Comparative study of keratinocyte primary culture methods from paediatric skin biopsies for RNA-sequencing.

BACKGROUND: Keratinocyte culture is a standard method used to study gene expression, cell differentiation and proliferation. Numerous protocols exist, however their application is frequently unsuitable for small specimens, such as 4-mm punch skin biopsies. AIMS: This study compared 3 different methods of keratinocyte culture from paediatric skin biopsies to evaluate which one ensures adequate cell growth for RNA extraction and sequencing. MATERIALS AND METHODS: Thirty-six skin samples were obtained from 4-mm punch skin biopsies from residual human body material from healthy children. They were cultured in vitro according to 3 different methods: enzymatic method, epidermis explant and direct explant method. Keratinocytes were characterized by immunocytochemistry using pan-cytokeratin. RNA extraction was performed with RNeasy Mini kit. Quantity and quality of the extracted RNA was assessed to meet the requirements of library preparation for sequencing. RESULTS: The direct explant method had largely shown its superiority over the two other methods, with a 100% success rate and an average of 15 days of culture. RNA extraction yielded a mean of 8545.85 ng of RNA per sample with an RQN of 10. Cover-clip immunochemistry staining with pan-cytokeratin had confirmed the absence of fibroblast contamination. DISCUSSION: Although the enzymatic method is the most frequently used for keratinocyte culture, it is not suitable small samples required in dermatology. The direct explant method guarantees a high growth rate and the extraction of high quality RNA. Variation in the amount of RNA harvested are related to inter- and intra-individual variations and to the conditions of the experiment. CONCLUSION: This study allowed to conclude that the direct explant method is the most efficient and easy method to ensure cell growth when the samples are from 4-mm punch skin biopsies. This technique avoids fibroblasts contamination and obtains a sufficient quantity and quality of RNA to sequence it.

Superficial papular neuroma: Case series of a new entity.

BACKGROUND: Dermal neural lesions arise in various circumstances and may be difficult to classify. METHODS: We describe the clinical, histopathologic and immunophenotypic features of a series of terminally differentiated neural lesions not described previously, to our knowledge. RESULTS: Four cases from men aged 58 to 66 years were included. Some lesions reportedly bled, but no inciting trauma or prior biopsies were reported. None recurred after biopsy, with follow-up ranging from 19 to 113 months. All lesions were papular, with vertically oriented S100-positive spindled cells and nerve fibers in the papillary dermis. Slight epidermal hyperplasia, dilated superficial thin-walled vessels and minimal to mild inflammation were seen in each. Fibers were uniformly fine in 3 cases, with slightly thicker central fibers in the fourth. Three had parakeratotic scale. None were associated with dermal fibrosis or adnexal proliferation. Neurofilament stained axons in each. EMA was negative in all cases. CD34, melan-A and HMB45 were negative when performed. CONCLUSIONS: We report a small series of benign neural lesions and propose the name "superficial papular neuroma" for this distinct entity. Awareness is important to understand the clinical significance of these lesions and avoid misinterpretation that could lead to overtreatment, unnecessary work-up and increased cost.

Evidence of human papillomavirus in the placenta.

Human papillomavirus (HPV) is an epitheliotropic virus typically infecting keratinocytes but also possibly epithelial trophoblastic placental cells. In the present study, we set out to investigate whether HPV can be recovered from transabdominally obtained placental cells to avoid any confounding contamination by HPV-infected cervical cells. Thirty-five placental samples from women undergoing transabdominal chorionic villous sampling were analyzed, and we detected HPV-16 and HPV-62 in 2 placentas. This study suggests that HPV infection of the placenta can occur early in pregnancy. The overall clinical implication of these results remains to be elucidated.

Prognostic significance of VEGF, VEGF receptors, and microvessel density in diffuse large B cell lymphoma treated with anthracycline-based chemotherapy.

