BCL2 gene abnormalities define distinct clinical subsets of follicular lymphoma

Correlation of t(14;18) translocation breakpoint site with clinical characteristics in follicular lymphoma

BACKGROUND

t(14;18)(q32;q21) translocation is an important genetic feature of follicular lymphoma resulting in antiapoptotic B-cell lymphoma 2 (BCL2) protein overexpression. On chromosome 18 breakpoint-site variation is high but does not affect BCL2. Breakpoint most commonly occurs at major breakpoint region (MBR) but may happen at minor cluster region (mcr) and between MBR and mcr at 3'MBR and 5'mcr. The aim of this study was to analyze the correlation of t(14;18)(q32;q21) breakpoint site with clinical characteristics in follicular lymphoma.

PATIENTS AND METHODS

We included patients diagnosed with follicular lymphoma who received at least 1 cycle of systemic treatment and had the t(14;18)(q32;q21) translocation detected by polymerase chain reaction (PCR) at MBR, mcr or 3'MBR prior to first treatment. Among patients with different breakpoints, sex, age, disease grade, stage, B-symptoms, follicular lymphoma international prognostic index (FLIPI), presence of bulky disease, progression free survival and overall survival were compared.

RESULTS

Of 84 patients, 63 had breakpoint at MBR, 17 at mcr and 4 at 3'MBR. At diagnosis, the MBR group had a significantly lower disease stage than the mcr group. Although not significant, in the MBR group we found a higher progression-free survival (PFS) and overall survival (OS), lower grade, age, FLIPI, and less B-symptoms.

CONCLUSIONS

Compared to patients with mcr breakpoint, those with MBR breakpoint seem to be characterised by more favourable clinical characteristics. However, a larger study would be required to support our observation.

Cell-Permeable Bak BH3 Peptide Induces Chemosensitization of Hematologic Malignant Cells

Hematologic malignancies such as leukemias and lymphomas are among the leading causes of pediatric cancer death worldwide, and although survival rates have improved with conventional treatments, the development of drug-resistant cancer cells may lead to patient relapse and limited possibilities of a cure. Drug-resistant cancer cells in these hematologic neoplasms are induced by overexpression of the antiapoptotic B-cell lymphoma 2 (Bcl-2) protein families, such as Bcl-_XL, Bcl-2, and Mcl-1. We have previously shown that peptides from the BH3 domain of the proapoptotic Bax protein that also belongs to the Bcl-2 family may antagonize the antiapoptotic activity of the Bcl-2 family proteins, restore apoptosis, and induce chemosensitization of tumor cells. Furthermore, cell-permeable Bax BH3 peptides also elicit antitumor activity and extend survival in a murine xenograft model of human B non-Hodgkin's lymphoma. However, the activity of the BH3 peptides of the proapoptotic Bak protein of the Bcl-2 family against these hematologic malignant cells requires further characterization. In this study, we report the ability of the cell-permeable Bak BH3 peptide to restore apoptosis and induce chemosensitization of acute lymphoblastic leukemia and non-Hodgkin's lymphoma cell lines, and this event is enhanced with the coadministration of cell-permeable Bax BH3 peptide and represents an attractive approach to improve the patient outcomes with relapsed or refractory hematological malignant cells.

Molecular and clinical progress in follicular lymphoma lacking the t(14;18) translocation (Review)

Although the majority of patients with follicular lymphoma (FL) harbor the t(14;18)(q32;q21) IGH/BCL2 gene rearrangement that leads to the overexpression of BCL2 protein, approximately 20% of FL cases lack t(14;18)(q32;q21). It is considered that BCL2 overexpression underscores the development of the majority of cases of FL and their transformation to more aggressive lymphoma [known as transformed FL (tFL)]. However, FL cases lacking the t(14;18)(q32;q21) translocation exhibit symptoms analogous to their t(14;18)‑positive counterparts. An important goal of recent research on FL has been to clarify the distinctions between the two different forms of FL. Numerous studies have shed light onto the genetic and molecular features of t(14;18)‑negative FL and the related clinical manifestations. In this review, we summarize the current knowledge of t(14;18)‑negative FL occurring in the lymph nodes with an emphasis on the underlying molecular and clinical features. In addition, novel treatment directions are discussed.

