2 and SNX9. Eighteen known genes/Unigene clusters and 25 hypothetical genes are located within this 2·6 Mb region, but none are previously identified TS genes. These results provide a framework for future positional cloning of novel TS gene(s) at 6q25.2–q25.3.

Lymphoproliferative diseases of large granular lymphocytes (LDGL) may arise from either CD3+ T cells or CD3− natural killer (NK) cells. LDGL with clonal proliferation of large granular lymphoeytes (LGL) is defined as LGL leukaemia. The number of patients with NK-LGL leukaemia reported is limited and the pathogenesis of the disease is not yet clear. From 1991 to 1998 six patients with cytogenetically proved clonal disease of NK-LGL were identified in our institute. All were seropositive for Epstein-Barr virus (EBV). EBV RNA or DNA could be detected in LGL from four patients by EBV in situ hybridization or Southern blot analysis. Most patients ran an aggressive clinical course and five died of the disease. Nonrandom clonal chromosomal abnormalities, including duplication of 1q, rearrangement at 3q and loss of chromosomes Y, 13 or 10, were noted in the six patients from this study and in eight from the literature. The implications of these recurrent cytogenetic aberrations in the development and progression of the disease deserve further studies.

The long-term outcome of 22 children treated with etoposide-containing regimens for haemophagocytic syndrome (HS) were longitudinally studied; none of them had a family history of the disease. All patients received etoposide-containing (150 mg/m2/d) regimens, combined, in 16 cases, with intravenous immunoglobulin (IVIG) and prednisolone. Complete remission (CR) was achieved in 12 patients, partial remission in seven, and early mortality occurred in three. Of the 12 CR patients, only four remain alive and disease-free, with a median follow-up of 47.4 months; one CR patient died due to infection and the remaining seven had relapsed diseases. Three patients with a partial response or with relapsed disease progressed to T-cell lymphoma, characterized, in the two cases tested, by clonal chromosomal abnormalities. Epstein-Barr virus (EBV) infection was implicated in disease pathogenesis in 15/22 patients. The overall survival was 45.5%, 40.9% and 40.9% at 1, 3 and 5 years, respectively, and disease-free survival for CR patients at these same times was 45.5%, 36.4% and 36.4%. The etoposide-containing regimen would appear to be an effective initial therapeutic option for childhood HS. However, in view of the frequency of partial remissions and relapsed disease, a more intensive chemotherapy or bone marrow transplantation should be applied. The progression to EBV-containing T-cell lymphoma in three patients is consistent with the previous observation that EBV-associated HS is a potentially malignant disease.

Nasal T/natural killer (NK) cell lymphoma is a distinct clinicopathologic entity which is more prevalent in Asia than in America and Europe. The clonal nature of the infiltrating lymphoid cells is difficult to demonstrate because of the lack of immunologic markers for clonality and the absence of clonal T-cell receptor gene rearrangement in most cases. In this study, clonal chromosomal abnormalities were detected in the tumour cells from four patients with nasal T/NK cell lymphoma. This finding provided direct evidence for clonality of the disease. Moreover, nonrandom cytogenetic abnormalities, including isochromosome for the short arm (p) of chromosome 6, isochromosome for the long arm (q) of chromosome 1, partial deletion of 6q, and aberrations at 11q, were disclosed. Isochromosome 6p was the sole structural abnormality in one patient, which may be a pathognomonic change in nasal lymphoma.

Haemophagocytic syndrome (HS) is frequently observed in Epstein-Barr virus-associated peripheral T-cell lymphoma (EBV-PTCL) and represents a major cause of death. In this communication we have further analysed the spectrum of HS in 12 patients with EBV-PTCL. The patients could be divided into three groups according to the time of onset of HS during the clinical course of PTCL. Group I patients (four cases) had HS as the initial clinical manifestation. All four patients were initially suspected to have malignant histiocytosis (MH) but a MH-like PTCL was later diagnosed. Group II patients (six cases) developed HS at the time of lymphoma relapse. Four of them belonged to the angioinvasive type PTCL. Group III patients (two cases) developed HS at clinical remission; both were angioinvasive type PTCL. Nine patients had serological evidence suggesting active EBV infection. The clinical course after the onset of HS was generally fulminant in each group with a median survival of only 44d despite combination chemotherapy and/or empirical therapy with high-dose immunoglobulin and corticosteroids in six patients. In conclusion, HS represents a severe complication of EBV-PTCL. Although most patients develop HS at a time of active lymphoma, the syndrome may occur when the lymphoma is in remission. Because of the poor outcome, early diagnosis and a new modality of treatment for HS associated with EBV-PTCL should be pursued in future.

