Juan Rosai as master of our comprehensive understanding of thymus and thymoma.

In this study, the authors report on the activity of Juan Rosai, one of the pathologists most engaged in the definition of cells, diseases and tumors occurring in the thymus and in the mediastinum during the last 60 years. With his morphological skills and tireless interest in clarification of disease patterns, he contributed extraordinarily to expand our knowledge of the mediastinal diseases and to improve our diagnostic approach. He determined extraordinary advances also in trasmission electron microscopy and in immunohistochemistry as powerful diagnostic tools. Moreover, he proposed and promoted, together with an international panel of Pathologists, the World Health Classification of Thymic tumors as a definite progress in our comprehension and diagnostics of thymic epithelial tumors (TET). Our purpose is to review J. Rosai's achievements in thymic normal structure, in TET and particularly in the entity now definied as "thymoma", in distinction from the thymic carcinoma. To do this, our narrative will also be based on personal memories, longstanding collaborations and/or friendship with J. Rosai.

Interference with ERK-dimerization at the nucleocytosolic interface targets pathological ERK1/2 signaling without cardiotoxic side-effects.

Dysregulation of extracellular signal-regulated kinases (ERK1/2) is linked to several diseases including heart failure, genetic syndromes and cancer. Inhibition of ERK1/2, however, can cause severe cardiac side-effects, precluding its wide therapeutic application. ERKT188-autophosphorylation was identified to cause pathological cardiac hypertrophy. Here we report that interference with ERK-dimerization, a prerequisite for ERKT188-phosphorylation, minimizes cardiac hypertrophy without inducing cardiac adverse effects: an ERK-dimerization inhibitory peptide (EDI) prevents ERKT188-phosphorylation, nuclear ERK1/2-signaling and cardiomyocyte hypertrophy, protecting from pressure-overload-induced heart failure in mice whilst preserving ERK1/2-activity and cytosolic survival signaling. We also examine this alternative ERK1/2-targeting strategy in cancer: indeed, ERKT188-phosphorylation is strongly upregulated in cancer and EDI efficiently suppresses cancer cell proliferation without causing cardiotoxicity. This powerful cardio-safe strategy of interfering with ERK-dimerization thus combats pathological ERK1/2-signaling in heart and cancer, and may potentially expand therapeutic options for ERK1/2-related diseases, such as heart failure and genetic syndromes.

A modular transcriptome map of mature B cell lymphomas.

BACKGROUND: Germinal center-derived B cell lymphomas are tumors of the lymphoid tissues representing one of the most heterogeneous malignancies. Here we characterize the variety of transcriptomic phenotypes of this disease based on 873 biopsy specimens collected in the German Cancer Aid MMML (Molecular Mechanisms in Malignant Lymphoma) consortium. They include diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), Burkitt's lymphoma, mixed FL/DLBCL lymphomas, primary mediastinal large B cell lymphoma, multiple myeloma, IRF4-rearranged large cell lymphoma, MYC-negative Burkitt-like lymphoma with chr. 11q aberration and mantle cell lymphoma. METHODS: We apply self-organizing map (SOM) machine learning to microarray-derived expression data to generate a holistic view on the transcriptome landscape of lymphomas, to describe the multidimensional nature of gene regulation and to pursue a modular view on co-expression. Expression data were complemented by pathological, genetic and clinical characteristics. RESULTS: We present a transcriptome map of B cell lymphomas that allows visual comparison between the SOM portraits of different lymphoma strata and individual cases. It decomposes into one dozen modules of co-expressed genes related to different functional categories, to genetic defects and to the pathogenesis of lymphomas. On a molecular level, this disease rather forms a continuum of expression states than clearly separated phenotypes. We introduced the concept of combinatorial pattern types (PATs) that stratifies the lymphomas into nine PAT groups and, on a coarser level, into five prominent cancer hallmark types with proliferation, inflammation and stroma signatures. Inflammation signatures in combination with healthy B cell and tonsil characteristics associate with better overall survival rates, while proliferation in combination with inflammation and plasma cell characteristics worsens it. A phenotypic similarity tree is presented that reveals possible progression paths along the transcriptional dimensions. Our analysis provided a novel look on the transition range between FL and DLBCL, on DLBCL with poor prognosis showing expression patterns resembling that of Burkitt's lymphoma and particularly on 'double-hit' MYC and BCL2 transformed lymphomas. CONCLUSIONS: The transcriptome map provides a tool that aggregates, refines and visualizes the data collected in the MMML study and interprets them in the light of previous knowledge to provide orientation and support in current and future studies on lymphomas and on other cancer entities.

