RESUMO
(A) Correlation matrix of unsupervised co-regulated genes, based on the 208 genes included in the NanoString platform. Some of the clusters of co-regulated genes corresponded to the following: Inflammatory cells; Epstein-Barr virus; B-cells; Cytotoxic T-cells; T-cells; and Proliferation. (B) Analysis of genomic alterations by targeted sequencing. Distribution of mutations in the 62 analyzed genes. Rows correspond to sequenced genes, columns represent individual patients. Color coding: green, missense; blue, synonymous; pink, frameshift; violet, Indel; red, stop gained; yellow, UTR.
Assuntos
Infecções por Vírus Epstein-Barr , Linfoma Extranodal de Células T-NK , Humanos , Herpesvirus Humano 4/genética , Infecções por Vírus Epstein-Barr/complicações , Infecções por Vírus Epstein-Barr/genética , Infecções por Vírus Epstein-Barr/patologia , Linfoma Extranodal de Células T-NK/terapia , Mutação , Células Matadoras Naturais/patologiaRESUMO
Proliferative nodules (PNs) are benign nodular proliferation of melanocytes occurring within congenital melanocytic naevi (CMN). Differential diagnosis between PN and melanoma is challenging for clinicians and pathologists. We describe the case of a 9-month-old boy who developed multiple nodules arising in a medium-sized CMN. Clinically, pink papules were observed, with dotted vessels on dermoscopy, suggesting spitzoid PN. On histopathological examination, the dermoscopic findings correlated with the vertical vessels of a spitzoid PN. Dermoscopy could be a useful tool to differentiate PN from melanoma. However, further studies describing the dermoscopic features of the different PN subtypes are needed. Histopathology remains the gold standard for definitive diagnosis aided by ancillary molecular tests such as fluorescence in situ hybridization or comparative genomic hybridization.
Assuntos
Melanoma , Nevo de Células Epitelioides e Fusiformes , Nevo Pigmentado , Neoplasias Cutâneas , Hibridização Genômica Comparativa , Diagnóstico Diferencial , Humanos , Hibridização in Situ Fluorescente , Lactente , Masculino , Melanoma/patologia , Nevo Pigmentado/diagnóstico por imagem , Neoplasias Cutâneas/patologiaRESUMO
Oral submucous fibrosis (OSF) is a precancerous condition of the oral cavity associated with habitual chewing of quid, with a high incidence among populations of the Indian subcontinent and Southeast Asia. Clinically, its initial manifestation may mimic oral lichen planus or lichen sclerosus. If the habit is not halted, the mucosa gets leathery and thickened, and fibrous bands form causing significant morbidity. Microscopically, it is characterized by atrophic epithelium, loss of rete ridges, and hyalinization of lamina propria. Of note, these hallmark histopathological features may be overlooked in the unusual presence of lichenoid interface changes, which may lead to the wrong diagnosis. We present herein five cases in which the rare joint appearance of OSF and lichenoid reaction features posed a diagnostic challenge. Due to its progressive nature and malignant potential, the presence of oral lichenoid changes overlying submucous hyalinization, in the right clinical and demographic setting, should raise suspicion of OSF and prompt actions directed at quid-chewing discontinuation.
