Molecular cytogenetic evidence of t(14;18)(IGH;BCL2) in a substantial proportion of primary cutaneous follicle center lymphomas

In contrast to nodal follicular lymphoma, limited data exist on genetic changes in primary cutaneous follicular lymphoma (primary cutaneous follicle center lymphoma according to WHO-EORTC). The detection rate of the BCL2 rearrangement, representing the characteristic t(14;18)(q32;q21) underlying follicular lymphoma, by polymerase chain reaction (PCR) has been reported to vary over a wide range (0%-41%), and only a few cases have been studied by molecular cytogenetic techniques such as fluorescence in situ hybridization (FISH). In this study, 27 primary cutaneous follicle center lymphomas were analyzed by FISH and the results compared with those obtained by PCR. FISH demonstrated translocations affecting the immunoglobulin heavy chain locus (IGH) in 14 of 27 cases (52%): a t(14;18)(q32;q21) involving BCL2 was found in 11 cases (41%), a t(3;14)(q27;q32) affecting BCL6 in 2 cases (7%), and in 1 case the partner gene of IGH could not be identified. Interestingly, PCR did not detect BCL2 rearrangement in any case. These data suggest that the t(14;18)(q32;q21) frequently occurs in primary cutaneous follicular lymphoma. The reason(s) why BCL2 rearrangements escape the detection by PCR is (are) not clear but could be due to BCL2 mutations, breakpoints outside the amplified DNA, or a high load of somatic mutations.     

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.     

Mantle cell lymphoma involving skin: cutaneous lesions may be the first manifestation of disease and tumors often have blastoid cytologic features

We describe five cases of mantle cell lymphoma involving skin. Three patients initially presented with skin lesions but had evidence of widespread disease at time of diagnosis or with relatively short follow-up. One patient was known to have disseminated disease before he developed skin lesions. One patient presented with a solitary skin nodule on the thigh and has developed multiple smaller nodules on the same leg, but no other sites of disease over 30 months of clinical follow-up. This case fulfills the criteria for primary cutaneous lymphoma as proposed by the European Organization for Research and Treatment of Cancer. Biopsy of the skin lesions in all cases showed predominantly dermal and focally subcutaneous lymphoid infiltrates, preferentially perivascular and periadnexal in four cases, and nodular in one case. The tumors were composed of small- to medium-sized lymphocytes with irregular nuclear contours. Four cases had blastoid and one case had typical cytologic features. Immunophenotypic studies showed that all cases were positive for CD20 and cyclin D1, and four of five were positive for CD5. Four cases, including the CD5-negative case, had evidence of the t(11;14) shown by either fluorescence in situ hybridization methods performed on skin tumors or conventional cytogenetic analysis performed on involved bone marrow. We conclude that mantle cell lymphoma can involve skin, usually as a manifestation of disseminated disease, and is often associated with blastoid cytologic features. Rare cases of mantle cell lymphoma may arise in skin.     

Cyclin D1-negative blastoid mantle cell lymphoma identified by SOX11 expression

SOX11 expression has been recently shown to be useful in the diagnosis of mantle cell lymphoma (MCL), including cyclin D1-negative MCL with typical morphology. We evaluated SOX11 expression pattern in B-cell non-Hodgkin lymphoma (B-NHL) subtypes to confirm specificity and used it as a feature to identify the first reported cases of cyclin D1-negative blastoid MCL. SOX11 expression was evaluated by immunohistochemistry in 140 cases of mature B-NHL, including 4 cases of suspected blastoid MCL that lacked cyclin D1 expression and 8 cases of CD5-positive diffuse large B-cell lymphoma (DLBL). In addition, 5 cases of B or T lymphoblastic lymphoma were included. Nuclear expression of SOX11 was found in cyclin D1-positive MCL (30/30, 100%) and in a case of cyclin D1-negative MCL with typical morphology. SOX11 was also expressed in Burkitt lymphoma (1/5, 20%) and lymphoblastic lymphoma (2/3 T-LBLs, 2/2 B-LBLs, overall 4/5, 80%), whereas all cases of DLBL (including CD5 DLBL) and other small B-NHL were negative. The 4 suspected cases of blastoid MCL were also SOX11. These cases had a complex karyotype that included 12p abnormalities. We confirmed prior reports that stated that SOX11 nuclear expression was a specific marker for MCL, including cyclin D1-negative MCL with typical morphology. To our knowledge, this is the first report regarding its use in identifying cases of cyclin D1-negative blastoid MCL. Routine use of SOX11 in cases of suspected CD5 DLBL might help identify additional cases of cyclin D1-negative blastoid MCL.     