Fatal Human Meningoencephalitis due to Halicephalobus Nematodes, Germany.

Infections with Halicephalobus nematodes, causative agents of severe meningoencephalitis in horses, have rarely been reported in humans. In this study, the clinical, serological, cytokine, and histopathological findings of a rapidly progressive and eventually fatal meningoencephalitis in a previously healthy human are described. The helminth was finally diagnosed by specific polymerase chain reactions from post mortem tissue.

Late-onset myasthenia gravis - CTLA4(low) genotype association and low-for-age thymic output of naïve T cells.

Late-onset myasthenia gravis (LOMG) has become the largest MG subgroup, but the underlying pathogenetic mechanisms remain mysterious. Among the few etiological clues are the almost unique serologic parallels between LOMG and thymoma-associated MG (TAMG), notably autoantibodies against acetylcholine receptors, titin, ryanodine receptor, type I interferons or IL-12. This is why we checked LOMG patients for two further peculiar features of TAMG - its associations with the CTLA4(high/gain-of-function) +49A/A genotype and with increased thymic export of naïve T cells into the blood, possibly after defective negative selection in AIRE-deficient thymomas. We analyzed genomic DNA from 116 Caucasian LOMG patients for CTLA4 alleles by PCR/restriction fragment length polymorphism, and blood mononuclear cells for recent thymic emigrants by quantitative PCR for T cell receptor excision circles. In sharp contrast with TAMG, we now find that: i) CTLA4(low) +49G(+) genotypes were more frequent (p = 0.0029) among the 69 LOMG patients with age at onset ≥60 years compared with 172 healthy controls; ii) thymic export of naïve T cells from the non-neoplastic thymuses of 36 LOMG patients was lower (p = 0.0058) at diagnosis than in 77 age-matched controls. These new findings are important because they suggest distinct initiating mechanisms in TAMG and LOMG and hint at aberrant immuno-regulation in the periphery in LOMG. We therefore propose alternate defects in central thymic or peripheral tolerance induction in TAMG and LOMG converging on similar final outcomes. In addition, our data support a 60-year-threshold for onset of 'true LOMG' and an LOMG/early-onset MG overlapping group of patients between 40 and 60.

Anti-Apoptotic Signature in Thymic Squamous Cell Carcinomas - Functional Relevance of Anti-Apoptotic BIRC3 Expression in the Thymic Carcinoma Cell Line 1889c.

The molecular pathogenesis of thymomas and thymic carcinomas (TCs) is poorly understood and results of adjuvant therapy are unsatisfactory in case of metastatic disease and tumor recurrence. For these clinical settings, novel therapeutic strategies are urgently needed. Recently, limited sequencing efforts revealed that a broad spectrum of genes that play key roles in various common cancers are rarely affected in thymomas and TCs, suggesting that other oncogenic principles might be important. This made us re-analyze historic expression data obtained in a spectrum of thymomas and thymic squamous cell carcinomas (TSCCs) with a custom-made cDNA microarray. By cluster analysis, different anti-apoptotic signatures were detected in type B3 thymoma and TSCC, including overexpression of BIRC3 in TSCCs. This was confirmed by qRT-PCR in the original and an independent validation set of tumors. In contrast to several other cancer cell lines, the BIRC3-positive TSCC cell line, 1889c showed spontaneous apoptosis after BIRC3 knock-down. Targeting apoptosis genes is worth testing as therapeutic principle in TSCC.

Burkitt lymphoma pathogenesis and therapeutic targets from structural and functional genomics.

