High-grade B-cell non-Hodgkin Lymphoma Research Articles

A role for surgery in primary pancreatic B-cell lymphoma: a case report

IntroductionPrimary pancreatic lymphoma is a very rare but manageable malignant tumour which may be clinically confused as a pancreatic carcinoma. This case report demonstrates the value of surgical resection in the management of pancreatic lymphoma.Case presentationWe report a case of a 65-year-old man who was admitted with obstructive jaundice, vague upper abdominal pain and weight loss. Ultrasonography and computed tomography showed a mass at the head of the pancreas which was compressing the bile duct. The patient underwent pancreaticoduodenectomy. Histopathologic and immunohistochemical assessment of the pancreatic lesion established the diagnosis of a diffuse, extranodal, high-grade B-cell non-Hodgkin's lymphoma. Several doses of chemotherapy were administered postoperatively and at present the disease remains in remission.ConclusionThe favourable outcome for this patient and a thorough review of the literature underline the important role that operative resection may have in the management of at least the early stage of primary pancreatic lymphoma.

C-MYC translocation in t(14;18) positive follicular lymphoma at presentation: An adverse prognostic indicator?

Follicular lymphoma (FL) is a common subtype of low grade B-cell non-Hodgkin lymphoma (NHL). Although this form of lymphoma often pursues an indolent course, in some cases it may behave in a more aggressive manner. Clinical and histological parameters have been shown to correlate with an adverse prognosis but a number of cytogenetic abnormalities may also be associated with aggressive disease. Although, the t(14;18) in itself does not affect outcome in cases of FL, secondary abnormalities that occur in a complex polyploid karyotype may identify cases with a poor prognosis. It is unusual to find both t(14;18) and C-MYC translocation in the same tumour; those cases in which it has been described include examples of high-grade B-cell NHL (either de novo or transformed FL) or B-cell acute lymphoblastic lymphoma. In this report, three cases of FL are described in which both t(14;18) and a C-MYC translocation were identified at presentation. We also summarize four further cases from the literature. This is a small series but one which raises the possibility that the presence of a C-MYC translocations at presentation may identify a particularly aggressive subtype of FL. Further studies are required to investigate the true incidence of this aberration, the impact on C-MYC regulation, clinical course and response to treatment.

AIDS defining lymphomas in the era of highly active antiretroviral therapy (HAART) – An African perspective

The intermediate to high grade B-cell non-Hodgkin lymphomas are now one of three malignant AIDS defining conditions. The others being Kaposi’s sarcoma and cervical carcinoma. While co-infection with oncogenic agents including the human herpes 8 or Epstein-Barr virus offer targets in preventive treatment strategies for these AIDS defining lymphomas (ADL), administration of highly active antiretroviral therapy leading to immune reconstitution permits use of standard or even high-dose cytotoxic drug regimens with curative intent. It is not certain whether this should be done concomitantly or sequentially. Additional benefit may derive from infusional or high-dose chemotherapy regimens depending on the histological subtype while use of monoclonal antibodies such as rituximab or immunohaematopoietic stem cell transplantation needs to be further evaluated within controlled studies. Socio-economic considerations have an impact especially in resource limited settings while availability of tools for appropriate geno–phenotypic diagnosis and immunological monitoring such as the CD4 cell count will play an important role in the risk stratification as well as disease management. While it is generally accepted that the impact of HAART has an overall benefit both in incidence and treatment outcome in ADL, the expanded access to HAART programs are falling short of all targets in Africa. Accordingly focus is given to some of these controversies, including epidemiology, pathogenesis, clinical features, therapeutic options and ethical considerations.