Genetic aberrations in primary cutaneous large B-cell lymphoma: a fluorescence in situ hybridization study of 25 cases

In contrast to nodal large B-cell lymphomas, recurrent chromosomal aberrations have been studied only in a small number of cases of primary cutaneous diffuse large B-cell lymphoma (PCDLBCL). We investigated 25 PCDLBCLs (classified according to the WHO-EORTC classification into PCDLBCL, leg-type, 8; and PCDLBCL, other, 17), using an interphase fluorescence in situ hybridization technique. All cases were analyzed for chromosomal aberrations commonly observed in nodal large B-cell lymphomas, including structural aberrations of the genes BCL2, BCL6, and c-MYC, and numerical aberrations of the chromosomes/genes 3, 7, 8, 11, 12, 13, 17, 18q, RB1, and p53. We observed genetic aberrations in 19 (76%) of 25 patients. The most frequent numerical aberrations were gains of chromosome 12 (7 of 25, 28%), 7 (5 of 25, 20%), 3 (5 of 25, 20%), 18q (3 of 25, 12%), 11 (3 of 25, 12%), X (3 of 25, 12%), and losses of chromosome/gene 17/p53 (3 of 25, 12%). BCL2, c-MYC, and BCL6 were rearranged with the IGH gene in 4 (16%), 1 (4%), and none (0%) of 25 cases, respectively. Most aberrations were homogeneously distributed among cases of PCDLBCL, leg-type and of PCDLBCL, other, cases located on the leg or at other body sites, cases with round and cleaved cell morphology, and Bcl-2+ and Bcl-2- cases. These results suggest that PCDLBCLs show similar chromosomal aberrations irrespective of classification, anatomic site, cell morphology, and Bcl-2 expression, and that many similarities between primary cutaneous and nodal diffuse large B-cell lymphomas can be observed.     

Histologic and immunohistologic findings and prognosis of 40 cases of gastric large B-cell lymphoma

It has been considered that gastric large B cell lymphoma mainly consists of mucosa-associated lymphoid tissue lymphoma (MALToma) with large cell transformation. However, debate continues about the cell lineage. We analyzed 61 operated cases of gastric B cell lymphoma, mainly focusing on 40 cases of diffuse large cell lymphoma (DLCL). Immunohistologically, two cases were classified as CD10-positive follicular lymphoma, 19 cases were low-grade MALToma, 11 CD10-negative DLCL with a component of low-grade MALToma (high-grade MALToma), 12 CD10-positive DLCL, and 17 CD10-negative DLCL without MALToma (pure DLCL). Lymphoepithelial lesion (LEL) was found in all -cases of high-grade MALToma, and in eight of these its invasion was confined to the mucosa and submucosa. Expression of Bcl-6 was detected in two cases of high-grade MALToma. Only two cases of CD10-positive DLCL had large cell LEL, and seven cases showed tumor invasion beyond the submucosa. All 12 cases were positive for Bcl-6, and a delicate meshwork of CD35 (Ber-MAC-DRC)-positive follicular dendritic cells was detected in eight cases. Pure DLCL of all 17 cases reached the proper muscle layer or more, and expression of Bcl-6 was detected in 10 cases. For patients with pure DLCL, overall survival was significantly (p <0.05) worse than those of high-grade MALToma and CD10-positive DLCL by Kaplan-Meier and log-rank methods. Clinical staging and Bcl-6 expression were also good prognostic factors in patients with DLCL. Three groups of gastric DLCL each had unique histologic findings, immunohistologic characteristics, and prognosis.     