Live Attenuated Salmonella enterica Expressing and Releasing Cell-Permeable Bax BH3 Peptide Through the MisL Autotransporter System Elicits Antitumor Activity in a Murine Xenograft Model of Human B Non-hodgkin's Lymphoma

The survival of patients with non-Hodgkin's lymphoma (NHL) has substantially improved with current treatments. Nevertheless, the appearance of drug-resistant cancer cells leads to patient relapse. It is therefore necessary to find new antitumor therapies that can completely eradicate transformed cells. Chemotherapy-resistant cancer cells are characterized by the overexpression of members of the anti-apoptotic B-cell lymphoma 2 (Bcl-2) protein family, such as Bcl-_XL, Bcl-2, and Mcl-1. We have recently shown that peptides derived from the BH3 domain of the pro-apoptotic Bax protein may antagonize the anti-apoptotic activity of the Bcl-2 family proteins, restore apoptosis, and induce chemosensitization of tumor cells. In this study, we investigated the feasibility of releasing this peptide into the tumor microenvironment using live attenuated Salmonella enterica, which has proven to be an ally in cancer therapy due to its high affinity for tumor tissue, its ability to activate the innate and adaptive antitumor immune responses, and its potential use as a delivery system of heterologous molecules. Thus, we expressed and released the cell-permeable Bax BH3 peptide from the surface of Salmonella enterica serovar Typhimurium SL3261 through the MisL autotransporter system. We demonstrated that this recombinant bacterium significantly decreased the viability and increased the apoptosis of Ramos cells, a human B NHL cell line. Indeed, the intravenous administration of this recombinant Salmonella enterica elicited antitumor activity and extended survival in a xenograft NHL murine model. This antitumor activity was mediated by apoptosis and an inflammatory response. Our approach may represent an eventual alternative to treat relapsing or refractory NHL.

Diagnostic value of STMN1, LMO2, HGAL, AID expression and 1p36 chromosomal abnormalities in primary cutaneous B cell lymphomas

AIMS

Distinction between primary cutaneous follicular lymphoma (PCFL) and primary cutaneous marginal zone lymphoma (PCMZL) is challenging, as clear-cut immunophenotypical and cytogenetic criteria to segregate both entities are lacking.

METHODS AND RESULTS

To characterize PCFL and PCMZL more clearly and to define criteria helpful for the differential diagnosis, we compared expression of immunohistochemical markers [LIM-only transcription factor 2 (LMO2), human germinal centre-associated lymphoma (HGAL), stathmin 1 (STMN1), activation-induced cytidine deaminase (AID), myeloid cell nuclear differentiation antigen (MNDA)] and the presence of cytogenetic abnormalities described previously in nodal follicular lymphoma [B cell lymphoma 2 (BCL2) and BCL6 breaks, 1p36 chromosomal region deletion (del 1p36)] in a series of 48 cutaneous follicular and marginal zone lymphomas [cutaneous follicular lymphoma (CFL) and cutaneous marginal zone lymphoma (CMZL)]. Immunostaining for STMN1, LMO2, HGAL and AID allowed the distinction between CFL and CMZL, and STMN1 was the most sensitive marker (100% CFL, 0% CMZL). LMO2, HGAL and AID were positive in 93.2%, 82.1% and 86.2% CFL (all CMZL-negative). MNDA was expressed in both entities without significant difference (10.3% CFL, 30.8% CMZL, P = 0.18). BCL2, BCL6 breaks and the del 1p36 were present in 16.7%, 10.7% and 18.5% CFL and no CMZL. Finally, three and 29 CFL were reclassified as secondary cutaneous follicular lymphomas (SCFL) and PCFL without significant differences concerning phenotypical and cytogenetic features. BCL2, BCL6 breaks and the del 1p36 were present in 11.1%, 8% and 16.7% PCFL and did not impact the prognosis.

CONCLUSION

LMO2, HGAL, STMN1 and AID, but not MNDA, are discriminant for the recognition between CFL and CMZL. BCL2, BCL6 rearrangements and the del 1p36 have a role in the pathogenesis of PCFL, the latest being the most common alteration.