Burkitt's lymphoma (BL) can often be cured by intensive chemotherapy, but the toxicity of such therapy precludes its use in the elderly and in patients with endemic BL in developing countries, necessitating new strategies. The normal germinal centre B cell is the presumed cell of origin for both BL and diffuse large B-cell lymphoma (DLBCL), yet gene expression analysis suggests that these malignancies may use different oncogenic pathways. BL is subdivided into a sporadic subtype that is diagnosed in developed countries, the Epstein-Barr-virus-associated endemic subtype, and an HIV-associated subtype, but it is unclear whether these subtypes use similar or divergent oncogenic mechanisms. Here we used high-throughput RNA sequencing and RNA interference screening to discover essential regulatory pathways in BL that cooperate with MYC, the defining oncogene of this cancer. In 70% of sporadic BL cases, mutations affecting the transcription factor TCF3 (E2A) or its negative regulator ID3 fostered TCF3 dependency. TCF3 activated the pro-survival phosphatidylinositol-3-OH kinase pathway in BL, in part by augmenting tonic B-cell receptor signalling. In 38% of sporadic BL cases, oncogenic CCND3 mutations produced highly stable cyclin D3 isoforms that drive cell cycle progression. These findings suggest opportunities to improve therapy for patients with BL.

State-of-the-art classification and multimodality treatment of malignant thymoma.

Thymomas are the most common tumors of the anterior mediastinum. Classification, treatment options and understanding of the pathophysiology of thymoma have changed over the past years. It is hoped that novel therapeutic strategies will lead to a survival benefit in these patients. It has turned out that patients with thymoma are best treated with multimodality therapy. In this review, a pathologist, an immunologist, a surgeon, a radiotherapist, a pneumologist and oncologists discuss the current status of classification and strategies for the treatment of thymoma patients.

Oncogenically active MYD88 mutations in human lymphoma.

The activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) remains the least curable form of this malignancy despite recent advances in therapy. Constitutive nuclear factor (NF)-κB and JAK kinase signalling promotes malignant cell survival in these lymphomas, but the genetic basis for this signalling is incompletely understood. Here we describe the dependence of ABC DLBCLs on MYD88, an adaptor protein that mediates toll and interleukin (IL)-1 receptor signalling, and the discovery of highly recurrent oncogenic mutations affecting MYD88 in ABC DLBCL tumours. RNA interference screening revealed that MYD88 and the associated kinases IRAK1 and IRAK4 are essential for ABC DLBCL survival. High-throughput RNA resequencing uncovered MYD88 mutations in ABC DLBCL lines. Notably, 29% of ABC DLBCL tumours harboured the same amino acid substitution, L265P, in the MYD88 Toll/IL-1 receptor (TIR) domain at an evolutionarily invariant residue in its hydrophobic core. This mutation was rare or absent in other DLBCL subtypes and Burkitt's lymphoma, but was observed in 9% of mucosa-associated lymphoid tissue lymphomas. At a lower frequency, additional mutations were observed in the MYD88 TIR domain, occurring in both the ABC and germinal centre B-cell-like (GCB) DLBCL subtypes. Survival of ABC DLBCL cells bearing the L265P mutation was sustained by the mutant but not the wild-type MYD88 isoform, demonstrating that L265P is a gain-of-function driver mutation. The L265P mutant promoted cell survival by spontaneously assembling a protein complex containing IRAK1 and IRAK4, leading to IRAK4 kinase activity, IRAK1 phosphorylation, NF-κB signalling, JAK kinase activation of STAT3, and secretion of IL-6, IL-10 and interferon-ß. Hence, the MYD88 signalling pathway is integral to the pathogenesis of ABC DLBCL, supporting the development of inhibitors of IRAK4 kinase and other components of this pathway for the treatment of tumours bearing oncogenic MYD88 mutations.

Cooperative epigenetic modulation by cancer amplicon genes.

Chromosome band 9p24 is frequently amplified in primary mediastinal B cell lymphoma (PMBL) and Hodgkin lymphoma (HL). To identify oncogenes in this amplicon, we screened an RNA interference library targeting amplicon genes and thereby identified JAK2 and the histone demethylase JMJD2C as essential genes in these lymphomas. Inhibition of JAK2 and JMJD2C cooperated in killing these lymphomas by decreasing tyrosine 41 phosphorylation and increasing lysine 9 trimethylation of histone H3, promoting heterochromatin formation. MYC, a major target of JAK2-mediated histone phosphorylation, was silenced after JAK2 and JMJD2C inhibition, with a corresponding increase in repressive chromatin. Hence, JAK2 and JMJD2C cooperatively remodel the PMBL and HL epigenome, offering a mechanistic rationale for the development of JAK2 and JMJD2C inhibitors in these diseases.

Reduced treatment intensity in patients with early-stage Hodgkin's lymphoma.