Vascular endothelial growth factor-mediated signaling has at least two potential roles in diffuse large B cell lymphoma: potentiation of angiogenesis, and potentiation of lymphoma cell proliferation and/or survival induced by autocrine vascular endothelial growth factor receptor-mediated signaling. We have recently shown that diffuse large B cell lymphomas expressing high levels of vascular endothelial growth factor protein also express high levels of vascular endothelial growth factor receptor-1 and vascular endothelial growth factor receptor-2. We have now assessed a larger multi-institutional cohort of patients with de novo diffuse large B cell lymphoma treated with anthracycline-based therapy to address whether tumor vascularity, or expression of vascular endothelial growth factor protein and its receptors, contribute to patient outcomes. Our results show that increased tumor vascularity is associated with poor overall survival (P=0.047), and is independent of the international prognostic index. High expression of vascular endothelial growth factor receptor-1 by lymphoma cells by contrast is associated with improved overall survival (P=0.044). The combination of high vascular endothelial growth factor and vascular endothelial growth factor receptor-1 protein expression by lymphoma cells identifies a subgroup of patients with improved overall (P=0.003) and progression-free (P=0.026) survival; these findings are also independent of the international prognostic index. The prognostic significance of overexpression of this ligand-receptor pair suggests that autocrine signaling via vascular endothelial growth factor receptor-1 may represent a survival or proliferation pathway in diffuse large B cell lymphoma. Dependence on autocrine vascular endothelial growth factor receptor-1-mediated signaling may render a subset of diffuse large B-cell lymphomas susceptible to anthracycline-based therapy.

Validation of tissue microarray immunohistochemistry staining and interpretation in diffuse large B-cell lymphoma.

Tissue microarrays (TMAs) show concordance with whole tissue sections in the immunohistochemical evaluation of tumor cells. However, potential inter-institutional variability among observers and immunohistochemical staining methods has not been fully addressed. We selected 21 cases of diffuse large B-cell lymphoma (DLBCL) to process for TMAs. Immunohistochemical stains were performed in 3 laboratories, and reviewed independently by 3 hematopathologists at the 3 institutions. Stains were scored on a 4-point scale. Statistical analyses of variation in the scoring among observers and among different institutions' stains were performed. Stains for CD3, CD10, CD20, BCL-2, BCL-6, MIB-1, and FOX-P1 revealed little variation among observers, with an average 51-82% complete agreement and 82-100% agreement +/- 1 numerical score. The rate of concordance when evaluating most stains performed in different laboratories was also relatively good, with an average of 55-72% complete agreement and 70-97% agreement +/- 1 score. However, scoring of MUM-1 and p53 stains showed wider variation, with an average of only 37 and 30% complete agreement among observers, and 11 and 45% agreement when stains from different institutions were examined. Further statistical analyses were performed to compare the observers' scoring of their own institution's stains (self-review) vs. observers' scoring of other institutions' stains (non-self). The agreement rate for the p53 stain was significantly higher when based on self-review (average 58% complete agreement) compared with an agreement rate of only 10.5% when based on a review of stains performed in another laboratory, non-self review, P < 0.01. This difference in the self- vs. non-self review was not seen when data for MUM-1 were analysed. In conclusion, most phenotypic markers used in the analysis of DLBCL can be evaluated in TMAs with adequate agreement among observers and laboratories. These include CD3, CD20, CD10, BCL-2, BCL-6, MIB-1, and FOX-P1. However, some markers, such as p53 and MUM-1, are more prone to inter-institutional variation. Variations in interpretation can be partially overcome by self-adjusted/adapt tendency, as seen with p53. Especially with newly developed markers, such as MUM-1, the development of standardized techniques for staining and interpretation is critical to reduce inter-observer variability.

Giant platelets in a case of deletion 11q24-qter confirmed by fluorescence in situ hybridization.

Here we report the association of giant platelets and an increase in platelet volume in a 19-month-old black female with de novo del 11q24-qter. The deletion, which was visible on karyotype, was further confirmed and more precisely localized by fluorescence in situ hybridization studies (FISH) that showed the deletion to lie distal to the MLL gene region (11q23). Clinically, the case presented less severe symptoms than Jacobsen syndrome-the well known partial deletion of the distal end of chromosome 11. Platelet glycoproteins CD 41, CD 42a, C 42b, CD 61, and PAC-1 were also assayed and found to be normally expressed. To our knowledge, giant platelets are described for the first time in the relevant deleted region.

Usefulness of anti-CD117 in the flow cytometric analysis of acute leukemia.