Primary Cutaneous Follicle Center Lymphomas Expressing BCL2 Protein Frequently Harbor BCL2 Gene Break and May Present 1p36 Deletion: A Study of 20 Cases

The classification of cutaneous follicular lymphoma (CFL) into primary cutaneous follicle center lymphoma (PCFCL) or secondary cutaneous follicular lymphoma (SCFL) is challenging. SCFL is suspected when tumor cells express BCL2 protein, reflecting a BCL2 translocation. However, BCL2 expression is difficult to assess in CFLs because of numerous BCL2+ reactive T cells. To investigate these issues and to further characterize PCFCL, we studied a series of 25 CFLs without any extracutaneous disease at diagnosis, selected on the basis of BCL2 protein expression using 2 BCL2 antibodies (clones 124 and E17) and BOB1/BCL2 double immunostaining. All cases were studied using interphase fluorescence in situ hybridization with BCL2, BCL6, IGH, IGK, IGL breakapart, IGH-BCL2 fusion, and 1p36/1q25 dual-color probes. Nineteen CFLs were BCL2 positive, and 6 were negative. After a medium follow-up of 24 (6 to 96) months, 5 cases were reclassified as SCFL and were excluded from a part of our analyses. Among BCL2+ PCFCLs, 60% (9/15) demonstrated a BCL2 break. BCL2-break-positive cases had a tendency to occur in the head and neck and showed the classical phenotype of nodal follicular lymphoma (CD10+, BCL6+, BCL2+, STMN+) compared with BCL2-break-negative PCFCLs. Del 1p36 was observed in 1 PCFCL. No significant clinical differences were observed between BCL2+ or BCL2- PCFCL. In conclusion, we show that a subset of PCFCLs harbor similar genetic alterations, as observed in nodal follicular lymphomas, including BCL2 breaks and 1p36 deletion. As BCL2 protein expression is usually associated with the presence of a BCL2 translocation, fluorescence in situ hybridization should be performed to confirm this hypothesis.

Diagnostic and prognostic value of BCL2 rearrangement in 53 patients with follicular lymphoma presenting as primary skin lesions

OBJECTIVES

To study the diagnostic value of BCL2 rearrangement in follicle center lymphoma (FCL) presenting as primary skin lesions, evaluate its prevalence and the prognostic value in primary cutaneous FCL (PCFCL), and assess prognostic factors in PCFCL.

METHODS

Fifty-three patients with a cutaneous presentation of FCL without a history of nodal lymphoma were selected retrospectively. Clinical and histologic data were collected together with staging and follow-up data. A fluorescence in situ hybridization (FISH) test for BCL2 split probes was performed on skin biopsy specimens.

RESULTS

Initial staging procedures identified 47 PCFCLs and six cases of secondary skin involvement of FCL (SSIFCL). FISH detected seven cases carrying a BCL2 rearrangement: four (8.5%) of 47 PCFCLs and three (50%) of six SSIFCLs. These seven cases coexpressed BCL2 and CD10. In PCFCL, cutaneous relapse rate was 42.6%. A small/medium centrocytic cell population was associated with a higher probability of skin relapse in univariate (P = .008) and multivariate (P = .028) analysis, and BCL2 rearrangement detection was associated with secondary extracutaneous spreading (P = .05).

CONCLUSIONS

We observed that BCL2 rearrangement in PCFCL is rare, associated with initial positivity of staging (diagnostic value) or with secondary extracutaneous spreading (prognostic value). In selected cases with BCL2-CD10 coexpression, FISH testing could detect patients with poor outcome and require closer monitoring.