Emergency Pancreatoduodenectomy (Whipple Procedure) for Massive Upper Gastrointestinal Bleeding Caused by a Diffuse B-Cell Lymphoma of the Duodenum: Report of a Case

We herein report a rare case of a massive upper gastrointestinal (GI) bleeding, caused by high-grade diffuse B-cell lymphoma of the duodenum, secondary to immunoproliferative small intestinal disease (IPSID) and treated with an emergency partial pancreatoduodenectomy. A 42-year-old man was admitted to our hospital because of hematemesis. Upper GI endoscopy was unrevealing because of the copious bleeding. Initially, the patient underwent conservative treatment, thus resulting in the temporary cessation of the bleeding. Later, the hemorrhage massively relapsed. An urgent abdominal ultrasound raised the suspicion of a large, possibly bleeding, neoplasm of the duodenum, which was finally confirmed by abdominal computed tomography. The patient underwent an emergency laparotomy, during which a partial pancreatoduodenectomy was performed (Whipple procedure). Histologically, the tumor was a high-grade B-cell lymphoma of the duodenum. The nearby small intestinal mucosa was suggestive of IPSID. A massive upper GI hemorrhage from a high-grade B-cell non-Hodgkin lymphoma of the duodenum, which develops secondary to IPSID, is a very rare clinical demonstration of this disease. Our case is one of the few reports in the English literature, for which the Whipple procedure has been performed as a curative treatment.

Inactivation of the p16 Cyclin-Dependent Kinase Inhibitor in High-Grade Canine Non-Hodgkin's T-Cell Lymphoma

The significance of p16/Rb tumor suppressor pathway inactivation in T-cell non-Hodgkin's lymphoma (NHL) remains incompletely understood. We used naturally occurring canine NHL to test the hypothesis that p16 inactivation has specific pathologic correlates. Forty-eight samples (22 T-cell NHL and 26 B-cell NHL) were included. As applicable, metaphase- or array-based comparative genomic hybridization, Southern blotting, promoter methylation, and Rb phosphorylation were used to determine the presence, expression, and activity of p16. Fisher's exact test was used to test for significance. Deletion of p16 (or loss of dog chromosome 11) was restricted to high-grade T-cell NHL (lymphoblastic T-cell lymphoma and peripheral T-cell lymphoma, not otherwise specified). These were characterized by a concomitant increase of tumor cells with Rb phosphorylation at canonical CDK4 sites. Rb phosphorylation also was seen in high-grade B-cell NHL (diffuse large B-cell lymphoma and Burkitt-type lymphoma), but in those cases, it appeared to be associated with c-Myc overexpression. The data show that p16 deletion or inactivation occurs almost exclusively in high-grade T-cell NHL; however, alternative pathways can generate functional phenotypes of Rb deficiency in low-grade T-cell NHL and in high-grade B-cell NHL. Both morphologic classification according to World Health Organization criteria and assessment of Rb phosphorylation are prognostically valuable parameters for canine NHL.

Resection alone in 58 children with limited stage, lymphocyte‐predominant Hodgkin lymphoma–experience from the European network group on pediatric Hodgkin lymphoma

Lymphocyte-predominant Hodgkin lymphoma (LPHL) is a rare, CD20-positive, good prognostic lymphoma in children. Patients with early-stage LPHL who underwent successful surgical lymph node resection alone have been reported. To clarify the optimum treatment strategy in children, European study groups were asked to report their experience of surgery alone used in the treatment of pediatric LPHL. Data from 58 patients were collected by the French Society for Pediatric Cancers, the German-Austrian Pediatric Study Group/German Society of Pediatric Oncology and Hematology (Germany), and the Children's Cancer and Leukaemia Group (United Kingdom). In total, there were 50 boys and 8 girls, and the median age was 11 years (age range, 4-17 years). Fifty-four patients had stage IA disease, 2 patients had stage IIA disease, and 2 patients had stage IIIA disease. With a median follow-up of 43 months (range, 2-202 months), the overall survival rate was 100%, and the progression-free survival (PFS) rate was 57%. Fifty-one of 58 patients achieved complete remission (CR) after surgery. In the CR group, the overall PFS rate was 67% (95% confidence interval, 51-82%). All seven patients who had residual disease after initial surgery developed recurrences (P = .003). Among 18 patients with stage IA LPHL who developed recurrent disease, 11 patients had local recurrences, and 7 patients recurred in stage IIA. One patient with stage IIIA disease presented with high-grade B-cell non-Hodgkin lymphoma at 10 years of follow-up. When complete resection was achieved, a substantial proportion of patients with surgically treated, early-stage LPHL experienced long-term remission and actually may have been cured.