Histiocyte-rich B-cell lymphoma. A distinct clinicopathologic entity possibly related to lymphocyte predominant Hodgkin's disease, paragranuloma subtype.

This study reports six non-Hodgkin's lymphoma cases that we called histiocyte-rich B-cell lymphoma (BCL) because of the prominent reactive histiocytic infiltrate obscuring the malignant B-cell population. The involved lymph nodes are characterized by a mixed nodular and diffuse infiltrate and occasionally feature prominent sinuses. The infiltrate is composed of reactive lymphocytes and numerous histiocytes obscuring a tumor population composed of variably sized scattered cells with irregular or multilobar vesicular nuclei. Immunostaining of paraffin sections for the B-cell marker recognized by L26 helps in the identification of these neoplastic cells. The clonal nature and further evidence of the B-cell lineage of this condition is shown by immunoglobulin gene rearrangements detected in three cases. The six cases of histiocyte-rich BCL are remarkably similar clinically: all presented with stage IVB disease with splenomegaly and follow an aggressive clinical course. Except for these features, our series show striking similarities to paragranuloma lymphocyte-predominant Hodgkin's disease, including male preponderance (all patients are male), age distribution (mean age, 41 years), propensity to progress to a diffuse, large B-cell lymphoma (two cases), as well as morphology of the neoplastic B-cell population and expression of Hodgkin's cell markers (Leu-M1 positivity after neuraminidase digestion in three cases, Leu-M1 positivity without neuraminidase digestion in one case, and additional epithelial membrane antigen [EMA] positivity in two cases). Both morphologically and clinically, the present series can be differentiated from other types of infiltrate-rich BCL, such as T-cell-rich BCL. Although additional cases will have to be recognized, histiocyte-rich B-cell lymphoma most likely represents a distinct clinicopathological entity. We speculate that it develops from a subset of B cells that also gives rise to the lymphocytic-histiocytic (L/H) cell, the Hodgkin's cell variant of lymphocyte-predominant Hodgkin's disease, paragranuloma subtype.     

Lymphocytic lymphoma of intermediate differentiation. Morphologic and immunophenotypic spectrum and clinical correlations

All cases of lymphocytic lymphoma of intermediate differentiation (IDL) referred to the National Cancer Institute were reviewed in order to define the histopathologic spectrum of the disease and to investigate morphologic and immunophenotypic features with potential prognostic relevance. Thirty-three cases were classified as IDL according to histologic criteria. Immunophenotypic analysis was performed in 27 cases, and clinical records were available for 22 patients. The median age was 58 years, and the male-to-female ratio, 3.4:1. All patients presented with stage III or IV disease, and five had extranodal presentations. Median survival was 56.3 months, with only three patients having a prolonged relapse-free survival (greater than 2 years). Morphologically, 14 cases were diffuse or only vaguely nodular; 18 cases showed a mantle zone pattern with naked germinal centers. There was a trend toward prolonged median survival for patients with the mantle zone (77.4 months, p = 0.098). The neoplastic population was composed of irregular or cleaved small lymphoid cells with a mitotic rate ranging from 5 to 62 per 20 high-power fields (hpf). A histologically distinctive variant with blastic cytologic features was identified (seven cases). The blastic variant was associated with a higher mitotic index (51.3 versus 19.0) and shortened survival (24.9 months). In contrast to the histologic progression often observed in follicular lymphomas, in no case was transformation to a large-cell or small noncleaved lymphoma observed. All cases had a mature B-cell phenotype demonstrating monoclonal Ig and B-cell surface antigens. Seventy-eight percent were CD5 positive; three of six CD5-negative cases presented in mucosal-associated extranodal sites. CD10 and CD25 were expressed in 52% and 44%, respectively, but did not show clinical correlations. The proliferative rate measured by Ki-67 positivity correlated with the mitotic index, but neither of these parameters had a statistically significant influence on survival.     