Assuntos
Erupções Liquenoides/patologia , Fibrose Oral Submucosa/patologia , Lesões Pré-Cancerosas/patologia , Adulto , Areca/efeitos adversos , Feminino , Humanos , Erupções Liquenoides/etiologia , Masculino , Pessoa de Meia-Idade , Fibrose Oral Submucosa/etiologia , Lesões Pré-Cancerosas/etiologia , Tabaco sem Fumaça/efeitos adversosRESUMO
Pediatric-type follicular lymphoma (PTFL) is a variant of follicular lymphoma (FL) with distinctive clinicopathological features. Patients are predominantly young males presenting with localized lymphadenopathy; the tumor shows high-grade cytology and lacks both BCL2 expression and t(14;18) translocation. The genetic alterations involved in the pathogenesis of PTFL are unknown. Therefore, 42 PTFL (40 males and 2 females; mean age, 16 years; range, 5-31) were genetically characterized. For comparison, 11 cases of conventional t(14:18)(-) FL in adults were investigated. Morphologically, PTFL cases had follicular growth pattern without diffuse areas and characteristic immunophenotype. All cases showed monoclonal immunoglobulin (IG) rearrangement. PTFL displays low genomic complexity when compared with t(14;18)(-) FL (mean, 0.77 vs 9 copy number alterations per case; P <001). Both groups presented 1p36 alterations including TNFRSF14, but copy-number neutral loss of heterozygosity (CNN-LOH) of this locus was more frequently observed in PTFL (40% vs 9%; P =075). TNFRSF14 was the most frequently affected gene in PTFL (21 mutations and 2 deletions), identified in 54% of cases, followed by KMT2D mutations in 16%. Other histone-modifying genes were rarely affected. In contrast, t(14;18)(-) FL displayed a mutational profile similar to t(14;18)(+) FL. In 8 PTFL cases (19%), no genetic alterations were identified beyond IG monoclonal rearrangement. The genetic landscape of PTFL suggests that TNFRSF14 mutations accompanied by CNN-LOH of the 1p36 locus in over 70% of mutated cases, as additional selection mechanism, might play a key role in the pathogenesis of this disease. The genetic profiles of PTFL and t(14;18)(-) FL in adults indicate that these are two different disorders.
Assuntos
Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Linfoma Folicular/genética , Mutação/genética , Membro 14 de Receptores do Fator de Necrose Tumoral/genética , Adolescente , Adulto , Criança , Pré-Escolar , Cromossomos Humanos Par 14/genética , Cromossomos Humanos Par 18/genética , Células Clonais , Análise Citogenética , Variações do Número de Cópias de DNA/genética , Análise Mutacional de DNA , Éxons/genética , Feminino , Humanos , Hibridização in Situ Fluorescente , Perda de Heterozigosidade/genética , Linfoma Folicular/patologia , Masculino , Pseudolinfoma , Translocação Genética , Adulto JovemRESUMO
Mucocutaneous candidiasis is a common infection affecting both immunocompetent and immunosuppressed individuals. Diversity in the clinical and histopathological presentation of mucocutaneous candidiasis is well known. However, the occurrence of cutaneous verrucous lesions and giant yeast-like structures has been rarely reported. In this article, we describe a case of disseminated mucocutaneous candidiasis in an immunosuppressed patient who presented as a verrucous plaque on the scrotum with giant Candida blastoconidia. This peculiar presentation expands the clinicopathological spectrum of mucocutaneous candidiasis and highlights the wide range of clinical manifestations and great morphologic variability of this common fungal infection.
Assuntos
Candidíase Mucocutânea Crônica/imunologia , Candidíase Mucocutânea Crônica/patologia , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Hospedeiro Imunocomprometido , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapia , Adolescente , Candida , Humanos , Masculino , Escroto/microbiologia , Escroto/patologia , Esporos FúngicosRESUMO
The chemokine receptor CXCR4 has been implicated in the migration and trafficking of malignant B cells in several haematological malignancies. Over-expression of CXCR4 has been identified in haematological tumours, but data concerning the role of this receptor in diffuse large B cell lymphoma (DLBCL) are lacking. CXCR4 is a marker of poor prognosis in various neoplasms, correlating with metastatic disease and decreased survival of patients. We studied CXCR4 involvement in cell migration in vitro and dissemination in vivo. We also evaluated the prognostic significance of CXCR4 in 94 biopsies of DLBCL patients. We observed that the level of expression of CXCR4 in DLBCL cell lines correlated positively with in vitro migration. Expression of the receptor was also associated with increased engraftment and dissemination, and decreased survival time in NOD/SCID mice. Furthermore, administration of a specific CXCR4 antagonist, AMD3100, decreased dissemination of DLBCL cells in a xenograft mouse model. In addition, we found that CXCR4 expression is an independent prognostic factor for shorter overall survival and progression-free survival in DLBCL patients. These results show that CXCR4 mediates dissemination of DLBCL cells and define for the first time its value as an independent prognostic marker in DLBCL patients.
