Rearrangement of bcl-2 genes in malignant lymphomas in Chinese patients

A Clinicopathologic and Molecular Study of Follicular Lymphoma in Taiwan

BACKGROUND

The clinicopathologic and molecular features of follicular lymphoma (FL) in Taiwan have not been well defined. We conducted a retrospective study including history review, immunohistochemistry, and molecular study for the major breakpoint region (MBR) of t(14;18) and correlated these findings with survival.

PATIENTS AND METHODS

Sixty-five FLs were identified, with a male to female ratio of 1.9:1 and a median age of 63 years (mean, 60 years). Sixty cases (92%) were nodal, 4 (6%) were extranodal, and 1 (2%) was indeterminate. The median ages of the nodal and extranodal cases were 63 years and 44 years, respectively. Disease staging in 59 patients included 15 patients (25%) with stage I disease, 14 (24%) with stage II, 20 (34%) with stage III, and 10 (17%) with stage IV. Forty-four patients received chemotherapy, 2 patients received chemotherapy with palliative radiation therapy, and 13 patients received supportive treatment/observation.

RESULTS

The 5-year survival rate was 52.6%. The cases were classified as grades 1 (n = 27; 42%), 2 (n = 22; 34%), 3A (n = 13; 20%), and 3B (n = 3; 5%). Twenty cases (31%) were positive for MBR, including 19 of 57 (33%) nodal cases and 1 of 4 (25%) primary extanodal FLs. Patients with low-stage disease (stages I/II) had a better survival rate than patients with high-stage disease (III/IV; log-rank test, P = 0.012).

CONCLUSION

This is the largest series of Taiwanese FLs with immunophenotypes and MBR detection rates similar to those of the West. Disease stage was statistically significant with regard to survival. Although the number of extranodal FLs cases was small, the patients were younger, their tumors had lower CD10 expression, and they had more favorable survival rates than patients with nodal disease.

The pattern and frequency of t(14;18) translocation and immunophenotype in Asian follicular lymphoma

AIMS

Follicular lymphoma is frequently associated with t(14;18)(q32;q21) translocation. This study was undertaken to determine the pattern of Bcl-2, CD10 and Bcl-6 expression in relation to t(14;18) translocation in follicular lymphoma from a cohort of a multi-ethnic Asian population.

METHODS AND RESULTS

Sixty-two cases of follicular lymphoma were retrieved for immunohistochemistry, and t(14;18) translocation analysis by polymerase chain reaction and fluorescent in-situ hybridization techniques. Bcl-2 expression was present in 74% of the cases. CD10 expression was also relatively low (61%), with decreasing frequency of expression in high-grade tumours. Bcl-6 protein was expressed in most of the tumours (88%) regardless of the tumour grade. The t(14;18) translocation was detected in 46 cases (74%) with an extremely high rate of t(14;18) translocation in ethnic Indian cases (100%).

CONCLUSION

The frequency of t(14;18) translocation in this series of follicular lymphomas was higher when compared with previous Asian reports, but in accordance with European and North American findings. CD10 expression is strongly associated with a t(14;18) translocation event, but the overall CD10 expression was relatively low, possibly due to the high proportion of high-grade tumours in the series. t(14;18) translocation was not associated with Bcl-2 or Bcl-6 expression.

Pattern of malignant lymphoma in the United Arab Emirates--a histopathologic and immunologic study in 208 native patients

The aim of this study was to analyze the distribution of the various pathologic types of lymphoma in a native Arab population of the United Arab Emirates (UAE). Two hundred and eight patients with malignant lymphoma diagnosed over a 12-year period (1988-1999) were retrospectively studied morphologically and immunohistochemically with a panel of monoclonal antibodies and classified according to the revised European-American classification of lymphoid neoplasms (REAL). Of the 208 patients in the study, 41% had Hodgkin's disease (HD) and 59% had non-Hodgkin's lymphoma (NHL). The distribution of HD showed a predominance of nodular sclerosis and mixed cellularity types. Among NHLs, the most frequent type was diffuse large B cell (59% of all NHLs) followed by the Burkitt's type (13%). The proportion of primary extranodal NHL was 29%. Immunologically, the percentages of NHL with B-cell and T-cell phenotypes were 83 and 11, respectively. When the International Working Formulation was used, 34% of NHLs were classified as high grade, 59% as intermediate grade and only 7% as low-grade lymphomas.