Primary bone marrow lymphoma: an uncommon extranodal presentation of aggressive non-hodgkin lymphomas

Bone marrow involvement by lymphoma is considered a systemic dissemination of the disease arising elsewhere, although some tumors may arise primarily in the bone marrow microenvironment. Primary bone marrow lymphoma (PBML) is a rare entity whose real boundaries and clinicobiological significance are not well defined. Criteria to diagnose PBML encompass isolated bone marrow infiltration, with no evidence of nodal or extranodal involvement, including the bone, and the exclusion of leukemia/lymphomas that are considered to primarily involve the bone marrow. Twenty-one out of 40 lymphomas retrospectively reviewed by the International Extranodal Lymphoma Study Group from 12 institutions in 7 different countries over a 25-year period fulfilled the inclusion criteria. These cases comprised 4 follicular lymphomas (FLs), 15 diffuse large B-cell lymphomas (DLBCLs), and 2 peripheral T-cell lymphomas, not otherwise specified. The FL cases showed paratrabecular infiltration, BCL2 protein and CD10 expression, and BCL2 gene rearrangement. DLBCL showed nodular infiltration in 6 cases and was diffuse in 9 cases; it also showed positivity for BCL2 protein (9/10) and IRF4 (6/8). Median age was 65 years with male predominance. All but 3 FL patients were symptomatic. Most cases presented with cytopenias and high lactate dehydrogenase. Four patients (3 FL cases and 1 DLBCL case) had leukemic involvement. Most DLBCL patients received CHOP-like or R-CHOP-like regimens. The outcome was unfavorable, with a median overall survival of 1.8 years. In conclusion, PBML is a very uncommon lymphoma with particular clinical features and heterogenous histology. Its recognition is important to establish accurate diagnosis and adequate therapy.     

Progression to large B-cell lymphoma in splenic marginal zone lymphoma: a description of a series of 12 cases.

Splenic marginal zone lymphoma (SMZL) is considered to be an indolent extranodal B-cell lymphoma. Despite its low aggressivity, histologic progression has been described in sporadic reports, although the frequency, characteristics, and underlying molecular abnormalities of this phenomenon are largely unknown. We review here the clinical, morphologic, immunohistochemical, and molecular features of a series of 12 SMZL cases that showed progression to large B-cell lymphoma (LBCL). The most frequent location of secondary LBCL was in peripheral lymph node. This occurred between 12 and 85 months after diagnosis of SMZL. However, in two cases LBCL was diagnosed at the initial stage of the disease (one spleen tumoral nodule and one hilar lymph node). The histologic and immunophenotypic features of these cases were similar to those of transformed LBCL at other sites. In four cases the immunoglobulin heavy chain gene polymerase chain study revealed the same rearrangement pattern in both primary and secondary tumors, thereby confirming their identity and excluding the possibility of a second malignancy. As is the case with other low-grade lymphoproliferative disorders, SMZL may undergo high-grade transformation. These 12 cases represent 13% of our series of SMZL with adequate follow-up. The incidence of large cell transformation in SMZL seems to be lower than in follicular lymphoma (25-60%) and mantle cell lymphoma (11-39%), although it is similar to the frequency of transformation in B-chronic lymphocytic lymphoma/small lymphocytic lymphoma (1-10%). The mean proliferative index (MIB1 staining) in initial SMZL specimens of cases with LBCL transformation was 28.6%, higher than that of MIB1 staining in the overall SMZL series (21.8%), although not statistically significantly so. p53 or p16INK4a inactivation in this series was observed in only one case, in contrast with the situation observed in chronic lymphocytic leukemia, follicular lymphoma, and mantle cell lymphoma. It seems that progression in SMZL is mainly independent of p53 or p16INK4a inactivation. The frequency of the 7q deletion in this series was 3 of 7 (42%). 7q loss may play an alternative role in the inactivation of the p53 and p16INK4a pathway, thereby favoring tumoral progression.     