Assuntos
Movimento Celular/fisiologia , Regulação Neoplásica da Expressão Gênica/fisiologia , Linfoma Difuso de Grandes Células B/mortalidade , Linfoma Difuso de Grandes Células B/fisiopatologia , Receptores CXCR4/fisiologia , Animais , Benzilaminas , Linhagem Celular Tumoral , Ciclamos , Modelos Animais de Doenças , Progressão da Doença , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Compostos Heterocíclicos/farmacologia , Humanos , Técnicas In Vitro , Linfoma Difuso de Grandes Células B/patologia , Masculino , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Pessoa de Meia-Idade , Invasividade Neoplásica/fisiopatologia , Prognóstico , Receptores CXCR4/antagonistas & inibidores , Receptores CXCR4/genética , Taxa de Sobrevida , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Breast carcinomas rarely metastasize to the ovary and are even more rarely present clinically as primary ovarian tumors. However, patients with breast cancer not infrequently develop independent primary ovarian carcinomas. In these cases, distinction between independent primaries and metastatic tumors is crucial. Several comparative immunohistochemical studies have been reported, but few included significant clinicopathologic data and none investigated cases of ovarian and breast carcinomas from the same patients. In this study, we compared 18 cases of patients with bona fide independent breast and ovarian carcinomas (15 high-grade serous and 3 clear cell carcinomas), with 9 cases of patients with known mammary carcinomas (7 lobular and 2 ductal carcinomas) metastatic to the ovary. Immunohistochemical stains for Pax-8, WT-1, and GATA3 were carried out on tissue microarrays (TMA). Most primary ovarian carcinomas were larger than the metastatic tumors (P=0.001) and were diagnosed at an advanced stage. All primary ovarian tumors showed marked nuclear pleomorphism, whereas only 2 metastatic breast carcinomas had Grade 3 nuclei (P=0.000). The vast majority of ovarian metastases (7/9) showed the typical pattern of lobular breast carcinoma. Pax-8 and WT-1 expression were found in 16 of 18 (88%) and 13 of 18 (72%) primary ovarian carcinomas, respectively. In contrast, all primary ovarian carcinomas were negative for GATA3. The 2 Pax-8-negative ovarian carcinomas were also negative for WT-1. With the exception of 3 triple-negative carcinomas, all primary breast carcinomas were positive for GATA3. All metastatic breast carcinomas were positive for GATA3 and negative for Pax-8. WT-1 expression was seen in only 1 of 9 metastatic breast carcinomas (11%). Patients with ovarian metastases had worse prognosis than patients with independent breast and ovarian carcinomas (P=0.000). Pax-8, WT-1, and GATA3 immunoreactions are useful in the distinction between independent primaries and metastatic mammary carcinomas to the ovary in the light of clinicopathologic findings.
Assuntos
Biomarcadores Tumorais/análise , Neoplasias da Mama/diagnóstico , Metástase Neoplásica/diagnóstico , Neoplasias Primárias Múltiplas/diagnóstico , Neoplasias Ovarianas/diagnóstico , Adulto , Idoso , Diagnóstico Diferencial , Feminino , Fator de Transcrição GATA3/análise , Fator de Transcrição GATA3/biossíntese , Humanos , Imuno-Histoquímica , Pessoa de Meia-Idade , Fator de Transcrição PAX8 , Fatores de Transcrição Box Pareados/análise , Fatores de Transcrição Box Pareados/biossíntese , Análise Serial de Tecidos , Proteínas WT1/análise , Proteínas WT1/biossínteseRESUMO
The pattern of myometrial invasion in endometrioid endometrial carcinomas varies considerably; ie, from widely scattered glands and cell nests, often associated with a fibromyxoid stromal reaction (desmoplasia) and/or a lymphocytic infiltrate, to invasive glands with little or no stromal response. Recently, two distinct stromal signatures derived from a macrophage response (colony-stimulating factor 1, CSF1) and a fibroblastic response (desmoid-type fibromatosis, DTF) were identified in breast carcinomas and correlated with clinicopathologic features including outcome. In this study, we explored whether these stromal signatures also apply to endometrioid carcinomas and how their expression patterns correlated with morphologic changes. We studied the stromal signatures both by immunohistochemistry and in situ hybridization in 98 primary endometrioid carcinomas with (87 cases) and without (11 cases) myometrial invasion as well as in the corresponding regional lymph nodes metatases of 9 myoinvasive tumors. Desmoplasia correlated positively with the DTF expression signature. Likewise, mononuclear infiltrates were found in the stroma of tumors expressing CSF1. Twenty-four out of eighty-seven (27%) myoinvasive endometrioid carcinomas were positive for the macrophage signature and thirteen out of eighty-seven (15%) expressed the fibroblast signature. Eleven additional cases were positive for both DTF and CSF1 signatures (11/87; 13%). However, over half of the cases (39/87; 45%) and the majority of the non-myoinvasive tumors (8/11; 73%) failed to express any of the two stromal signatures. The macrophage response (CSF1) was associated with higher tumor grade, lymphovascular invasion, and PIK3CA mutations (P<0.05). There was a concordance in the expression of the CSF1 signature in the primary tumors and their corresponding lymph node metastases. This study is the first characterization of stromal signatures in endometrioid carcinomas. Our findings shed new light on the relationship between genetically different endometrioid carcinomas and various stromal responses. Preservation of the CSF1 macrophage stromal response in the metastases leds support to targeting the CSF1 pathway in endometrioid endometrial carcinomas.
