Clinical relevance of bcl-2(MBR)/J(H) rearrangement detected by polymerase chain reaction in the peripheral blood of patients with follicular lymphoma

Detection of BCL2-IGH Using Single-Round PCR Assays

The translocation t(14;18) resulting in fusion of the BCL2 and the immunoglobulin heavy chain genes (BCL2-IGH) is present in 80% to 90% of follicular lymphomas and 20% to 30% of diffuse large B-cell lymphomas. Polymerase chain reaction (PCR) analysis for the translocation products suffers from low analytic specificity. As a result, either nested PCR or probe hybridization is required to aid in the identification of the specific translocation products. These added procedures are undesirable in clinical laboratories because nested procedures increase the possibility of contamination and probe hybridization increases assay turnaround time. To simplify the BCL2-IGH assay procedure, we attempted to eliminate the nonspecific PCR products by optimizing the annealing temperatures of the PCR assays using a gradient thermocycler. We showed that gradually increasing the annealing temperature from 55 degrees C to 67 degrees C significantly enhanced the intensity of the specific PCR products while eliminating the nonspecific ones. We compared the simplified procedure with a PCR-probe hybridization method on 68 patient specimens. The simplified procedure had increased analytic and diagnostic specificities with comparable sensitivities. With significantly improved analytic specificity, one round of PCR is sufficient to detect the BCL2-IGH gene rearrangements without further confirmation.

The differentiation of idiopathic inflammatory pseudotumor from lymphoid tumors of orbit: analysis of 319 cases

PURPOSE

To analyze the clinical, morphologic, immunophenotypic, and molecular genetic differences between idiopathic inflammatory pseudotumor and lymphoid tumors of the orbit.

METHODS

209 patients with IOIP and 110 patients with lymphoid tumors seen between January 1, 1978 and December 31, 1999 in Zhongshan Ophthalmic Center, Sun Yat-sen University were evaluated retrospectively.

RESULTS

More patients with lymphoid tumors had palpable mass than patients with idiopathic orbital inflammatory pseudotumor (IOIP) (P < 0.0001), with the percentage of 90% and 65%, respectively, whereas more patients with IOIP had swollen eyelid, eyelid or conjunctival congestion, pain, retinal folds or hamorrhage, and optic nerve atrophy than patients with lymphoid tumors, with the percentage of 55% and 40% (P = 0.014), 42% and 24% (P = 0.001), 24% and 1% (P < 0.0001), 14% and 4% (P = 0.004), 7% and 2% (P = 0.043), respectively. Ultrasound and computed tomography/magnetic resonance image (CT/MRI) scan usually could not differentiate IOIP from lymphoma. Nearly one third of patients with IOIP could not be easily differentiated pathologically from lymphoid tumor. Immunophenotypic, and molecular genetic analyses can differentiate IOIP from lymphoid tumor based on polyclonal or monoclonal proliferation of lymphocytes with the IOIP being polyclonal and lymphoma monoclonal.

CONCLUSIONS

Idiopathic orbital inflammatory pseudotumor and lymphoid tumor showed distinguishing clinical, morphologic, immunophenotypic, and molecular genetic characteristics.

Molecular remission and non-Hodgkin's lymphoma

Non-Hodgkin's lymphomas are highly sensitive to treatment and complete clinical responses are often achieved. However, disease recurrence is common and is caused by the persistence of malignant lymphoma cells at a level below the limits of detection by conventional assessment such as clinical examination, bone marrow morphology and CT scans. This minimal residual disease can be detected using molecular techniques such as the polymerase chain reaction (PCR), and treatments capable of eliminating minimal residual disease are described as producing molecular remission. Molecular assessment is now commonly used as a measure of outcome in clinical trials of novel therapies for the treatment of lymphoma. The evidence for using molecular remission as a surrogate marker of clinical response in this setting is reviewed and the significance of minimal residual disease in determining prognosis and planning treatment strategies is addressed.