Neoplastic cells do not carry bcl2-JH rearrangements detected in a subset of primary cutaneous follicle center B-cell lymphomas

Whether primary cutaneous follicular lymphoma (PCFL) may or not represent a cutaneous equivalent to nodal follicular lymphoma (FL) is not determined. We have therefore investigated a series of PCFL to determine if tumoral cells carry or not the t(14;18)(q32;q21) translocation, a cytogenetic hallmark of nodal FL. Thirty cases of PFCL were selected according to the criteria of both the European Organisation for Research and Treatment of Cancer and the World Health Organization with 21 cases classified as grade 1 or 2 and 9 cases as grade 3. First, cutaneous tumors were studied by PCR for the amplification of bcl-2/JH rearrangements and by interphase fluorescence in situ hybridization using a dual color probe spanning t(14;18) breakpoints. Second, we tried to determine the origin of bcl2-JH-positive cells by a parallel bcl2-JH and immunoglobulin heavy chain gene amplification of blood mononuclear cells DNA and of DNA extracted from single microdissected B cells. Bcl2-JH rearrangements were amplified by PCR in skin of 9 of 30 (30%) patients with a similar-sized bcl2-JH rearrangement detected in the blood of 7 of these 9 cases. No t(14;18) breakpoint was detected by interphase fluorescence in situ hybridization analysis of 11 bcl2-JH-negative and 5 bcl2-JH-positive PCFL in contrast with its detection in the secondary cutaneous FL and in the nodal FL cases. Single-cell/multigene analysis showed that no single monoclonal B cells of PCFL carried the bcl2-JH rearrangement. Bystander or nontumoral t(14;18)+ B cells emigrating from blood may account for the detection of bcl2-JH rearrangements within PCFL material. Our study also underlines the diagnostic value of interphase fluorescence in situ hybridization to discriminate between t(14;18)-negative PCFL and extracutaneous FL involving the skin.     

Splenic marginal-zone lymphoma: one or more entities? A histologic, immunohistochemical, and molecular study of 42 cases

We analyzed 42 splenic marginal-zone lymphoma (SMZL) cases diagnosed on splenectomy specimens after established World Health Organization criteria. A predominantly nodular growth pattern was observed in 24 cases; the remainder showed predominantly (11/42) or exclusively (7/42) diffuse infiltration. Twenty-one cases showed the "classic" biphasic appearance; 13 cases exhibited marginal-zone morphology; finally, 8 cases were composed predominantly of small cells. CD21 and CD35 were expressed by 12/42 and 17/38 cases, respectively. DBA.44 was detected in 24/42 cases. Seventeen of 37 cases were surface IgD (SIgD)-positive. Twenty-one of 22 analyzed cases were SIgM-positive (12/21 coexpressed SIgD). Five of 37 cases were SIgG-positive. CD27 staining was observed in 21/35 cases; 7/18 CD27-positive cases coexpressed SIgD; 7/14 CD27-negative cases were SIgD-positive. Forty IGHV-D-J rearrangements were amplified in 34/42 cases: the IGHV4-34 gene predominated, followed by IGHV1-2. Using the 98% homology cut-off, 25/40 (62.5%) IGHV sequences were considered as "mutated": 10/11 cases with monomorphous, marginal-zone morphology were IGHV-mutated; in contrast, 4/6 cases with monomorphous, small-cell morphology were IGHV-unmutated. Five of 7 cases expressing IGHV1 subgroup genes had biphasic morphology, whereas 6/9 IGHV3-expressing cases had monomorphous, marginal-zone morphology. Most IGHV-mutated cases (14/20; 70%) were SIgD-negative; in contrast, 8/11 IGHV-unmutated cases expressed SIgD. CD27 was detected in 10/17 IGHV-mutated and 6/10 IGHV-unmutated cases. Seven of 11 CD27-negative cases were IGHV-mutated; 5/7 CD27-negative/IGHV-mutated cases expressed DBA.44. These results confirm the considerable histologic, immunohistochemical, and molecular heterogeneity of SMZL and indicate an origin from the diverse resident B-cell populations of the normal SMZ.     