We assessed the diagnostic usefulness of adding anti-CD117 to our existing flow cytometric profile in the analysis of 150 consecutive cases of acute leukemia (de novo or relapsed acute myelogenous leukemia [AML], AML arising in myelodysplastic syndrome, blast crisis of chronic myelogenous leukemia [CML], acute lymphoblastic leukemia, acute unclassifiable leukemia, and biphenotypic leukemia). CD117 was expressed on more than 10% of blasts in 64% of de novo AMLs (42/66), 95% of relapsed AMLs (19/20), 75% of AMLs arising from a myelodysplastic syndrome (6/8), and 25% of myeloid blast crisis in CMLs (1/4). CD117 was not expressed in acute lymphoblastic, acute biphenotypic, or unclassified leukemia or lymphoid blast crisis of CML. The specificity, positive predictive value, sensitivity, and negative predictive value of CD117 for AML were 100%, 100%, 69%, and 62%, respectively. CD117 is a specific marker for myeloblastic leukemias. Sensitivity is greatest in French-American-British M2 and relapsed AML. Intensity of CD117 expression is dim. Despite the high specificity and positive predictive value, the addition of anti-CD117 to our panel did not prove essential for the assignment of blast lineage.

A new immunostain algorithm classifies diffuse large B-cell lymphoma into molecular subtypes with high accuracy.

PURPOSE: Hans and coworkers previously developed an immunohistochemical algorithm with approximately 80% concordance with the gene expression profiling (GEP) classification of diffuse large B-cell lymphoma (DLBCL) into the germinal center B-cell-like (GCB) and activated B-cell-like (ABC) subtypes. Since then, new antibodies specific to germinal center B-cells have been developed, which might improve the performance of an immunostain algorithm. EXPERIMENTAL DESIGN: We studied 84 cases of cyclophosphamide-doxorubicin-vincristine-prednisone (CHOP)-treated DLBCL (47 GCB, 37 ABC) with GCET1, CD10, BCL6, MUM1, FOXP1, BCL2, MTA3, and cyclin D2 immunostains, and compared different combinations of the immunostaining results with the GEP classification. A perturbation analysis was also applied to eliminate the possible effects of interobserver or intraobserver variations. A separate set of 63 DLBCL cases treated with rituximab plus CHOP (37 GCB, 26 ABC) was used to validate the new algorithm. RESULTS: A new algorithm using GCET1, CD10, BCL6, MUM1, and FOXP1 was derived that closely approximated the GEP classification with 93% concordance. Perturbation analysis indicated that the algorithm was robust within the range of observer variance. The new algorithm predicted 3-year overall survival of the validation set [GCB (87%) versus ABC (44%); P < 0.001], simulating the predictive power of the GEP classification. For a group of seven primary mediastinal large B-cell lymphoma, the new algorithm is a better prognostic classifier (all "GCB") than the Hans' algorithm (two GCB, five non-GCB). CONCLUSION: Our new algorithm is significantly more accurate than the Hans' algorithm and will facilitate risk stratification of DLBCL patients and future DLBCL research using archival materials.

Cutaneous malakoplakia.

Malakoplakia is an acquired granulomatous disorder first described by Michaelis and Gutmann in 1902. The pathogenesis of malakoplakia is poorly understood, but it is thought to be secondary to an acquired bacteriocidal defect in macrophages occurring mostly in immunosuppressed patients or in the setting of autoimmune disease. Malakoplakia has been described in numerous anatomic locations, most commonly in the genitourinary tract. Microscopically, malakoplakia consists predominantly of sheets of macrophages known as von Hansemann cells with scattered targetoid intracytoplasmic inclusions known as Michaelis-Gutmann bodies. Cutaneous malakoplakia is a rare entity with less than 50 cases reported in the literature. In this article, we review cutaneous malakoplakia including the clinical, gross, and microscopic features as well as the treatment and prognosis of 40 cases of cutaneous malakoplakia identified in the literature.

Addition of rituximab to standard chemotherapy improves the survival of both the germinal center B-cell-like and non-germinal center B-cell-like subtypes of diffuse large B-cell lymphoma.