Multicolor Fluorescence In Situ Hybridization (M-FISH) in Highly Aggressive B-Cell Lymphomas with 8q24/MYC Involvement Revealed the Heterogeneity of 13q Abnormalities with Unexpected Partial Gains.

Chromosomal translocations involving the MYC oncogene (8q24) are known to occur in Burkitt lymphomas/leukemias (BL) but also in 5–30% of diffuse large B-cell lymphomas which are usually highly aggressive (8q24 DLBCL). Two recent conventional cytogenetics (CC) studies showed that secondary chromosomal abnormalities have a negative prognostic impact, especially13q abnormalities (frequently described as a deletion and usually associated with a complex karyotype, i.e. > 3 chromosomal alterations), mainly in childhood mature B-cell lymphomas, and in a less extent 7q, 3q, 22q and chromosome 17. M-FISH was applied to 120 (74% adults and 26% children) high grade B-cell non-Hodgkin lymphomas (86% BL, 14% 8q24 DLBCL) carrying MYC rearrangement and complex karyotype and/or 13q abnormality in order to find recurrent and/or cryptic chromosomal alterations. Abnormal metaphases were available in 96 (80%) cases. We described ‘new' (not seen in CC) chromosomal rearrangements in 50 (52%) cases, refined those seen by CC in 28 (29%) cases and confirmed CC abnormalities in 18 (19%) cases.M-FISH allowed to characterize 55 structural 13q abnormalities in 42 patients (21 ‘new' alterations): 24 der(13q) leading to partial del(13q) and partial gain of different partner chromosomes [mainly 1q or 7q], 15 del(13q) [of 2 minimal regions : q14 & q31q34], 13 gains (only 2 seen by CC) and 3 balanced translocations.Combined results of CC and M-FISH showed that the most frequent abnormalities among patients with complex karyotype involved 1q, 7q, Xq, 3q, 18q, 6q, 17p and chromosome 22 (excluding 8q24 translocations). 79 1q abnormalities were detected in 54 patients (26 % ‘new'): mostly gains (minimal amplified region: q22q31) due to unbalanced translocations with chromosomes 13, 22, 7 (59%) or duplications (25%). 55 partial 7q gains were observed in 42 patients (22% ‘new'), mostly +7 or unbalanced translocations with 13q, 6q or 1q. The other most common abnormalities were: t(14;18) in 8q24 DLBCL, del(6q), der(3q) with various partners leading to partial loss of 3q, monosomy 17 or del(17p) and numerical changes of chromosomes 22 (monosomy) and X.In conclusion, this study confirms the contribution of M-FISH in refining CC results in highly aggressive 8q24 B-cell lymphomas:‘new' rearrangements were identified especially in 1q (leading to partial 1q gains), 18q, 6q (leading to partial 6q deletions), 13q ;partial 13q gains were underestimated by CC and both 13q deletions and gains were more heterogeneous than expected.We are characterizing these prognostic additional chromosomal abnormalities with SNP-CHIPS 50K array (Affymetrix) to look for candidate genes and/or cellular pathways involved in Burkitt lymphomagenesis in cooperation with oncogenic effect of MYC. °on behalf of the GFCH (Groupe Francophone de Cytogénétique Hématologique) and the BCG-Ho (Belgian Cytogenetic Group of Hematology and Oncology).

Linfoma primario de cavidades

Primary effusion lymphoma is a rare high-grade B-cell non-Hodgkin's lymphoma associated with human herpesvirus 8 (HHV-8) infection, and is mostly observed in the course of HIV infection (AIDS). The prognosis is poor, with reported median survival time shorter than 6 months. We present a case of a 65-year-old man, with prior unknown origin chronic hepatopathy, chronic hemolytic anaemia, and ascites. Biopsy of peritoneum showed a primary effusion lymphoma. The patient died two months later.