Fluorescence immunophenotypic and interphase cytogenetic characterization of nodal lymphoplasmacytic lymphoma

Lymphoplasmacytic lymphoma (LPL) is a small B-cell lymphoma with plasmacytic differentiation that does not fulfill the criteria for any other small B-cell lymphoma. Cytogenetic characterization of nodal LPL is limited and the distinction from marginal zone lymphomas with plasmacytic differentiation can be problematic. Thus, 17 cases of lymph node-based LPL were studied with fluorescence immunophenotypic and interphase cytogenetics for the investigation of neoplasia (FICTION) using a CD79a antibody and probes to detect trisomies of chromosomes 3 (15 cases), 12 (16 cases), and 18 (17 cases); rearrangements (R) of IgH (10 cases), BCL6 (6 cases), PAX5 (7 cases), and MALT1 (16 cases); and deletion 6q21 (7 cases). Cases with IgH R were further studied with an IgH/BCL2 probe. In cases without FICTION studies, previously reported fluorescence in situ hybridization results for IgH, PAX5, and deletion 6q21 were available from prior studies. The histopathology, immunophenotype, and available clinical data were also reviewed. Three pathologic categories were recognized: 5 classic LPL, 5 vaguely nodular polymorphous (VN-P), and 7 other. Among the classic LPL, 4/4 had an IgM paraproteinemia, 5/5 had bone marrow involvement (BM+), and 1/5 had +MALT1. One of one VN-P LPL had an IgM paraprotein, 2/4 were IgM+, 2/4 IgG+, 1/3 had BM+, and 1/5 had an IgH R. Among the other cases, 2/3 had a paraprotein, 2/7 were IgM+, 5/7 IgG+, and 0/3 had BM+. Of these cases, 1 showed +12, 1 +18, and 1 IgH/BCL2 rearrangement plus +18. None of the 17 cases had a 6q21 deletion or +3. Therefore, with rare exception, lymph node-based LPL with classic or more varied histopathologic features does not have the cytogenetic abnormalities frequently associated with bone marrow-based LPL/Waldenstrom macroglobulinemia or many of the marginal zone lymphomas. The search for better objective inclusionary criteria for LPL must continue.     

胃癌组织中miR-497表达及其生物学意义

目的检测胃癌组织和癌旁组织中miR-497的表达差异,寻找其下游作用靶点。方法选取2010-2013年期间在中国医科大学附属第一医院胃肠外科手术切除的94例胃癌及其癌旁组织。用RT-PCR法定量检测miR-497在其中的表达;在线软件预测miR-497靶基因,用阴性对照及miR-497-mimics转染SGC-7901细胞系,RT-PCR及Western检测胃癌细胞miR-497过表达后靶点基因mRNA及蛋白水平的改变;MTT法检测miR-497-mimics组（miR-497过表达）细胞株与阴性对照组间对5-氟尿嘧啶（5-FU）化疗的敏感性。结果①miR-497表达量在胃癌组织中明显低于癌旁组织,差异有统计学意义（P〈0．01）。②BCL2L2被预测为miR-497的靶基因,miR-497在胃癌SGC-7901细胞中过表达后BCL2L2蛋白表达在miR-497-mimics组细胞中明显弱于阴性对照组细胞,BCL2L2mRNA在2组细胞中的表达差异无统计学意义（P〉0．05）。miR-497-mimics组细胞对5-FU的Ic50值明显低于阴性对照组细胞（P=0．0046）。结论miR-497在胃癌组织中低表达,BCL2L2为miR-497的靶基因,miR-497过表达可提高胃癌细胞对5-Fu的敏感性,这为进一步研究miR-497与BCL2L2在胃癌中的作用及治疗提供了新的方向。     

Composite Hodgkin lymphoma and mantle cell lymphoma: two clonally unrelated tumors

Association of Hodgkin lymphoma and non-Hodgkin lymphoma is rare and, specifically, the combination of Hodgkin lymphoma and mantle cell lymphoma has not been previously described. Here we describe composite mantle cell lymphoma and Hodgkin lymphoma affecting the spleen in one case and the eyelid and cervical lymph nodes in a second. In both, nodules of classical Hodgkin lymphoma were intermixed with diffuse or nodular areas of typical mantle cell lymphoma. Immunohistochemical and molecular analyses confirmed cyclin D1 overexpression secondary to the translocation t(11;14) in the small mantle cell lymphoma component; with CD30, CD15, and EBV expression in the Hodgkin and Reed-Sternberg cells. Finally, clonal analysis of rearranged immunoglobulin genes performed on microdissected Hodgkin and Reed-Sternberg and mantle cell lymphoma cells provided definite evidence of separate clonal origins of the two tumors in the patients. These EBV-positive, clonally unrelated tumors seem to represent true composite neoplasms, in contrast to cases showing merely clonal progression.     