Insights into the molecular pathogenesis of follicular lymphoma arising from analysis of geographic variation

Incidence rates of follicular lymphoma (FL) inexplicably vary markedly between Western and Asian countries. A hallmark of FL is the bcl-2 translocation, characterized by 1 of 2 common breakpoints known as major breakpoint region (MBR) and minor cluster region (mcr). We analyzed previously published data to compare rates of bcl-2 translocation in FL across geographic regions. Available data from the literature suggest that the incidence of bcl-2 in healthy persons in the absence of FL may be as high as 50% in Western and Asian populations. However, in FL our results show that the frequency of bcl-2 positivity was significantly higher for US than for Asian populations (P <.0001). This pattern persisted for MBR and mcr subgroups. We conclude that a significant gradient exists in the bcl-2 frequency between these FL populations. We therefore suggest that the relatively low incidence of FL in Asian populations is caused not by a lower frequency of bcl-2 rearrangements in healthy populations but by distinct molecular pathways developing in different geographic regions that nonetheless culminate in FL, which is morphologically similar but molecularly distinct. Studies demonstrating differences in clinical characteristics according to the presence or absence of bcl-2 rearrangements support this concept. Thus we hypothesize that FL may in fact be a heterogeneous malignancy encompassing entities with distinct molecular pathogenesis and potentially distinct clinical manifestations. If these findings were confirmed in prospective studies, it would imply that different etiologic or genetic factors might influence the development of FL across separate regions.

Absence of the t(14;18) chromosomal translocation in primary cutaneous B-cell lymphoma

BACKGROUND

The t(14;18)(q32;q21) chromosomal translocation is found in the majority of nodal follicular lymphomas and in a lower percentage of systemic high-grade diffuse large B-cell lymphomas. The translocation results in the juxtaposition of the bcl-2 gene on chromosome 18 with the immunoglobulin heavy chain joining region on chromosome 14. Bcl-2 protein prevents apoptosis and the translocation leads to overexpression of a functionally normal Bcl-2 protein that prevents apoptosis of neoplastic cells.

OBJECTIVES

The purpose of our study was to analyse cases of primary cutaneous B-cell lymphoma (PCBCL) for the presence of the t(14;18) translocation and to correlate the results with Bcl-2 expression and histological subtype.

METHODS

Forty-four cutaneous B-cell lymphoid proliferations (36 PCBCL, four follicular B-cell lymphomas with cutaneous presentation and four reactive B-cell infiltrates) were analysed by polymerase chain reaction amplification and polyacrylamide gel electrophoresis using consensus primers for the joining region on the immunoglobulin heavy chain gene in combination with either a primer for the major breakpoint region (MBR) or the minor cluster region (mcr) on chromosome 18.

RESULTS

None of 36 PCBCL analysed demonstrated a t(14;18) translocation; however, three of four systemic follicular B-cell lymphomas presenting in the skin were found to have a translocation in the MBR, which was confirmed by sequence analysis. Correlation with Bcl-2 immunostaining showed that of seven patients with high-grade cutaneous diffuse large B-cell lymphoma, four were Bcl-2 positive but had no evidence of a t(14;18) translocation. In the five cases classified as primary cutaneous follicle centre cell lymphoma, the neoplastic cells within the germinal centres failed to express Bcl-2. However, Bcl-2-positive neoplastic cells were present in all four cases of systemic follicular lymphoma, including the case that did not show a t(14;18) translocation. In all cases of marginal zone lymphoma the marginal zone lymphocytes were Bcl-2 positive.

CONCLUSIONS

These findings indicate that the t(14;18) translocation does not occur in PCBCL, which suggests the involvement of different pathogenetic mechanisms compared with their nodal counterparts. Furthermore, the detection of a t(14;18) translocation in cutaneous B-cell lymphoma should suggest the presence of systemic disease, which underlies the need for exhaustive staging procedures.