BACKGROUND: Whether it is possible to reduce the intensity of treatment in early (stage I or II) Hodgkin's lymphoma with a favorable prognosis remains unclear. We therefore conducted a multicenter, randomized trial comparing four treatment groups consisting of a combination chemotherapy regimen of two different intensities followed by involved-field radiation therapy at two different dose levels. METHODS: We randomly assigned 1370 patients with newly diagnosed early-stage Hodgkin's lymphoma with a favorable prognosis to one of four treatment groups: four cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) followed by 30 Gy of radiation therapy (group 1), four cycles of ABVD followed by 20 Gy of radiation therapy (group 2), two cycles of ABVD followed by 30 Gy of radiation therapy (group 3), or two cycles of ABVD followed by 20 Gy of radiation therapy (group 4). The primary end point was freedom from treatment failure; secondary end points included efficacy and toxicity of treatment. RESULTS: The two chemotherapy regimens did not differ significantly with respect to freedom from treatment failure (P=0.39) or overall survival (P=0.61). At 5 years, the rates of freedom from treatment failure were 93.0% (95% confidence interval [CI], 90.5 to 94.8) with the four-cycle ABVD regimen and 91.1% (95% CI, 88.3 to 93.2) with the two-cycle regimen. When the effects of 20-Gy and 30-Gy doses of radiation therapy were compared, there were also no significant differences in freedom from treatment failure (P=1.00) or overall survival (P=0.61). Adverse events and acute toxic effects of treatment were most common in the patients who received four cycles of ABVD and 30 Gy of radiation therapy (group 1). CONCLUSIONS: In patients with early-stage Hodgkin's lymphoma and a favorable prognosis, treatment with two cycles of ABVD followed by 20 Gy of involved-field radiation therapy is as effective as, and less toxic than, four cycles of ABVD followed by 30 Gy of involved-field radiation therapy. Long-term effects of these treatments have not yet been fully assessed. (Funded by the Deutsche Krebshilfe and the Swiss Federal Government; ClinicalTrials.gov number, NCT00265018.)

Immunoblastic morphology but not the immunohistochemical GCB/nonGCB classifier predicts outcome in diffuse large B-cell lymphoma in the RICOVER-60 trial of the DSHNHL.

The survival of diffuse large B-cell lymphoma patients varies considerably, reflecting the molecular diversity of tumors. In view of the controversy whether cytologic features, immunohistochemical markers or gene expression signatures may capture this molecular diversity, we investigated which features provide prognostic information in a prospective trial in the R-CHOP treatment era. Within the cohort of DLBCLs patients treated in the RICOVER-60 trial of the German High-Grade Lymphoma Study Group (DSHNHL), we tested the prognostic impact of IB morphology in 949 patients. The expression of immunohistochemical markers CD5, CD10, BCL2, BCL6, human leukocyte antigen (HLA)-DR, interferon regulatory factor-4/multiple myeloma-1 (IRF4/MUM1), and Ki-67 was assessed in 506 patients. Expression of the immunohistochemical markers tested was of modest, if any, prognostic relevance. Moreover, the Hans algorithm using the expression patterns of CD10, BCL6, and interferon regulatory factor-4/multiple myeloma-1 failed to show prognostic significance in the entire cohort as well as in patient subgroups. IB morphology, however, emerged as a robust, significantly adverse prognostic factor in multivariate analysis, and its diagnosis showed a good reproducibility among expert hematopathologists. We conclude, therefore, that IB morphology in DLBCL is likely to capture some of the adverse molecular alterations that are currently not detectable in a routine diagnostic setting, and that its recognition has significant prognostic power.

Intensified chemotherapy and dose-reduced involved-field radiotherapy in patients with early unfavorable Hodgkin's lymphoma: final analysis of the German Hodgkin Study Group HD11 trial.