AIDS-related malignancies: changing epidemiology and the impact of highly active antiretroviral therapy

Three cancers in people with HIV denote an AIDS diagnosis: Kaposi's sarcoma, high-grade B-cell non-Hodgkin's lymphoma and invasive cervical cancer. In addition a number of other cancers occur at increased frequency in this population group but are not AIDS-defining illnesses. This review discusses the impact of highly active antiretroviral therapy on the epidemiology and outcome of AIDS-defining cancers. The incidence of both Kaposi's sarcoma and non-Hodgkin's lymphoma has declined in the era of highly active antiretroviral therapy and the outcome of both tumours has improved. Moreover, highly active antiretroviral therapy alone produces a response in a majority of antiretroviral-naïve patients with Kaposi's sarcoma. In contrast, highly active antiretroviral therapy has had little impact on the incidence of human papilloma virus-associated tumours (cervical and anal cancer) in people with HIV, although it may improve survival by reducing opportunistic infection deaths. As people with HIV live longer with highly active antiretroviral therapy, an increased incidence of other non AIDS-defining cancers that have no known association with oncogenic infections is becoming apparent. For those with access to highly active antiretroviral therapy, the good news from the AIDS-defining cancers - particularly Kaposi's sarcoma and non-Hodgkin's lymphoma - may be balanced by the increasing numbers of non AIDS-defining cancers.

Primary pulmonary AIDS-related lymphoma

Extranodal involvement is common in lymphomas associated with human immunodeficiency virus infection (HIV) and acquired immunodeficiency syndrome (AIDS). However, primary pulmonary AIDS-related non-Hodgkin's lymphoma is very rare and only few reports were published in the medical literature. Clinical presentation is nonspecific, with "B" and respiratory symptoms. Also, patients were with advanced immunodeficiency at the time of diagnosis. Generally, chest radiography showed peripheral nodules or cavitary masses. Primary pulmonary lymphoma associated with AIDS is generally a high-grade B-cell non-Hodgkin lymphoma and Epstein-Barr virus is strongly associated with the pathogenesis of these tumors. We report a patient with AIDS and primary pulmonary lymphoma which clinical presentation was a total atelectasis of the left lung.

Prognostic Factors and Outcome of Human Herpesvirus 8–Associated Primary Effusion Lymphoma in Patients With AIDS

Primary effusion lymphoma (PEL) is a rare high-grade B-cell non-Hodgkin's lymphoma associated with Kaposi sarcoma-associated herpesvirus/human herpesvirus 8 (KSHV/HHV-8) infection, and is mostly observed in the course of HIV infection. The prognosis is poor, with reported median survival time shorter than 6 months. To date, no prognostic factor has been identified in this subset of lymphoma. We describe here a large series of HIV-infected patients with PEL, including 28 cases diagnosed in six centers during an 11-year time period. Prognosis analysis was performed using a Cox proportional hazard regression model. Statistically significant covariates were further analyzed in a forward, stepwise multivariate model. After a median follow-up of 3.8 years (range, 10 months to 10.8 years), nine patients (32%) were still alive, and eight of them remained progression free. The median survival was 6.2 months, and the 1-year overall survival rate was 39.3%. Fourteen patients (50%) achieved complete remission, with a 1-year disease-free survival rate at 78.6%. In a multivariate analysis, only a performance status more than 2 (hazard ratio, 5.84; 95% CI, 1.76 to 19.33) and the absence of highly active antiretroviral therapy (HAART) before PEL diagnosis (hazard ratio, 3.26; 95% CI, 1.14 to 9.34) were found to be independent predictors for shorter survival. Based on a retrospective series of 28 patients, two prognostic factors were identified as being independently associated with impaired clinical outcome in HIV-related PEL--(1) a poor performance status and (2) the absence of HAART before PEL diagnosis.