Assuntos
Biomarcadores Tumorais/análise , Carcinoma Endometrioide/química , Neoplasias do Endométrio/química , Fibroblastos/química , Macrófagos/química , Células Estromais/química , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/genética , Carcinoma Endometrioide/genética , Carcinoma Endometrioide/secundário , Classe I de Fosfatidilinositol 3-Quinases , Neoplasias do Endométrio/genética , Neoplasias do Endométrio/patologia , Feminino , Fibroblastos/patologia , Humanos , Imuno-Histoquímica , Hibridização In Situ , Fator Estimulador de Colônias de Macrófagos/análise , Macrófagos/patologia , Pessoa de Meia-Idade , Mutação , Invasividade Neoplásica , Fosfatidilinositol 3-Quinases/genética , Valor Preditivo dos Testes , Células Estromais/patologia , Microambiente TumoralRESUMO
Despite the promising introduction of the proteasome inhibitor bortezomib in the treatment of mantle cell lymphoma (MCL), not all patients respond, and resistance often appears after initial treatment. By analyzing a set of 18 MCL samples, including cell lines with constitutive or induced resistance to bortezomib, we found a high correlation between loss of sensitivity to the proteasome inhibitor and up-regulation of the prosurvival chaperone BiP/Grp78. BiP/Grp78 stabilization was ensured at a posttranscriptional level by an increase in the chaperoning activity of heat shock protein of 90 kDa (Hsp90). In bortezomib-resistant cells, both BiP/Grp78 knockdown and cell pretreatment with the Hsp90 inhibitor of the ansamycin class, IPI-504, led to synergistic induction of apoptotic cell death when combined with bortezomib. Cell exposure to the IPI-504-bortezomib combination provoked the dissociation of Hsp90/BiP complexes, leading to BiP/Grp78 depletion, inhibition of unfolded protein response, and promotion of NOXA-mediated mitochondrial depolarization. The IPI-504-bortezomib combination also prevented BiP/Grp78 accumulation, thereby promoting apoptosis and inhibiting the growth of bortezomib-resistant tumors in a mouse model of MCL xenotransplantation. These results suggest that targeting unfolded protein response activation by the inhibition of Hsp90 may be an attractive model for the design of a new bortezomib-based combination therapy for MCL.