PURPOSE: Combined-modality treatment consisting of four to six cycles of chemotherapy followed by involved-field radiotherapy (IFRT) is the standard of care for patients with early unfavorable Hodgkin's lymphoma (HL). It is unclear whether treatment results can be improved with more intensive chemotherapy and which radiation dose needs to be applied. PATIENTS AND METHODS: Patients age 16 to 75 years with newly diagnosed early unfavorable HL were randomly assigned in a 2 × 2 factorial design to one of the following treatment arms: four cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) + 30 Gy of IFRT; four cycles of ABVD + 20 Gy of IFRT; four cycles of bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (BEACOPP(baseline)) + 30 Gy of IFRT; or four cycles of BEACOPP(baseline) + 20 Gy of IFRT. RESULTS: With a total of 1,395 patients included, the freedom from treatment failure (FFTF) at 5 years was 85.0%, overall survival was 94.5%, and progression-free survival was 86.0%. BEACOPP(baseline) was more effective than ABVD when followed by 20 Gy of IFRT (5-year FFTF difference, 5.7%; 95% CI, 0.1% to 11.3%). However, there was no difference between BEACOPP(baseline) and ABVD when followed by 30 Gy of IFRT (5-year FFTF difference, 1.6%; 95% CI, -3.6% to 6.9%). Similar results were observed for the radiotherapy question; after four cycles of BEACOPP(baseline), 20 Gy was not inferior to 30 Gy (5-year FFTF difference, -0.8%; 95% CI, -5.8% to 4.2%), whereas inferiority of 20 Gy cannot be excluded after four cycles of ABVD (5-year FFTF difference, -4.7%; 95% CI, -10.3% to 0.8%). Treatment-related toxicity occurred more often in the arms with more intensive therapy. CONCLUSION: Moderate dose escalation using BEACOPP(baseline) did not significantly improve outcome in early unfavorable HL. Four cycles of ABVD should be followed by 30 Gy of IFRT.

Disturbed expression of the T-cell receptor/CD3 complex and associated signaling molecules in CD30+ T-cell lymphoproliferations.

BACKGROUND: CD30(+) T-cell lymphoproliferations comprise a spectrum of clinically heterogeneous entities, including systemic anaplastic large cell lymphomas (ALK(-) and ALK(+)) and primary cutaneous CD30(+) T-cell lymphoproliferative disorders. While all these entities are characterized by proliferation of highly atypical, anaplastic CD30(+) T cells, the expression of T-cell specific antigens in the tumor cells is not consistently detectable. DESIGN AND METHODS: We evaluated biopsies from 19 patients with primary cutaneous CD30(+) lymphoproliferative disorders, 38 with ALK(-) and 33 with ALK(+) systemic anaplastic large cell lymphoma. The biopsies were examined for the expression of T-cell receptorαß/CD3 complex (CD3γ, δ, ε, ζ), transcription factors regulating T-cell receptor expression (ATF1, ATF2, TCF-1, TCF-1α/LEF-1, Ets1), and molecules of T-cell receptor-associated signaling cascades (Lck, ZAP-70, LAT, bcl-10, Carma1, NFATc1, c-Jun, c-Fos, Syk) using immunohistochemistry. RESULTS: In comparison to the pattern in 20 peripheral T-cell lymphomas, not otherwise specified, we detected a highly disturbed expression of the T-cell receptor/CD3 complex, TCF-1, TCF-1α/LEF-1, Lck, ZAP-70, LAT, NFATc1, c-Jun, c-Fos and Syk in most of the systemic anaplastic large cell lymphomas. In addition, primary cutaneous CD30(+) lymphoproliferative disorders showed such a similar expression pattern to that of systemic anaplastic large cell lymphomas, that none of the markers we investigated can reliably distinguish between these CD30(+) T-cell lymphoproliferations. CONCLUSIONS: Severely altered expression of the T-cell receptor/CD3 complex, T-cell receptor-associated transcription factors and signal transduction molecules is a common characteristic of systemic and cutaneous CD30(+) lymphoproliferations, although the clinical behavior of these entities is very different. Since peripheral T-cell lymphomas, not otherwise specified retain the full expression program required for functioning T-cell receptor signaling, the differential expression of a subset of these markers might be of diagnostic utility in distinguishing peripheral T-cell lymphomas, not otherwise specified from the entire group of CD30(+) lymphoproliferations.

Tumor-associated macrophages and survival in classic Hodgkin's lymphoma.