Treatment of primary cutaneous B-cell lymphoma with rituximab

Rituximab is a genetically engineered antibody directed against the CD20 antigen. Intravenous administration of rituximab has been used for the treatment of patients with low-, intermediate-, and high-grade B-cell non-Hodgkin's lymphomas and is a registered treatment modality for this indication. Treatment of primary cutaneous B-cell lymphoma (CBCL) with intralesionally or systemically administered rituximab has been described only in a few cases. Our purpose was to assess the efficacy of rituximab in the treatment of CBCL. We performed a retrospective study on 9 patients with CBCL who were treated with intralesional or systemic administration of rituximab. Two patients treated with systemic rituximab achieved complete remission. Complete remission could be observed in 6 of 7 patients after 1 to 8 cycles of intralesional treatment with rituximab. In one patient one of two lesions showed a partial remission after 4 cycles of treatment, whereas the second showed complete remission. A local recurrence was observed in one patient after 27 months of follow-up and in two patients recurrences developed at other body sites after 12 and 14 months of follow-up. No severe side effect occurred except for slight pain during intralesional injection. Rituximab therapy is a well-tolerated and effective treatment for primary CBCL. In comparison to intravenous administration, intralesional application of the drug allows the use of lower dosages. Intralesional therapy with rituximab deserves further investigation and comparison to systemic administration of the drug in controlled multicenter studies.

Flow cytometric immunophenotyping including Bcl-2 detection on fine needle aspirates in the diagnosis of reactive lymphadenopathy and non-Hodgkin's lymphoma

Fine-needle aspiration (FNA) with immunophenotyping by immunocytochemistry (IC) on cytospins has recently received increased consideration in the diagnosis of lymphoma. The aim of our study was to establish the diagnostic value of a four-color flow cytometric (FCM) panel, including cytoplasmic Bcl-2, in cytologic diagnosis of malignant non-Hodgkin's lymphoma (NHL) and reactive lymphoid hyperplasia (RH). We investigated 424 FNAs from 396 patients. FCM panel included lambda/kappa/CD19/CD5, CD23/CD10/CD20/CD19, CD4/CD7/CD8/CD3 and Bcl-2/CD10/CD19/CD3 in fluorescein isothiocyanate, phycoerythrin, and peridinin chlorophyll protein or a tandem conjugate of R-phycoerythrin and indodicarbocyanine and allophycocyanin. Bcl-2 expression was evaluated separately for gated B and T cells. In 97% of 172 RH samples, FCM was concordant with the diagnosis. FCM gave correct immunologic diagnosis in 95% of low-grade B-cell NHLs, 78% of high-grade B-cell NHLs, and 53% of T-cell lymphomas. Malignant B cells had higher Bcl-2 expression than did reactive B and T cells. This helped to establish a correct diagnosis especially in cases where no clear-cut monoclonality could be shown by kappa/lambda staining or where there was no expression of surface light chain. The highest Bcl-2 expression was found in follicular lymphomas. Our FCM panel allowed precise classification of NHL in FNA material in 89.5% of all samples. Bcl-2 staining can be recommended for primary differentiation between reactive hyperplasia and NHL.

Prognostic Factors and Outcome of Human Herpesvirus 8 (KSHV/HHV-8)-Associated Primary Effusion Lymphoma (PEL) in Patients with AIDS.

Primary effusion lymphoma (PEL) is a rare high-grade B-cell non-Hodgkin lymphoma associated with Kaposi sarcoma-associated Herpesvirus/Human Herpesvirus 8 (KSHV/HHV-8) infection, and mostly observed in the course of HIV infection. The prognosis is poor with reported median survival time shorter than 6 months. To date, no prognostic factor has been identified in this subset of lymphoma. We described here the largest series of HIV-infected patients with PEL, including 30 cases diagnosed in six French centers over a 15-year time period. Prognosis analysis was performed using a Cox proportional hazard regression model. Statistically significant covariates were further analyzed in a forward, stepwise multivariate model. After a median follow-up of 3.2 years (range, 10 months-8.2 years), 9 patients (30%) were still alive, and 8 of them remained progression free. The overall median survival was 5.5 months and the 1-year overall survival rate was 36.7%. Fourteen patients (47%) achieved complete remission, with a 1-year disease-free survival rate at 78.6%. In multivariate analysis, only a performance status > 2 [hazard ratio 6.27, 95% confidence intervals (CI),1.91–20.58] and the absence of highly active antiretroviral therapy (HAART) before PEL diagnosis [hazard ratio 0.28, 95% CI, 0.10–0.77] were found to be independent predictors for shorter survival. Based on a retrospective series of 30 patients, two prognostic factors were identified as being independently associated with impaired clinical outcome in HIV-related PEL, (i) a poor performance status and (ii) the absence of HAART prior to PEL diagnosis.