Follicular lymphomas--a review of treatment modalities

Follicular lymphoma is the most common low-grade non Hodgkin's lymphoma and represent an homogeneous entity as defined by pathological, molecular and clinical data. This indolent disease is characterised by a slow growth pattern with possible spontaneous regression, is often disseminated but remains incurable with available treatments when disseminated. For localised stages, involved field radiotherapy remains the standard choice but other approaches remain to be investigated. In advanced disease, chemotherapy has been demonstrated to produce high response rates but recent trials with new treatment strategies including interferon and monoclonal antibodies may improve the current situation. In this article, we will review treatment of follicular lymphomas, specially emphasising published phase III trials.

Molecular detection of circulating neoplastic cells in patients with clinically localised gastric and non-gastric mucosa-associated lymphoid tissue lymphoma

BACKGROUND

Unlike other low-grade lymphomas, extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue type usually presents with localised disease.

AIM

To detect peripheral blood lymphoma involvement to establish the incidence of occult lymphoma dissemination.

PATIENTS AND METHODS

In a series of 18 cases, peripheral blood was analysed by polymerase chain reaction, with primers directed to the third-complementarity determining region of the immunoglobulin heavy chain gene.

RESULTS AND CONCLUSION

The presence of circulating neoplastic cells was detected in 21% of clinically localised cases. Moreover lymphoma cells were detected in 2 out of 6 morphologically normal bone marrow specimens. The present data show that, combining morphological and molecular methods, occult dissemination can be found in a large proportion of cases thus stressing the need for careful staging procedures. However, it has still to be clarified whether the presence of polymerase chain reaction-detectable circulating lymphoma cells can influence the outcome of mucosa-associated lymphoid tissue lymphoma patients submitted to antibiotic treatment (for gastric localisation) or local therapy (surgery or radiation, for non-gastric tumours).

Lack of CD95/FAS gene somatic mutations in extranodal, nodal and splenic marginal zone B cell lymphomas

Germline CD95 (also known as FAS, APT1 and APO1) gene mutations have been associated with benign lymphoproliferative diseases and autoimmune processes. Somatic mutations have been reported in human tumours, including lymphomas. Since marginal zone B cell lymphomas usually arise in a background of chronic inflammation, often of autoimmune origin, we searched for CD95 gene mutations in an unselected series of marginal zone B cell lymphomas. The CD95/FAS full coding region, comprising exon-intron junctions, was amplified from genomic DNA by polymerase chain reaction (PCR) in 10 separate reactions. PCR products were analysed by single-strand conformation polymorphism (SSCP) and visualised by silver staining. Bands exhibiting an altered electrophoretic mobility were sequenced. Twenty-seven cases of marginal zone B cell lymphomas of whom fresh or frozen tumour material was available (18 extranodal, five splenic and four nodal) were studied. Previously described silent polymorphisms in exons 7 (C836T) and 3 (T416C) were detected in 42% and in 19% of the cases, respectively. One silent T-to-A substitution at bp 431, within exon 3, was found in one case. Our results did not reveal the presence of CD95 somatic mutations in unselected cases of marginal zone B cell lymphomas. On the basis of our data, we cannot rule out that other genes coding for proteins involved in the CD95-induced apoptotic pathway might be altered. However, this pathway does not seem to play an important role in the pathogenesis of these lymphoma subtypes.

Clonality assessment in blood of patients with mantle cell lymphoma

The presence of circulating neoplastic cells at diagnosis was assessed in the blood of patients presenting with mantle cell lymphoma (MCL) to determine the feasibility of a diagnostic molecular assay. Blood samples from 16 patients with pathologically reviewed MCL were analysed for the t(11;14)(q13;q32) translocation by the polymerase chain reaction (PCR): 7 (44%) were found positive. The remaining cases were examined by PCR for the presence of circulating neoplastic B-cells by amplifying the third complementarity region (CDR3) of immunoglobulin heavy chain genes and the immunoglobulin light kappa chain deletion rearrangements. A further 7 (44%) patients showed the presence of clonal lymphoma cells, leaving only 2 (12%) of cases negative for circulating lymphomatous cells. This study suggests that there is a high incidence of lymphoma cells in the blood of patients presenting with MCL. PCR for these clonal cells may be diagnostically useful.