Clinical, immunophenotypic, and genetic analysis of adult lymphomas with morphologic features of Burkitt lymphoma

A prompt distinction of Burkitt lymphoma (BL) versus diffuse large B cell lymphomas (DLBCL) has important clinical implications; however, this distinction can be difficult. We analyzed 74 adult gray zone and 10 reference pediatric BL using immunohistochemistry (Ki-67, CD10, bcl2, bcl6) and fluorescence in situ hybridization (FISH) for MYC, BCL2, and BCL6 breakpoints. Two algorithms for classification were followed: algorithm A used a two-step review by four hemato-pathologists and algorithm B a set of only biologic markers (Ki-67 > or = 90%, CD10+, bcl6+, bcl2-, MYC breakpoint+, BCL2 and BCL6 breakpoint-). Both algorithms categorized all reference cases as BL. In the adult group, algorithm A resulted in 21 adult BL and 52 DLBCL and algorithm B in 23 BL and 51 "non-Burkitt" lymphomas (nBL); 9 cases (12%) contained two different translocations and were categorized as nBL in algorithm B. Fifteen cases (20%) fulfilled the BL criteria of both algorithms. Although not considered as BL according to both algorithms, many other lymphomas showed nonetheless a phenotypic and/or genetic shift to BL. BL according to algorithm B was more homogeneous with respect to clinical presentation (gender and localization) than BL defined by algorithm A. Our data suggest that only a few cases of these gray zone lymphomas represent true de novo BL. Immunohistochemistry for Ki-67, CD10, and bcl2 with analysis of MYC and preferably also BCL2 and BCL6 may be advised as a marker panel for this diagnostic dilemma.     

CD10 and BCL-6 expression in paraffin sections of normal lymphoid tissue and B-cell lymphomas

In this study the authors explored the value of immunostaining for follicular center B-cell markers, BCL-6 and CD10, in paraffin sections as a tool for the differential diagnosis of B-cell lymphomas. The cases studied comprised reactive lymphoid hyperplasia (RLH; n = 19), follicular lymphoma (FL; n = 50), low-grade mucosa-associated lymphoid tissue (MALT) lymphoma (n = 24), mantle cell lymphoma (n = 19), splenic marginal zone lymphoma (n = 13), diffuse large B-cell lymphoma (DLBCL; n = 54), Burkitt's lymphoma (BL; n = 20), nodular lymphocyte predominance Hodgkin's disease (NLPHD; n = 16), and classic Hodgkin's disease (CHD; n = 13). In RLH, CD10 and BCL-6 were expressed almost exclusively by the follicular center cells. In contrast in FL, the expression of CD10 (39/50) and BCL-6 (34/36) was seen in both follicular and interfollicular neoplastic B cells. Marginal zone/MALT lymphomas and mantle cell lymphoma were always negative. In DLBCL the expression was variable for both CD10 (21/54) and BCL-6 (39/47), with some tumors, including cases of transformed follicular lymphoma (9/10), coexpressing CD10 and BCL-6, and others expressing only BCL-6, and a small group expressing neither marker, possibly reflecting the underlying primary pathogenetic events such as the rearrangement of BCL-2 or BCL-6 genes. BL was always both CD10 and BCL-6 positive. In NLPHD the L&H cells expressed BCL-6 (11/13) but not CD10, whereas in CHD BCL-6 expression was seen in half of the cases. This study demonstrates that both CD10 and BCL-6 are reliable markers of follicular center B-cell differentiation. CD10 and BCL-6 immunostaining have an important role in differential diagnosis of FL from RLH and other low-grade B-cell lymphomas. The results also suggest that a CD10/BCL-6 expression pattern may be helpful in identifying main subsets of DLBCL. However, additional studies comparing genotype with immunophenotype are required.