BACKGROUND: Despite advances in treatments for Hodgkin's lymphoma, about 20% of patients still die from progressive disease. Current prognostic models predict the outcome of treatment with imperfect accuracy, and clinically relevant biomarkers have not been established to improve on the International Prognostic Score. METHODS: Using gene-expression profiling, we analyzed 130 frozen samples obtained from patients with classic Hodgkin's lymphoma during diagnostic lymph-node biopsy to determine which cellular signatures were correlated with treatment outcome. We confirmed our findings in an independent cohort of 166 patients, using immunohistochemical analysis. RESULTS: Gene-expression profiling identified a gene signature of tumor-associated macrophages that was significantly associated with primary treatment failure (P=0.02). In an independent cohort of patients, we found that an increased number of CD68+ macrophages was correlated with a shortened progression-free survival (P=0.03) and with an increased likelihood of relapse after autologous hematopoietic stem-cell transplantation (P=0.008), resulting in shortened disease-specific survival (P=0.003). In multivariate analysis, this adverse prognostic factor outperformed the International Prognostic Score for disease-specific survival (P=0.003 vs. P=0.03). The absence of an elevated number of CD68+ cells in patients with limited-stage disease defined a subgroup of patients with a long-term disease-specific survival of 100% with the use of current treatment strategies. CONCLUSIONS: An increased number of tumor-associated macrophages was strongly associated with shortened survival in patients with classic Hodgkin's lymphoma and provides a new biomarker for risk stratification.

Gene expression profiling uncovers molecular classifiers for the recognition of anaplastic large-cell lymphoma within peripheral T-cell neoplasms.

PURPOSE: To unravel the regulatory network underlying nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) -mediated lymphomagenesis of anaplastic large-cell lymphoma (ALCL) and to discover diagnostic genomic classifiers for the recognition of patients with ALK-positive and ALK-negative ALCL among T-cell non-Hodgkin's lymphoma (T-NHL). PATIENTS AND METHODS: The transcriptome of NPM-ALK-positive ALCL cell lines was characterized by silencing the expression of ALK or STAT3, a major effector of ALK oncogenic activity. Gene expression profiling (GEP) was performed in a series of systemic primary T-NHL (n = 70), including a set of ALK-positive and ALK-negative ALCL (n = 36). Genomic classifiers for ALK-positive and ALK-negative ALCL were generated by prediction analyses and validated by quantitative reverse-transcriptase polymerase chain reaction and/or immunohistochemistry. RESULTS: In ALCL cell lines, two thirds of ALK-regulated genes were concordantly dependent on STAT3 expression. GEP of systemic primary T-NHL significantly clustered ALK-positive ALCL samples in a separate subgroup, underscoring the relevance of in vitro ALK/STAT3 signatures. A set of genomic classifiers for ALK-positive ALCL and for ALCL were identified by prediction analyses. These gene clusters were instrumental for the distinction of ALK-negative ALCL from peripheral T-cell lymphomas not otherwise specified (PTCLs-NOS) and angioimmunoblastic lymphomas. CONCLUSION: We proved that experimentally controlled GEP in ALCL cell lines represents a powerful tool to identify meaningful signaling networks for the recognition of systemic primary T-NHL. The identification of a molecular signature specific for ALCL suggests that these T-NHLs may represent a unique entity discernible from other PTCLs, and that a restricted number of genes can be instrumental for clinical stratification and, possibly, therapy of T-NHL.

Chronic active B-cell-receptor signalling in diffuse large B-cell lymphoma.

A role for B-cell-receptor (BCR) signalling in lymphomagenesis has been inferred by studying immunoglobulin genes in human lymphomas and by engineering mouse models, but genetic and functional evidence for its oncogenic role in human lymphomas is needed. Here we describe a form of 'chronic active' BCR signalling that is required for cell survival in the activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL). The signalling adaptor CARD11 is required for constitutive NF-kappaB pathway activity and survival in ABC DLBCL. Roughly 10% of ABC DLBCLs have mutant CARD11 isoforms that activate NF-kappaB, but the mechanism that engages wild-type CARD11 in other ABC DLBCLs was unknown. An RNA interference genetic screen revealed that a BCR signalling component, Bruton's tyrosine kinase, is essential for the survival of ABC DLBCLs with wild-type CARD11. In addition, knockdown of proximal BCR subunits (IgM, Ig-kappa, CD79A and CD79B) killed ABC DLBCLs with wild-type CARD11 but not other lymphomas. The BCRs in these ABC DLBCLs formed prominent clusters in the plasma membrane with low diffusion, similarly to BCRs in antigen-stimulated normal B cells. Somatic mutations affecting the immunoreceptor tyrosine-based activation motif (ITAM) signalling modules of CD79B and CD79A were detected frequently in ABC DLBCL biopsy samples but rarely in other DLBCLs and never in Burkitt's lymphoma or mucosa-associated lymphoid tissue lymphoma. In 18% of ABC DLBCLs, one functionally critical residue of CD79B, the first ITAM tyrosine, was mutated. These mutations increased surface BCR expression and attenuated Lyn kinase, a feedback inhibitor of BCR signalling. These findings establish chronic active BCR signalling as a new pathogenetic mechanism in ABC DLBCL, suggesting several therapeutic strategies.