Assuntos
Benzoquinonas/farmacologia , Ácidos Borônicos/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Proteínas de Choque Térmico/genética , Lactamas Macrocíclicas/farmacologia , Linfoma de Célula do Manto/tratamento farmacológico , Pirazinas/uso terapêutico , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Benzoquinonas/uso terapêutico , Bortezomib , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Regulação para Baixo/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos/genética , Chaperona BiP do Retículo Endoplasmático , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Proteínas de Choque Térmico HSP90/antagonistas & inibidores , Proteínas de Choque Térmico/metabolismo , Humanos , Lactamas Macrocíclicas/uso terapêutico , Linfoma de Célula do Manto/genética , Masculino , Camundongos , Camundongos SCID , Camundongos Transgênicos , Pessoa de Meia-Idade , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Receptores de Estrogênio/metabolismo , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de XenoenxertoAssuntos
Antígenos CD8/imunologia , Infecções por HIV/imunologia , Hospedeiro Imunocomprometido , Linfoma Cutâneo de Células T/tratamento farmacológico , Linfoma Cutâneo de Células T/patologia , Idoso , Antirretrovirais/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Autoenxertos , Biópsia por Agulha , Eritema/diagnóstico , Eritema/etiologia , Infecções por HIV/complicações , Infecções por HIV/diagnóstico , Infecções por HIV/tratamento farmacológico , Transplante de Células-Tronco Hematopoéticas/métodos , Humanos , Imuno-Histoquímica , Linfoma Cutâneo de Células T/complicações , Linfoma Cutâneo de Células T/diagnóstico , Prognóstico , Medição de Risco , Resultado do TratamentoRESUMO
Activation of the endoplasmic reticulum (ER) stress pathway is associated with poor response to doxorubicin-containing regimens, such as rituximab, cyclophosphamide, hydroxydaunorubicin (doxorubicin), vincristine and prednisone (R-CHOP), in patients with diffuse large B-cell lymphoma (DLBCL). Bortezomib, a proteasome inhibitor, interferes with ER responses and improves survival in patients with aggressive hematologic malignant tumors, although its use in DLBCL patients remains controversial. The 78-kDa glucose-regulated protein (GRP78), also known as immunoglobulin heavy chain binding protein (BiP), is an ER stress sensor involved in the resistance to doxorubicin and bortezomib, but its role in the response to chemotherapy in DLBCL has not been explored before. We show that high BiP/GRP78 expression is related to worse overall survival (median overall survival, 5.2 versus 3.4 years). Moreover, cell death after R-CHOP in DLCBL cell lines is associated with decreased BiP/GRP78 expression. Conversely, DLBCL cell lines are primarily resistant to bortezomib, probably owing to BiP/GRP78 overexpression. Small-interfering RNA silencing of BiP/GRP78 renders all cell lines sensitive to bortezomib. R-CHOP with bortezomib (R-CHOP-BZ) reduces BiP/GRP78 expression and overcomes bortezomib resistance, mimicking the small-interfering RNA silencing of BiP/GRP78. Accordingly, R-CHOP-BZ is the most effective treatment, providing a rationale for the use of this combinational therapy to improve DLBCL patient survival. Moreover, this study provides preclinical evidence that the germinal center B-cell-like subtype DLBCL is sensitive to bortezomib combined with immunochemotherapy.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Linfoma Difuso de Grandes Células B/tratamento farmacológico , Inibidores de Proteases/uso terapêutico , Receptores de Neuropeptídeos/metabolismo , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Ácidos Borônicos/administração & dosagem , Bortezomib , Linhagem Celular Tumoral , Ciclofosfamida/administração & dosagem , Regulação para Baixo , Doxorrubicina/administração & dosagem , Resistencia a Medicamentos Antineoplásicos , Chaperona BiP do Retículo Endoplasmático , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prednisona/administração & dosagem , Pirazinas/administração & dosagem , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/fisiologia , Análise de Sobrevida , Resultado do Tratamento , Resposta a Proteínas não Dobradas/efeitos dos fármacos , Vincristina/administração & dosagem , Adulto JovemRESUMO
Recently, mutation of the FOXL2 gene has been consistently identified in adult granulosa cell tumors of the ovary. The purpose of this study is to investigate whether the FOXL2 mutation and mRNA expression have a role in the pathogenesis of juvenile and adult granulosa cell tumors and influence tumor progression. Thirty-four adult granulosa cell tumors and 20 juvenile granulosa cell tumors were examined for the presence of the FOXL2 (C402G) mutation. Expression levels were studied by quantitative PCR and immunohistochemistry. We found that FOXL2 (C402G) mutation was present in 19/27 (70%) of the adult type tumors but in none of the juvenile granulosa cell tumors (0/18). No correlation was encountered between the presence of FOXL2 mutation and various clinicopathologic parameters except for the presence of a different sex-cord component, which was more frequently found in the subgroup of wild-type adult granulosa cell tumors than in the mutated tumors. Patients with tumors harboring the FOXL2 (C402G) mutation had a worse disease-free survival than those with the wild-type gene. Expression levels of FOXL2 mRNA had an impact on disease-free survival in both adult and juvenile granulosa cell tumors. We also found that the mutated tumors had a higher immunohistochemical expression of the FOXL2 protein, and there was a linear correlation between mRNA and immunohistochemical FOXL2 expression in both adult and juvenile granulosa cell tumors. Patients with juvenile granulosa cell tumors and higher FOXL2 protein expression had worse overall survival and disease-free survival than those with negative or weakly immunoreactive tumors. Our data suggest that FOXL2 mutation and mRNA expression are of prognostic importance in both adult and juvenile granulosa cell tumors.