PURPOSE: Diffuse large B-cell lymphoma (DLBCL) includes at least two prognostically important subtypes (ie, germinal center B-cell-like [GCB] and activated B-cell-like [ABC] DLBCL), which initially were characterized by gene expression profiling and subsequently were confirmed by immunostaining. However, with the addition of rituximab to standard chemotherapy, the prognostic significance of this subclassification of DLBCL is unclear. PATIENTS AND METHODS: We studied 243 patient cases of de novo DLBCL, which included 131 patient cases treated with rituximab plus standard chemotherapy (rituximab group) and 112 patient cases treated with only standard chemotherapy (control group). The cases were assigned to GCB or non-GCB subgroups (the latter of which included both ABC DLBCL and unclassifiable DLBCL) on the basis of immunophenotype by using the Hans method. Clinical characteristics and survival outcomes of the two patient groups were compared. RESULTS: The clinical characteristics of the patients in the rituximab and the control groups were similar. Compared with the control group, addition of rituximab improved the 3-year overall survival (OS; 42% v 77%; P < .001) of patients with DLBCL. Rituximab-treated patients in either the GCB or the non-GCB subgroups also had a significantly improved 3-year OS compared with their respective subgroups in the control group (P < .001). In the rituximab group, the GCB subgroup had a significantly better 3-year OS than the non-GCB subgroup (85% v 69%; P = .032). Multivariate analyses confirmed that rituximab treatment was predictive for survival in both the GCB and the non-GCB subgroups. CONCLUSION: In this retrospective study, we have shown that the subclassification of DLBCL on the basis of the cell of origin continues to have prognostic importance in the rituximab era.

LMO2 protein expression predicts survival in patients with diffuse large B-cell lymphoma treated with anthracycline-based chemotherapy with and without rituximab.

PURPOSE: The heterogeneity of diffuse large B-cell lymphoma (DLBCL) has prompted the search for new markers that can accurately separate prognostic risk groups. We previously showed in a multivariate model that LMO2 mRNA was a strong predictor of superior outcome in DLBCL patients. Here, we tested the prognostic impact of LMO2 protein expression in DLBCL patients treated with anthracycline-based chemotherapy with or without rituximab. PATIENTS AND METHODS: DLBCL patients treated with anthracycline-based chemotherapy alone (263 patients) or with the addition of rituximab (80 patients) were studied using immunohistochemistry for LMO2 on tissue microarrays of original biopsies. Staining results were correlated with outcome. RESULTS: In anthracycline-treated patients, LMO2 protein expression was significantly correlated with improved overall survival (OS) and progression-free survival (PFS) in univariate analyses (OS, P = .018; PFS, P = .010) and was a significant predictor independent of the clinical International Prognostic Index (IPI) in multivariate analysis. Similarly, in patients treated with the combination of anthracycline-containing regimens and rituximab, LMO2 protein expression was also significantly correlated with improved OS and PFS (OS, P = .005; PFS, P = .009) and was a significant predictor independent of the IPI in multivariate analysis. CONCLUSION: We conclude that LMO2 protein expression is a prognostic marker in DLBCL patients treated with anthracycline-based regimens alone or in combination with rituximab. After further validation, immunohistologic analysis of LMO2 protein expression may become a practical assay for newly diagnosed DLBCL patients to optimize their clinical management.

Aneuploidy study in sperm and preimplantation embryos from nonmosaic 47,XYY men.

OBJECTIVE: To determine gonosomal and autosomal aneuploidy rate in sperm and preimplantation embryos from nonmosaic 47,XYY males. DESIGN: Sperm and blastomere analysis by fluorescence in situ hybridization. SETTING: Fertility clinic, academic hospital. PATIENT(S): Two 47,XYY men undergoing preimplantation genetic diagnosis (PGD) and eight 46,XY males distributed in two control groups (fertile and infertile). INTERVENTION(S): Sperm-sample collection for fluorescence in situ hybridization and PGD. MAIN OUTCOME MEASURE(S): Aneuploidy frequencies for chromosomes X, Y, 13, 16, 18, 21, and 22 in sperm and embryos. RESULT(S): Patients with 47,XYY presented global sperm gonosomal and autosomal aneuploidy frequency of 37.23%-37.80%, with XY disomy being the most frequent abnormality (16.70%-19.01%). This aneuploidy rate was statistically significantly different from that found in both 46,XY infertile controls (1.07%) and 46,XY fertile controls (1.04%). In total, 47 preimplantation embryos were analyzed, of which 32 were classified as normal (68%) and 15 as aneuploid (32%). Among the abnormal embryos, 9 presented gonosomal abnormalities, and 6, autosomal abnormalities. CONCLUSION(S): High rate of gonosomal and autosomal aneuploidy was observed in sperm and preimplantation embryos from nonmosaic 47,XYY males. The offspring of this category of patients may be at higher risk of chromosomal abnormalities, and therefore PGD can be suggested to these patients.

Langerhans cell histiocytosis associated with myelodysplastic syndrome in adults.