Leiomyosarcoma of the larynx as a local relapse of squamous cell carcinoma--report of an unusual case.

BACKGROUND: The authors report on leiomyosarcoma after previously treated squamous cell carcinoma (SCC) at the glottis. METHODS: Primary tumor and relapses were investigated morphologically, immunohistochemically, and with molecular methods. RESULTS: The SCC was typical, but few cells showed a spindle-shaped pattern. The relapse tumor was a spindle-shaped and epitheloid tumor with the morphological and immunohistochemical appearance of leiomyosarcoma (sm-actin+, desmin+, caldesmon+, vimentin+, keratin-).The comparative genomic hybridization (CGH) revealed some gains and losses in the leiomyosarcoma. Because of altered material, the investigation failed in the primary. A fluorescence in situ hybridization (5p) focally detected 3 chromosmomal copies, corresponding to gains on 5p in CGH of leiomyosarcoma. CONCLUSION: Leiomyosarcoma after SCC is very uncommon. A connection between both seems likely in this case. Transdifferentiation, also seen in other tumors or carcinosarcomas, could be based on aberrant differentiation of a pluripotent stem cell.

Laryngeal inflammatory myofibroblastic tumors: Different clinical appearance and histomorphologic presentation of one entity.

BACKGROUND: Inflammatory myofibroblastic tumors (IMFTs) of the larynx are rare. We report the clinical presentation, histomorphology, and new molecular findings of 2 cases. METHODS: Paraffin-embedded specimens were stained immunohistochemically (eg, vimentin, AE1/3, Alk-1, smooth muscle [sm-]actin, p53, Rb1, immunoglobulin G4 [IgG4]). Epstein-Barr virus-encoded RNA (EBER) in situ hybridization and HHV8-polymerase chain reaction (PCR) were done. Comparative genomic hybridization (CGH) was performed. RESULTS: Case 1 was that of a 56-year-old man with an infiltrating plasma-cell-rich tumor (Alk-1-, sm-actin+). Plasma cells were strongly positive for IgG4. CGH was unsuspicious. Case 2 was that of a 34-year-old woman with an exophytic tumor (Alk-1+). CGH revealed losses on 13q14-22. The few plasma cells were negative for IgG4. The proliferation (Ki67) was low in both cases. CONCLUSION: Different types of IMFTs may exist and could indicate different therapeutic strategies. Alk-1-positive cases with only scattered inflammatory cells could represent the neoplastic variant, whereas cases rich in plasma cells could be associated with IgG4 sclerosing diseases.

Association of chronic non-bacterial osteomyelitis with Crohn's disease but not with CARD15 gene variants.

Chronic non-bacterial osteomyelitis (CNO) is an inflammatory, non-infectious disorder of the skeletal system with unknown etiology. Besides bone-inflammation, patients may present with inflammatory involvement of other tissues. Chronic recurrent multifocal osteomyelitis (CRMO) is the most severe form of CNO. We describe the occurrence of Crohn's disease (CD) in four patients, previously diagnosed with CRMO. Mutations in CARD15, encoding the NOD2 protein, have recently been found in patients with CD. Based on the occurence of CNO and CD in these four and several reported patients, we hypothesized that CD and CRMO might share a common autoinflammatory process. Thus, we searched for CD associated CARD15 gene variants R702W, G908R and 1007fs in 29 CNO patients, 4 of them additionally diagnosed with CD. In the latter one out of the four showed compound heterozygosity for the gene variants R702W and 1007fs. The allele frequency in the 25 patients diagnosed with CNO but not CD was not different from that already reported in healthy people (R702W 4.0%, G908R 2.0%, 1007fs 2.0%). The occurrence of non-bacterial bone inflammation and granulomatous intestinal inflammation seems to represent an extended phenotype of CD, which partly might be explained by potential disease causing mutations in CARD15. However, CNO without intestinal inflammation is not associated with common CARD15 gene variants. Therefore, other variants of genes coding for proteins involved in innate immunity and inflammation might predispose for the occurrence of CNO.