Immunoglobulin Gene Rearrangement of Lymphoid Malignancies: Application of the PCR Technique to Formalin-Fixed, Paraffin-Embedded Tissues

Every B-lymphocyte carries a unique sequence of the immunoglobulin heavy chain (IgH) gene, which serves as a marker for tumor cells derived from clonal B-lymphocyte expansion. Southern blot analysis for IgH gene rearrangement is not suitable for small biopsies and formalin-fixed, paraffin-embedded tissues. We aimed to assess the application of PCR techniques to demonstrate clonal IgH gene rearrangement in B-cell non-Hodgkin's lymphoma (B-NHL). A series including 119 B-NHL, 10 T-cell NHL, 6 reactive lymphoid hyperplasia, and 15 non-lymphoid malignancies were examined. DNA was extracted from paraffin-embedded tissues by proteinase K digestion. A semi-nested PCR amplification targeting two framework regions (Fr2A and Fr3A) and the joining region (JH) of the variable gene segment of the IgH gene was performed. Clonal IgH gene rearrangement was detected in 30% and 63% of B-NHL with Fr2A and Fr3A assays, respectively, and 74.8% when both assays were combined. Clonal IgH gene rearrangement was not demonstrated in any of the reactive lymphoid hyperplasia and non-lymphoid malignancies. However, 20.0% of the T-NHL showed clonal IgH gene rearrangement. Differences were noted among different subtypes of B-NHL. Clonal IgH gene rearrangement was detected in all of the low-grade B-NHL, except follicular lymphoma. High-grade B-NHL generated heterogeneous results.

Sporadic Burkitt's lymphoma of the head and neck in the pediatric population

Burkitt's lymphoma (BL) is one of the fastest growing malignancies in the pediatric population in the United States. BL is a high-grade B-cell Non-Hodgkin's lymphoma (NHL) which exists in endemic, sporadic, and human immunodeficiency-associated subtypes. The African, or endemic, variant usually involves the maxilla and other facial bones while head and neck manifestations in non-endemic BL are rare. We present three unusual present ations of sporadic BL stemming from Waldeyer's ring and the orbit. The clinical and pathologic features of BL are reviewed.

Lack of HCV infection in malignant cells refutes the hypothesis of a direct transforming action of the virus in the pathogenesis of HCV-associated B-cell NHLs.

Preliminary evidence suggests that hepatitis C virus (HCV) might play a pathogenetic role in autoimmune-related, non-malignant B-cell lymphoproliferation, as well as in a subset of B-cell non-Hodgkin's lymphomas (NHLs). With regard to the mechanism(s) by which HCV might favor B-cell expansion and malignant transformation, most data support an indirect pathogenetic role of the virus as an exogenous trigger. A direct oncogenetic role of HCV by direct cell infection and deregulation has only been hypothesized on the basis of the lymphotropism of the virus. In this study we investigated the possible HCV infection of NHL B cells by means of sensitive and quantitative polymerase chain reaction (PCR) on affinity-purified neoplastic cells, and by HCV-specific immunohistochemistry and in situ hybridization. HCV infection of neoplastic B cells was documented in only three cases, namely the low-grade B-cell NHLs that arose in the course of mixed cryoglobulinemia syndrome (MC). HCV infection, below one viral genome per cell, was detectable only by PCR. All the remaining low-grade (one case) and high-grade B-cell NHLs (two cases) were HCV uninfected. Previous immunoglobulin gene analyses were consistent with an antigen-driven B-cell lymphoproliferation in the studied cases. Overall, our data are consistent with an indirect oncogenetic role of HCV in B-cell lymphomagenesis as an exogenous trigger. Infection of B cells by HCV appears possible in some NHL subsets, but the implications remain unknown.