BACKGROUND: Myelodysplastic syndrome (MDS) is a group of bone marrow disorders associated with dyplasia of myeloid elements that may have cutaneous manifestations including infections, vasculitis, Sweet's syndrome, pyoderma gangrenosum, erythema elevatum diutinum, and leukemia cutis. These cutaneous manifestations are attributed to the underlying bone marrow defect. Langerhans cell histiocytosis (LCH) is primarily a pediatric disease, and rarely LCH has been described in association with pediatric MDS. We are aware of only a single case report of LCH associated with MDS in an adult. METHODS: We report two new cases of LCH in elderly patients with underlying MDS. The specimens were examined by routine microscopy as well as immunohistochemical stains for S100 protein and CD1a. RESULTS: Both patients were elderly men with established diagnoses of MDS. One presented with a solitary pruritic papule while the other had a 2-year history of erythematous papules involving the trunk and extremities. Histologic examination revealed intraepidermal and dermal collections of mononuclear cells with reniform nuclei. The cells were strongly positive for S100 and CD1a, confirming their identity as Langerhans cells. CONCLUSION: Cutaneous LCH may be associated with underlying MDS in adults and should be considered in the differential diagnosis of cutaneous eruptions in patients with MDS.

BCL2 expression is a prognostic marker for the activated B-cell-like type of diffuse large B-cell lymphoma.

BACKGROUND: The role of BCL2 as a predictor of survival in diffuse large B-cell lymphoma (DLBCL) is controversial. DLBCL is heterogeneous, and the expression of BCL2 is variable within the two major subgroups of DLBCL, germinal center B-cell-like (GCB) and activated B-cell-like (ABC) DLBCL, as well as primary mediastinal DLBCL. PATIENTS AND METHODS: In this study, we investigated the correlation of BCL2 expression with survival in the two major subgroups of DLBCL, as well as the mechanisms of BCL2 expression. RESULTS: There was no significant correlation between BCL2 protein expression and overall survival within the GCB subgroup, but BCL2 expression had a significant adverse effect on overall survival within the ABC subgroup (P = .008). This correlation was also observed at the mRNA level (P < .04). The difference remained significant when the analyses were performed at different cutoff values. The t(14;18) was frequently observed in the GCB subgroup and was highly associated with BCL2 expression. Patients with ABC DLBCL did not exhibit t(14;18) but had a markedly higher frequency of chromosome 18q21 amplification, on which BCL2 resides. Thus, alternative mechanisms such as 18q21 amplification or activation of the nuclear factor-kappa B pathway, as reported previously, seem to be mainly responsible for the upregulation of BCL2 expression in the ABC subgroup. CONCLUSION: Treating all DLBCL as a single entity ignores the mechanistic differences in BCL2 upregulation and obscures the prognostic significance of BCL2 expression. Hence, the significance of BCL2 and other biomarkers should be assessed in the context of DLBCL subgroups in future studies.

Expression of PKC-beta or cyclin D2 predicts for inferior survival in diffuse large B-cell lymphoma.

We sought to determine whether identification of poor-risk subgroups of diffuse large B-cell lymphoma (DLBCL) using immunohistochemical stains would have practical utility with regard to prognosis and therapeutic decisions. Tissue microarray blocks were created using replicate samples of formalin-fixed, paraffin-embedded tissue from 200 cases of de novo DLBCL. The sections were stained with antibodies to proteins that are expressed by activated or proliferating B cells including MUM1, FOXP1, bcl-2, survivin, protein kinase C-beta (PKC-beta), cyclin D2, cyclin D3, and Ki-67. In univariate analysis, tumor expression of cyclin D2 (P = 0.025) or PKC-beta (P = 0.015) was associated with a worse overall survival, whereas none of the other markers was predictive of overall survival. Patients with DLBCL that expressed either cyclin D2 or PKC-beta had a 5-year overall survival of only 30% as compared to 52% for those who were negative for both markers (P = 0.0019). In multivariate analysis, the expression of cyclin D2 or PKC-beta was an independent predictor of poor overall survival (P = 0.035). Cyclin D2 and PKC-beta expression will be useful in designing a 'biological prognostic index' for patients with DLBCL.

A significant diffuse component predicts for inferior survival in grade 3 follicular lymphoma, but cytologic subtypes do not predict survival.