Pathology of extra-nodal non Hodgkin lymphomas

In the management of extra-nodal lymphomas it is important to determine whether the tumour has disseminated and whether lymph nodes are involved. Some extra-nodal lymphomas may be the result of random spread of nodal lymphoma. Specific homing, however, determines the site of many extra-nodal lymphomas, as exemplified by cutaneous T-cell lymphomas, which seem to be derived from skin-homing T-cells and mucosa-associated lymphoid tissue lymphomas that show features of the mucosal immune system. Enteropathy-associated T-cell lymphoma is derived from mucosal T-cells in patients with coeliac disease. Immunological sanctuary accounts for the localisation of primary brain, eye and testicular lymphoma. Mantle cell lymphoma frequently causes tumours in the gastrointestinal tract. Random biopsies have shown that a high proportion of patients with this lymphoma have extensive occult involvement of the gastrointestinal tract at the time of first diagnosis. Follicular lymphoma occurs at both nodal and extra-nodal sites, but uncommonly at both sites at the same time. Extra-nodal follicular lymphomas frequently lack t(14;18)(q32;q21) and do not express bcl-2, which are characteristics of the nodal disease. At extra-nodal sites, follicular lymphoma is more likely to be curable than nodal follicular lymphoma. The behaviour of extra-nodal lymphomas cannot be assumed to follow that of their nodal counterparts.

Pathology, pathogenesis and molecular genetics of follicular NHL

Follicular lymphoma (FL) is a germinal centre-derived indolent B-cell lymphoma representing the second most common Non Hodgkin lymphoma in the Western world. This chapter focuses on the pathology of FL and summarizes the current knowledge about genetic and molecular features that are relevant for the pathogenesis of this neoplasm. The translocation t(14;18) is present in approximately 90% of FL leading to the upregulation of the anti-apoptotic protein BCL2, that may constitute a promising molecular target for therapeutic approaches. FL lacking the t(14;18) also exist, and B-cells carrying the t(14;18) can be detected in a subset of healthy individuals. In addition to the t(14;18), secondary genetic alterations are present in most FL and, more recently, deeper insights into the methylation and microRNA expression patterns in the tumour cells have been gained. The tumour microenvironment appears to be particularly important for the biology and the clinical course of FL.

Translocation t(14;18)/IGH-BCL2 in gastrointestinal follicular lymphoma: correlation with clinicopathologic features in 48 patients

BACKGROUND

Chromosomal translocation t(14;18)(q32;q21) involving the immunoglobulin heavy chain gene (IGH) and the BCL2 gene (t[14;18][q32;q21]/IGH-BCL2) is present in 60% to 90% of nodal follicular lymphomas. To the authors' knowledge, the prevalence and clinical significance of this translocation have not been examined previously in gastrointestinal follicular lymphomas.

METHODS

Clinicopathologic and molecular features were investigated in 48 patients who had gastrointestinal follicular lymphoma. The site of involvement was the duodenum in 54% of patients, the jejunum in 52%, the ileum in 52%, the stomach in 29%, and the colorectum in 15%. The presence of the t(14;18)/IGH-BCL2 translocation was detected by interphase fluorescence in situ hybridization.

RESULTS

Treatment modalities included surgical resection (n = 16), rituximab plus chemotherapy (n = 13), rituximab alone (n = 6), antibiotics (n = 5), and watchful waiting (n = 8). Complete remission (CR) of lymphoma was achieved in 31 patients (65%). The overall survival and event-free survival rates after 5 years were 93% and 68%, respectively. The t(14;18)/IGH-BCL2 was detected in 39 patients (81%). The involvement of multiple sites (69% vs 0%), manifestation of the lymphomatous polyposis type (72% vs 22%), and histologic grade 1 or 2 tumors (92% vs 56%) were more frequent in the t(14;18)-positive group than in the negative group. In addition, the CR rate was lower in the t(14;18)-positive group than in the negative group (56% vs 100%; P = .0179), and a trend was observed toward poorer event-free survival in the positive group (P = .089).

CONCLUSIONS

The t(14;18)/IGH-BCL2 chromosomal translocation occurred frequently in gastrointestinal follicular lymphomas. The current results indicated that this translocation may be a predictor of an adverse clinical course.

Recent Advances in Follicular Lymphoma: Pediatric, Extranodal, and Follicular Lymphoma in Situ

Follicular lymphoma is a relatively common B-cell lymphoma composed of follicle center B lymphocytes. Follicular lymphomas occurring in the pediatric population and in some extranodal sites exhibit particular clinicopathologic features and clinical behavior that are often distinct from adult nodal follicular lymphoma. A type of "in-situ" follicular lymphoma presents as intrafollicular neoplastic cells in a background of architecturally normal lymphoid tissue and may be difficult to recognize in routine sections. Accurate recognition of the morphologic variants and clinicopathologic subtypes of follicular lymphoma is important to avoid confusing them with other lymphomas and reactive processes; in addition, some of these subtypes of follicular lymphoma display unusually indolent clinical behavior that warrant their separation from "conventional" follicular lymphoma.