AIDS-related non-Hodgkin's lymphoma: Clinico-pathological characteristics and therapeutic strategies (Review)

High-grade B-cell non-Hodgkin's lymphoma (NHL), a diagnostic disease for the acquired immunodeficiency syndrome (AIDS), is a late manifestation of HIV infection and is generally related to severe lymphopenia. We reviewed the main clinico-pathological features of this disease and analysed its pathogenetic mechanisms with potential therapeutic implications.

Coexpression of BMI-1 and EZH2 polycomb-group proteins is associated with cycling cells and degree of malignancy in B-cell non-Hodgkin lymphoma

Polycomb-group (PcG) proteins, such as BMI-1 and EZH2, form multimeric gene-repressing complexes involved in axial patterning, hematopoiesis, and cell cycle regulation. In addition, BMI-1 is involved in experimental lymphomagenesis. Little is known about its role in human lymphomagenesis. Here, BMI-1 and EZH2 expression patterns are analyzed in a variety of B-cell non-Hodgkin lymphomas (B-NHLs), including small lymphocytic lymphoma, follicular lymphoma, large B-cell lymphoma, mantle-cell lymphoma, and Burkitt lymphoma. In contrast to the mutually exclusive pattern of BMI-1 and EZH2 in reactive follicles, the neoplastic cells in B-NHLs of intermediate- and high-grade malignancy showed strong coexpression of BMI-1 and EZH2. This pattern overlapped with the expression of Mib-1/Ki-67, a marker for proliferation. Neoplastic cells in B-NHL of low-grade malignancy were either BMI-1(low)/EZH2(+) (neoplastic centroblasts) or BMI-1(low)EZH2(-) (neoplastic centrocytes). These observations show that low-, intermediate-, and high grade B-NHLs are associated with increased coexpression of the BMI-1 and EZH2 PcG proteins, whose normal expression pattern is mutually exclusive. This expression pattern is probably caused by a failure to down-regulate BMI-1 in dividing neoplastic cells, because BMI-1 expression is absent from normal dividing B cells. These observations are in agreement with findings in studies of Bmi-1 transgenic mice. The extent of BMI-1/EZH2 coexpression correlated with clinical grade and the presence of Mib-1/Ki-67 expression, suggesting that the irregular expression of BMI-1 and EZH2 is an early event in the formation of B-NHL. This points to a role for abnormal PcG expression in human lymphomagenesis. (Blood. 2001;97:3896-3901)

Reproductive factors and risk of intermediate- or high-grade B-Cell non-Hodgkin's lymphoma in women.

The incidence rates of non-Hodgkin's lymphoma (NHL) unrelated to human immunodeficiency virus infection are lower for women than for men; yet, few factors have been identified that may account for this difference in risk. NHL is difficult to study epidemiologically because this disorder represents a group of malignancies that differ in terms of morphologic presentation, immunologic features, genetic characteristics, prognosis, and etiology. We conducted a population-based case-control study in women to determine whether reproductive factors or hormonal exposures might be related to the risk of high- or intermediate-grade B-cell NHL. We interviewed 177 female residents of Los Angeles County who were diagnosed with high- or intermediate-grade B-cell NHL between 1989 and 1992; each case patient was individually matched on age and race to a control subject who lived in her neighborhood. Women who had used oral contraceptives had significantly lower risk of intermediate- or high-grade NHL (multivariate odds ratio [OR] = 0.47; 95% confidence interval [CI], 0.26 to 0.86) than women who had never used these compounds. Among parous women, those who had used lactation suppressants (which contain high levels of estrogen) had significantly lower risk of NHL (multivariate OR = 0.50; 95% CI, 0.29 to 0.85) than unexposed women. Postmenopausal women had a somewhat greater risk of NHL than premenopausal women, whereas those postmenopausal women who had used hormone replacement therapy (HRT) (primarily estrogen) had somewhat lower risk than those who had not used HRT. Exogenous estrogens seem to have a protective effect on the risk of high- and intermediate-grade B-cell NHL. Although the mechanisms for such protection are not known, alterations in immune reactivity, cytokine expression, or B-cell modulation may play a role.