Grade 3 follicular lymphoma (FL3) is thought to have an aggressive clinical course. On the basis of possible biologic differences, the new World Health Organization (WHO) classification of lymphoma suggests further subdivision of FL3 into grades 3a and 3b and states that the percentage of involvement by diffuse large B-cell lymphoma (DLBCL) should also be reported. However, the clinical implications of these features are unclear. Therefore, we studied 190 newly diagnosed patients with lymph node-based FL3 who received anthracycline-containing combination chemotherapy. The follicular component was subclassified as grade 3a (FL3a) or grade 3b (FL3b) according to the WHO criteria, or as follicular large cleaved cell type (FLC). The percentage of a diffuse component, if present, was also recorded. Of the 190 cases, there were 107 FL3a (56%), 53 FL3b (28%), and 30 FLC (16%) cases. Diffuse areas were seen in 72 cases (31 FL3a, 28 FL3b, and 13 FLC). There were no significant differences in the clinical characteristics, overall survival, or event-free survival between patients with grades FL3a, FL3b, or FLC. However, those cases with a predominant diffuse component (> 50% diffuse) had a significantly worse overall survival (P =.0037) and event-free survival (P =.012). Therefore, we conclude that the subdivision of FL3 into cytologic subtypes does not appear to be important clinically. However, patients with FL3 having a diffuse component of more than 50% have an inferior survival that is similar to the survival of those with DLBCL.

Confirmation of the molecular classification of diffuse large B-cell lymphoma by immunohistochemistry using a tissue microarray.

Diffuse large B-cell lymphoma (DLBCL) can be divided into prognostically important subgroups with germinal center B-cell-like (GCB), activated B-cell-like (ABC), and type 3 gene expression profiles using a cDNA microarray. Tissue microarray (TMA) blocks were created from 152 cases of DLBCL, 142 of which had been successfully evaluated by cDNA microarray (75 GCB, 41 ABC, and 26 type 3). Sections were stained with antibodies to CD10, bcl-6, MUM1, FOXP1, cyclin D2, and bcl-2. Expression of bcl-6 (P <.001) or CD10 (P =.019) was associated with better overall survival (OS), whereas expression of MUM1 (P =.009) or cyclin D2 (P <.001) was associated with worse OS. Cases were subclassified using CD10, bcl-6, and MUM1 expression, and 64 cases (42%) were considered GCB and 88 cases (58%) non-GCB. The 5-year OS for the GCB group was 76% compared with only 34% for the non-GCB group (P <.001), which is similar to that reported using the cDNA microarray. Bcl-2 and cyclin D2 were adverse predictors in the non-GCB group. In multivariate analysis, a high International Prognostic Index score (3-5) and the non-GCB phenotype were independent adverse predictors (P <.0001). In summary, immunostains can be used to determine the GCB and non-GCB subtypes of DLBCL and predict survival similar to the cDNA microarray.

BCL2 translocation defines a unique tumor subset within the germinal center B-cell-like diffuse large B-cell lymphoma.

Gene expression profiling of diffuse large B-cell lymphoma (DLBCL) has revealed prognostically important subgroups: germinal center B-cell-like (GCB) DLBCL, activated B cell-like (ABC) DLBCL, and primary mediastinal large B-cell lymphoma. The t(14;18)(q32;q21) has been reported previously to define a unique subset within the GCB-DLBCL. We evaluated for the translocation in 141 cases of DLBCL that were successfully gene expression profiled. Using a dual-probe fluorescence in situ hybridization assay, we detected the t(14;18) in 17% of DLBCLs and in 34% of the GCB subgroup which contained the vast majority of positive cases. In addition, 12 t(14;18)-positive cases detected by polymerase chain reaction assays on additional samples were added to the fluorescence in situ hybridization-positive cases for subsequent analysis. Immunohistochemical data indicated that BCL2, BCL6, and CD10 protein were preferentially expressed in the t(14;18)-positive cases as compared to t(14;18)-negative cases. Within the GCB subgroup, the expression of BCL2 and CD10, but not BCL6, differed significantly between cases with or without the t(14;18): 88% versus 24% for BCL2 and 72% versus 32% for CD10, respectively. In the GCB-DLBCL subgroup, a heterogeneous group of genes is overexpressed in the t(14;18)-positive subset, among which BCL2 is a significant discriminator. Interestingly, the t(14;18)-negative subset is dominated by overexpression of cell cycle-associated genes, indicating that these tumors are significantly more proliferative, suggesting distinctive pathogenetic mechanisms. However, despite this higher proliferative activity, there was no significant difference in overall or failure-free survival between the t(14;18)-positive and -negative subsets within the GCB subgroup.