Primary follicular lymphoma of the extrahepatic bile duct mimicking a hilar cholangiocarcinoma: case report and review of the literature

We report a case of a 53-year-old Asian woman who presented with abdominal pain, bloating, dysphagia, and signs of incomplete biliary obstruction, having elevated liver function tests but without increased bilirubin. Imaging studies revealed a mass measuring 6.0 x 8.0 cm at the porta hepatis extending to the right lobe of the liver and obstructing the common hepatic duct, causing mild to moderate intrahepatic biliary dilation and variable occlusion of the right portal vein. At laparotomy, an infiltrative neoplasm was noted at the hilum that involved the common bile duct, right and left hepatic ducts, and the right lobe of the liver. Extended right hepatectomy and resection of the extrahepatic bile duct and right portal vein was performed. Histologic examination revealed a high grade follicular lymphoma (grade 3A) with a predominantly follicular pattern of growth. Portal lymph nodes and a staging bone marrow biopsy showed no evidence of lymphoma. The patient subsequently received chemotherapy. Postoperative follow-up of more than 4 years has been uneventful, without disease recurrence. To the best of our knowledge, this is the third report of a primary extranodal follicular lymphoma of the extrahepatic biliary system.

Low stage follicular lymphoma: biologic and clinical characterization according to nodal or extranodal primary origin

Studies suggest that primary extranodal follicular lymphoma (FL) is not infrequent but it remains poorly characterized with variable histologic, molecular, and clinical outcome findings. We compared 27 extranodal FL to 44 nodal FL using morphologic, immunohistochemical, and molecular genetic techniques and evaluated the clinical outcome of these 2 similarly staged groups. Eight cases of primary cutaneous follicle center lymphoma were also studied. In comparison to nodal FL, a greater number of extranodal FL contained a diffuse growth pattern (P=0.004) and lacked CD10 expression (P=0.014). Fifty-four percent of extranodal and 42% of nodal FL cases showed evidence of t(14;18), with minor breakpoints (icr, 3'BCL2, 5'mcr) more commonly found in extranodal cases (P=0.003). Outcome data showed no significant differences in overall survival (P=0.565) and progression-free survival (P=0.627) among extranodal, nodal, and primary cutaneous follicle center lymphoma cases. Analysis of all cases by t(14;18) status indicate that the translocation-negative group is characterized by a diffuse growth pattern (P=0.043) and lower BCL2 expression (P=0.018). The t(14;18)-positive group showed significantly better overall survival (P=0.019) and disease-specific survival (P=0.006) in comparison with the t(14;18)-negative group. In low stage FL, the status of t(14;18) seems to be more predictive of outcome than origin from an extranodal versus nodal site.

Bcl-xL gene expression correlated with lower apoptotic cell numbers and shorter progression-free survival in PCFCL

The expression of bcl-x(L), an antiapoptotic member of the bcl-2 family, has been correlated with poor prognosis in nodal follicular lymphomas (NFLs). So far, it has not been studied in primary cutaneous follicle center lymphomas (PCFCLs), which, compared with NFLs, express less frequently t(14;18)(q32;q21) and bcl-2. Using real-time PCR we measured bcl-xL and bcl-2 gene expression levels in laser-microdissected lymphoma cells of 20 PCFCL frozen sections. Numbers of apoptotic cells labeled by TUNEL assay were negatively correlated with bcl-xL expression levels (r=-0.840, P<0.005). Bcl-xL expression was significantly higher in biopsies of patients who developed relapse or disease progression later compared with patients who did not (P=0.022), and higher levels of bcl-xL gene expression were significantly correlated with shorter progression-free survival (PFS) (P=0.017). None of these features was correlated with bcl-2 gene expression levels. Our findings indicate that bcl-xL overexpression is inversely correlated with PFS in PCFCL. Moreover, the inverse correlation between bcl-xL expression levels and apoptotic cell numbers suggests that bcl-xL, through its antiapoptotic effect, might contribute to tumor cell survival in PCFCL.