Haemophagocytic lymphohistiocytosis (HLH) is a fatal haematological disorder with diverse aetiology. This prospective study was undertaken to characterize HLH cases in Vietnamese children. Clinical and laboratory data, genetic analyses and outcome of the HLH patients were analysed. A total of 33 patients were enrolled from March 2007 to December 2008, with a median age of 3 years. Mutations of the SH2D1A (SAP) and PRF1 genes were detected in one patient, respectively. The virus association was high, up to 63.6% (21/33), including Epstein-Barr virus (19/33), cytomegalovirus (2/33) and dengue virus (2/33). Five patients had malignant lymphoma and two had autoimmune diseases. Twenty-eight patients were treated according to the HLH-2004 protocol. The first response rate was 64.3% (18/28), with an early death rate of 35.7% (10/28). High levels of interferon-gamma, interleukin-10, MIG and interferon-inducible protein-10 (IP-10) were associated with early mortality (P < 0.05). Reactivation among the responders was high (9/18) and the uneventful resolution was low (3/18) after a median follow-up of 35 weeks. In conclusion, the majority of HLH cases are associated with virus infections in Vietnamese children. Familial HLH is rare. The frequent reactivation and high mortality demands a more appropriate therapeutic regimen in tropical areas like Vietnam.

The Epstein-Barr virus (EBV), or human herpesvirus-6 (HHV-6) associated haemophagocytic lymphohistiocytosis, has been found prevalent in Taiwan; it affects previously healthy children and is always fatal when treated only supportively. Recognition of the underlying pathogenesis for this disease prompted adoption of an immunomodulatory regimen of intravenous immunoglobulin (IVIG) and/or etoposide on 17 such patients treated between 1990 and 1993. Remarkable improvement in patients' prognoses was demonstrated. Eight patients are still alive with a median follow-up of 1 year and 2 months post-treatment. Both IVIG and etoposide had positive immunomodulation effects such as alleviation of fever and normalization of haematological and hepatic parameters. Sustained complete response was obtained in two of nine cases of EBV-associated diseases treated with IVIG only. EBV transcripts became undetectable after etoposide and/or IVIG treatment without antiviral agents. Etoposide given by split-doses schedule appeared to be superior to conventional three-consecutive-days schedule for both remission induction and disease-free survival. Our preliminary trial apparently provides a promising improvement in the treatment of this previously fatal disease. IVIG or etoposide is effective in reversing the process of lymphohistiocytic dysregulation resulting from virus infection of immune cells in this syndrome and probably helps hosts to control active virus replication in certain cases, through immunomodulation.

Summary The virus-associated T cell leukaemias/lymphomas are characterized by a poor prognosis primarily because of the rapid emergence of drug resistance which may lead to failure of subsequent chemotherapy. We report here a case of Epstein-Barr virus-associated T cell lymphoma which relapsed soon after chemotherapy and radiotherapy. The neoplastic cells of the relapsed tumour expressed high levels of multi-drug resistance gene (mdr 1)-related P-glycoprotein and glutathione-S-transferase-π, both of which were absent in the pre-chemotherapy tumour tissues. Empirical treatment with oral 13-cis-retinoic acid (RA) was then given with subsequent complete disappearance of the tumour. The therapeutic effect of KA appears to act through an apoptotic process. In accordance with our previous report of a successful salvage of a refractory Ki-1 large cell lymphoma. RA appears to be a potentially useful drug for some specific type T-cell lymphomas.