Assessment of prognostic factors in follicular lymphoma patients

Prognostic factors, including clinical, biological, and histological parameters, were assessed for 94 patients with follicular lymphomas at our institute. Follicular lymphomas constituted 7.7% (94/1208) of malignant lymphomas in this study. Eighteen patients were diagnosed with stage I follicular lymphoma, 20 with stage II, 23 with stage III, and 33 with stage IV. The cases of follicular lymphoma were subclassified as: follicular small cleaved cell lymphoma (FSC) in 20 cases, follicular mixed cell lymphoma (FMX) in 59 cases, and follicular large cell lymphoma (FLC) in 15 cases. The patients comprised 49 men and 45 women with a median age of 54 years (range, 25-84 years). The complete response rate was 76.5%, and the median survival time was 13 years. The expected 10-year overall survival and event-free survival rates were 61.9% and 38.2%, respectively. Univariate analysis identified the factors associated with poor survival as elevated serum lactate dehydrogenase (LDH) level (P < .0001), age of >60 (P < .0001), Ann Arbor stage III/IV (P < .01), and Eastern Cooperative Oncology Group performance status (PS) of 2 to 4 (P = .048). Multivariate analysis showed that LDH, age, and PS were independent predictors. After application of the International Prognostic Index (IPI), the 10-year survival rates for the low-risk, low-intermediate risk, high-intermediate risk and high-risk groups were 80.4%, 48.7%, 21.9%, and 0.0%, respectively. The differences among these groups were significant at P < .01. The IPI for aggressive non-Hodgkin's lymphoma was found to be applicable to survival prediction for Japanese follicular lymphoma patients.

Detection of t(14;18) in turkish follicular lymphomas using the polymerase chain reaction

A t(14;18) translocation is closely associated with the follicular lymphoma but is also seen in diffuse B cell lymphomas with a previous history of a follicular lymphoma as well as de novo diffuse lymphomas. Estimation of the frequency of t(14;18) in follicular lymphoma vary widely from 33 to 89%. Furthermore, no extensive data have been published on the frequency of t(14;18) in Turkish cases of follicular lymphoma. Representative tissue blocks from 67 patients with follicular lymphoma, 12 cases of diffuse large B cell lymphomas and 11 cases of reactive hyperplasias were examined for the presence of this translocation using PCR. DNA probes capable of detecting rearrangement at both the major and minor break point regions were employed. We could detect t(14;18) in 46 out of 67 cases (68.7%) of follicular and 25% of diffuse large B cell lymphomas. In follicular lymphomas 64.2% of these break points were at mbr and 4.5% were at the mcr region. Review of the literature showed that comparable results have been obtained previously using molecular techniques. Our data showed that despite the relative infrequency of follicular lymphomas in the Turkish population these lymphomas share a common molecular pathogenesis with involvement of bcl-2 gene and background incidence of such rearrangement is similar in all populations, regardless the incidence of folicular lymphoma.

Geographic variance in the frequency of the t(14;18) translocation in follicular lymphoma: an Israeli series compared to the world

It has been suggested that differences in the frequency of the t(14;18) translocation in follicular lymphoma might explain ethno-geographic variation in the incidence of these tumors. We tested Israeli follicular lymphoma patients for the frequency of the t(14;18) translocation, and reviewed the published literature, comparing the frequency in our series with data from different parts of the world. Tissue specimens from 36 Israeli follicular lymphoma patients were tested for presence of the translocation by PCR amplification of the MBR breakpoint. Twenty-two of the 36 patients (61%) tested positive. A systematic search of the literature yielded 35 papers reporting the frequency of the t(14;18) translocation in follicular lymphoma. We analyzed cytogenetic data and molecular data separately. For each method, data were pooled from all studies within each of three geographical regions - USA, East Asia and Europe. Pooled data from cytogenetic studies show a low frequency of the translocation in the Far East (38%) compared to the USA (71%), with an intermediate frequency found in Europe (61%). Molecular studies show a similar frequency of the translocation in the Far East and Europe, significantly lower than the frequency in pooled data from American studies. The frequency in our Israeli series is relatively high, comparable to that detected in the USA. We suggest that the apparent geographical differences we describe are unlikely to be caused by a difference in the biology of the tumor, and are more likely due to technical and methodological factors. We conclude that it is unlikely that differences in the frequency of the t(14;18) translocation explain the difference in the epidemiology of lymphoma between East and West.

Molecular pathology of low grade malignant lymphomas

During the last ten years the combined efforts of pathologists and molecular biologists have helped define several new lymphoma diagnostic categories. In particular, the recognition of chromosomal translocations which have activated the BCL1 and BCL2 proto-oncogenes have strong associations with specific types of non-Hodgkin's malignant lymphomas such as mantle cell lymphoma and follicular center cell lymphoma, respectively. This review will attempt to summarize our current understanding regarding the contributions of BCL1 and BCL2 to lymphomagenesis and diagnosis.