Follicular lymphoma of the thyroid gland

The majority of lymphomas arising in the thyroid gland are mucosa-associated lymphoid tissue lymphomas and diffuse large B-cell lymphomas, which arise from a background of chronic lymphocytic thyroiditis. Follicular lymphoma may also present in the thyroid gland, but its clinicopathologic features at this site are not well characterized, leading to difficulties in diagnosis and clinical management. We have addressed this problem by studying the clinical, morphologic, immunophenotypic, and genetic features of 22 such cases. All cases showed morphology characteristic of follicular lymphoma, however, in many the interfollicular neoplastic infiltrate was particularly prominent and all lymphomas contained readily identifiable and often striking lymphoepithelial lesions, features heretofore considered indicative of mucosa-associated lymphoid tissue lymphoma at this site. Furthermore, 13 of 18 cases for which sufficient evidence was available had clinical and/or histologic evidence of chronic lymphocytic thyroiditis. Analysis of genetic and immunohistochemical features identified 2 distinct groups. In 1 group, similar to typical adult follicular lymphoma, cases carried a t(14;18)/IGH-BCL2 and/or expressed Bcl-2, and were mostly CD10-positive and of World Health Organization (WHO) grade 1 to 2. Follicular lymphomas in the other group lacked IGH-BCL2 and Bcl-2 expression, were often of WHO grade 3 and were often CD10-negative, similar to the minority of follicular lymphomas previously described that are Bcl-2-negative and are often encountered at other extranodal sites. The 2 groups differed in clinical stage at presentation, 11 patients in the former group but none in the latter group having disease beyond the thyroid gland. Appreciation of the spectrum of morphologic, immunophenotypic, and genetic characteristics of follicular lymphoma presenting in the thyroid gland should aid both diagnosis and clinical management.

Lymphomas involving the breast: a study of 106 cases comparing localized and disseminated neoplasms

Lymphomas involving the breast account for approximately 2% of extranodal and <1% of all non-Hodgkin lymphomas. Our aim in this study was to classify breast lymphomas using the World Health Organization classification and then compare this classification with clinical, histologic, and radiologic findings as well as survival. The study group included 106 patients with breast lymphoma (105 women and 1 man). The neoplasms were divided into 2 groups based on extent of disease at initial diagnosis: localized disease (n=50) and disseminated disease (n=56). The follow-up period ranged from 4 to 252 months (median, 49 mo). Almost all (97%) patients presented with a palpable breast mass or masses. In the localized group, diffuse large B-cell lymphoma (DLBCL) was most frequent (n=32, 64%). In the disseminated group, follicular lymphoma was most frequent and exclusive to this group (P=0.0004). Mucosa-associated lymphoid tissue lymphomas occurred in both groups without a significant difference in frequency. A variety of other types of B-cell and T-cell non-Hodgkin lymphomas and classical Hodgkin lymphoma involved the breast at much lower frequency; most of these neoplasms involved the breast as part of disseminated disease. The clinical presentation correlated with radiologic findings: localized lymphomas presented as solitary masses, whereas disseminated lymphomas commonly presented as multifocal masses. There was a significant difference in the disease-free survival between patients with localized and disseminated DLBCL (P=0.003). In the disseminated group, patients with DLBCL had a worse disease-free survival compared with patients with mucosa-associated lymphoid tissue lymphoma or follicular lymphoma (P=0.01).

Practical detection of t(14;18)(IgH/BCL2) in follicular lymphoma

The t(14;18)(q32;q21) translocation is the genetic hallmark of follicular lymphoma. Detection of this translocation can facilitate the diagnosis of follicular lymphoma and can be used to monitor response to therapy and level of residual disease. We herein review and compare practical techniques for detecting t(14;18)(q32;q21), including conventional cytogenetics, fluorescence in situ hybridization, Southern blot analysis, and polymerase chain reaction-based assay. Emphasis is placed on fluorescence in situ hybridization and polymerase chain reaction-based assay, given the applicability of these techniques to fixed, paraffin-embedded tissue.