Assuntos
Biomarcadores Tumorais/genética , Fatores de Transcrição Forkhead/genética , Tumor de Células da Granulosa/genética , Mutação , Neoplasias Ovarianas/genética , RNA Mensageiro/análise , Adolescente , Adulto , Fatores Etários , Idoso , Biomarcadores Tumorais/análise , Análise Mutacional de DNA , Intervalo Livre de Doença , Feminino , Proteína Forkhead Box L2 , Fatores de Transcrição Forkhead/análise , Tumor de Células da Granulosa/química , Tumor de Células da Granulosa/mortalidade , Tumor de Células da Granulosa/patologia , Humanos , Imuno-Histoquímica , Estimativa de Kaplan-Meier , Pessoa de Meia-Idade , Neoplasias Ovarianas/química , Neoplasias Ovarianas/mortalidade , Neoplasias Ovarianas/patologia , Reação em Cadeia da Polimerase , Prognóstico , Modelos de Riscos Proporcionais , Taxa de Sobrevida , Fatores de Tempo , Regulação para Cima , Adulto JovemRESUMO
Generalized pustular psoriasis (GPP) represents the rarest form of psoriasis, which may be potentially fatal. In the last decade, (likely) pathogenic variants in the IL36RN, CARD14 and AP1S3 genes have been associated with monogenic GPP forms. Despite these advances, the genetic basis of most patients with GPP remains unidentified. Treatment of GPP patients is often difficult, with no consensus about the best available options to date. We report herein an infant with severe GPP in whom the disease started at the age of 2 months. Genetic investigations identified a heterozygous pathogenic variant in the IL36RN gene associated with a heterozygous variant of uncertain significance in the CARD14 gene. After previous treatment failures with acitretin, cyclosporin and anakinra, treatment with the interleukin-17 antagonist secukinumab resulted in a dramatic and prompt positive response that persisted at 12-month follow up. According to our experience, we believe secukinumab can be an effective and safe treatment for pediatric patients with GPP even before 1 year of age.
Assuntos
Interleucinas , Psoríase , Anticorpos Monoclonais Humanizados , Proteínas Adaptadoras de Sinalização CARD/genética , Criança , Guanilato Ciclase/genética , Humanos , Lactente , Interleucinas/genética , Proteínas de Membrana/genética , Mutação , Psoríase/tratamento farmacológico , Psoríase/genéticaRESUMO
X box-binding protein 1 (Xbp-1) is a transcription factor that is required for the terminal differentiation of B lymphocytes into plasma cells. The Xbp-1 gene is activated in response to endoplasmic reticulum stress signals, which generate a 50-kDa nuclear protein that acts as a potent transactivator and regulates the expression of genes related to the unfolded protein response. Activated Xbp-1 is essential for cell survival in plasma-cell tumors but its role in B-cell lymphomas is unknown. We analyzed the expression of activated Xbp-1 in reactive lymphoid tissues, 411 lymphomas and plasma-cell neoplasms, and 24 B-cell lines. In reactive tissues, Xbp-1 was only found in nuclear extracts. Nuclear expression of Xbp-1 was observed in occasional reactive plasma cells and in a subpopulation of Irf-4(+)/Bcl-6(-)/Pax-5(-) B cells in the light zones of reactive germinal centers, probably representing cells committed to plasma-cell differentiation. None of the low-grade lymphomas showed evidence of Xbp-1 activation; however, Xbp-1 activation was found in 28% of diffuse large B-cell lymphomas, independent of germinal or postgerminal center phenotype, as well as in 48% of plasmablastic lymphomas and 69% of plasma-cell neoplasms. Diffuse large B-cell lymphomas with nuclear Xbp-1 expression had a significantly worse response to therapy and shorter overall survival compared with negative tumors. These findings suggest that Xbp-1 activation may play a role in the pathogenesis of aggressive B-cell lymphomas.