Application of Immunohistochemistry in the Diagnosis of Non-Hodgkin and Hodgkin Lymphoma

Context.—Beginning with the immunologic classifications of Lukes and Collins and Kiel and culminating in the Revised European-American Lymphoma and World Health Organization classifications, the diagnosis of lymphoid tumors relies heavily on the determination of cell lineage, maturation, and function, based on antigen expression in addition to morphology and clinical features. Technologic advances in immunology, antibody production, genetic analysis, cloning, and the identification of new genes and proteins by microarray and proteomics have provided pathologists with many antibodies to use in routine diagnosis.

Objective.—To provide guidance to the practicing pathologist in the appropriate selection of an antibody panel for the diagnosis of lymphoma based on morphology and relevant clinical data and to avoid pitfalls in the interpretation of immunohistochemical data. Attention is given to some of the newer antibodies, particularly against transcription factors, that are diagnostically and prognostically useful.

Data Sources.—The information presented in this article is based on review of the literature using the OVID database (Ovid MEDLINE 1950 to present with daily update) and 20 years of experience in diagnostic hematopathology.

Conclusions.—Immunophenotyping is required for the diagnosis and classification of lymphoid malignancies. Many paraffin-reactive antibodies are available to the pathologist but most are not specific. To avoid diagnostic pitfalls, interpretation of marker studies must be based on a panel and knowledge of a particular antigen's expression in normal, reactive, and neoplastic conditions.

''Minor'' BCL2 breakpoints in follicular lymphoma: frequency and correlation with grade and disease presentation in 236 cases

Follicular lymphomas are frequently associated with the t(14;18)(q32;q21). This translocation can be detected by karyotype, polymerase chain reaction (PCR), and fluorescence in situ hybridization (FISH). In addition to the breakpoints currently used for diagnosis located in the major breakpoint region (MBR) and the minor cluster region (mcr), recent studies have reported the existence of other breakpoints (3' BCL2, 5'mcr, and icr). In this study, we examined the frequency of all five breakpoints in 236 cases of follicular lymphomas by real-time PCR analysis. The distribution of breakpoint sites consisted of MBR in 118 cases (50%), mcr in 11 (5%), icr in 32 (13%), 3' BCL2 in 13 (6%), and 5' mcr in three cases (1%). These findings illustrate significantly higher frequency of the icr breakpoint as compared with the more frequently studied mcr. Correlation of breakpoints with histology showed that MBR breakpoints occur more frequently in grade 2 lymphomas (P = 0.042). A majority of the PCR-negative cases (75%) contained an IGH/BCL2 translocation with FISH methods, suggesting the presence of other BCL2 breakpoints. Correlation of breakpoints with survival did not reveal significant differences. Diagnostic laboratories should consider expanding their PCR methods to include other BCL2 breakpoints and correlating with FISH methods when appropriate.

Primary Follicular Lymphoma of the Testis and Epididymis in Adults

Primary testicular lymphomas typically occur in patients over 60 years of age. Most are diffuse large B-cell lymphomas with frequent dissemination and a poor prognosis. Primary follicular lymphoma of the adult testis has not been well characterized. However, a small number of primary testicular follicular lymphomas have recently been described in children. These showed stage 1E disease, a lack of BCL2 gene rearrangement and Bcl-2 protein expression, and a good clinical outcome. Here, we describe 5 cases of primary follicular lymphoma of the testis and epididymis in adults. These presented as unilateral testicular masses 12 to 40 mm in diameter and were characterized histologically by small neoplastic follicles in a sclerotic background. The neoplastic cells expressed CD10 and Bcl-6, but not Bcl-2 and lacked t(14;18)(q32;q21)/IGH-BCL2 and BCL6 gene rearrangements. Four of the five patients were 35 years old or younger, and 4 presented with stage 1EA disease. Although follow-up is 12 months or less in 2 of the 5 patients, to date each has followed an indolent clinical course. These features are different from those of most adult nodal follicular lymphomas but are very similar to those of the pediatric primary testicular follicular lymphomas. Together, the pediatric and adult cases represent a discrete clinicopathologic entity of t(14;18)(q32;q21)/IGH-BCL2-negative primary follicular lymphoma of the testis and epididymis, which typically present as clinically indolent localized disease in young males and should be distinguished from the diffuse large B-cell lymphoma more frequently seen in the testes of older adults.