Analysis of transcription factor OCT.1, OCT.2 and BOB.1 expression using tissue arrays in classical Hodgkin's lymphoma

Composite Histiocytic Sarcoma and Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma of the Ocular Adnexa

Histiocytic sarcoma (HS) is a rare and aggressive hematologic neoplasm characterized by the proliferation of malignant histiocytes. It infrequently presents with periorbital involvement. Here we present the first documented case of ocular adnexal histiocytic sarcoma composite with chronic lymphocytic leukemia/small lymphocytic lymphoma and provide compelling evidence for the transdifferentiation of chronic lymphocytic leukemia/small lymphocytic lymphoma to histiocytic sarcoma in an 80-year-old woman. Comprehending the clinicopathological characteristics of histiocytic sarcoma and various other histiocytic proliferations and neoplasms affecting orbital and ocular structures is imperative for ophthalmic surgeons and pathologists.

Three-gene signature revealing the dynamics of lymphocyte infiltration in subchondral bone during osteoarthritis progression

Osteoarthritis (OA), a degenerative joint disorder, has an unclear immune infiltration mechanism in subchondral bone (SCB). Thus, this study aims to discern immune infiltration variations in SCB between early- and late-stages of OA and identify pertinent biomarkers. Utilizing the GSE515188 bulk-seq profile from the Gene Expression Omnibus database, we performed single-sample gene-set enrichment analysis alongside weighted gene co-expression network analysis to identify key cells and immune-related genes (IRGs) involved in SCB at both stages. At the meanwhile, differentially expressed genes (DEGs) were identified in the same dataset and intersected with IRGs to find IR-DEGs. Protein-protein interaction network and enrichment analyses and further gene filtering using LASSO regression led to the discovery of potential biomarkers, which were then validated by ROC curve analysis, single-cell RNA sequencing, qRT-PCR, western blot and immunofluorescence. ScRNA-seq analysis using GSE196678, qRT-PCR, western blot and immunofluorescence results confirmed the upregulation of their expression levels in early-stage OA SCB samples. Our comprehensive analysis revealed lymphocytes infiltration as a major feature in early OA SCB. A total of 13 IR-DEGs were identified, showing significant enrichment in T- or B-cell activation pathways. Three of them (CD247, POU2AF1, and TNFRSF13B) were selected via the LASSO regression analysis, and results from the ROC curve analyses indicated the diagnostic efficacy of these 3 genes as biomarkers. These findings may aid in investigating the mechanisms of SCB immune infiltration in OA, stratifying OA progression, and identifying relevant therapeutic targets.

CAR-T Cell Therapy for Classical Hodgkin Lymphoma

Classical Hodgkin lymphoma (cHL) is a malignancy characterized by the presence of Hodgkin and Reed-Sternberg (HRS) cells within a complex tumor microenvironment (TME). Despite advances in conventional therapies, a subset of cHL patients experience relapse or refractory disease, necessitating the exploration of novel treatment strategies. Chimeric antigen receptor T cell (CAR-T cell) therapy has emerged as a promising approach for the management of cHL, harnessing the power of genetically modified T cells to recognize and eliminate tumor cells. In this article, we provide an overview of the pathogenesis of cHL, highlighting the key molecular and cellular mechanisms involved. Additionally, we discuss the rationale for the development of CAR-T cell therapy in cHL, focusing on the identification of suitable targets on HRS cells (such as CD30, CD123, LMP1, and LMP2A), clonotypic lymphoma initiating B cells (CD19, CD20), and cells within the TME (CD123, CD19, CD20) for CAR-T cell design. Furthermore, we explore various strategies employed to enhance the efficacy and safety of CAR-T cell therapies in the treatment of cHL. Finally, we present an overview of the results obtained from clinical trials evaluating the efficacy of CAR-T cell therapies in cHL, highlighting their potential as a promising therapeutic option. Collectively, this article provides a comprehensive review of the current understanding of cHL pathogenesis and the rationale for CAR-T cell therapy development, offering insights into the future directions of this rapidly evolving field.

Differentiating fulminant EBV infection complicated by HLH from Lymphoma: report of a case and a brief literature review

Epstein-Barr virus (EBV) infection may present with fulminant constitutional symptoms, cytopenia(s), and systemic lymphadenopathy, raising clinical suspicion for lymphoma and prompting lymph node and bone marrow biopsies. At the microscopic level, the histopathologic findings in cases of acute EBV lymphadenitis may mimic certain lymphoid neoplasms, creating a range of differential diagnoses and diagnostic pitfalls.We present a case of fulminant EBV infection in an adolescent whose clinical and radiographic findings led to lymph node and bone marrow biopsies to rule out lymphoma. One week after being diagnosed with acute EBV infection (infectious mononucleosis), a 17-year-old Caucasian male presented with worsening symptoms including persistent fever, progressive, painful lymphadenopathy, and splenomegaly. A peripheral blood smear showed lymphocytosis with many reactive lymphocytes, anemia, and thrombocytopenia. Laboratory studies showed elevated ferritin, triglycerides, and soluble IL-2/CD25. A cervical lymph node biopsy demonstrated an EBV-positive, reactive B-immunoblast proliferation with large atypical lymphoid cells mimicking Reed-Sternberg cells of Hodgkin lymphoma, in addition to patchy vasculitis, coagulative necrosis, and prominent hemophagocytic activity. Bilateral bone marrow biopsies showed a hypercellular marrow with patchy infiltrates of similar EBV-positive, large atypical lymphoid cells, as well as prominent hemophagocytic activity. The diagnosis of acute EBV associated lymphoproliferation with concurrent hemophagocytic lymphohistiocytosis (HLH) was rendered.Recognition of common and uncommon clinical presentations of acute EBV infection is essential, particularly when histopathologic findings raise suspicion for a possible hematolymphoid neoplasm. Both the lymph node architectural and viral cytopathic changes observed in EBV lymphadenitis exhibit significant morphologic overlap with classic Hodgkin lymphoma (cHL) and several other lymphomas, including anaplastic large cell lymphoma, diffuse large B cell lymphoma, and angioimmunoblastic T cell lymphoma. Recognition of immunohistochemical staining patterns in EBV lymphadenitis is critical to avoid misdiagnosis. Conversely, bona fide lymphoma, particularly cHL, can masquerade as EBV infection. We provide a concise discussion and tables of the histopathologic differential diagnosis of EBV lymphadenitis, including cHL and other lymphomas. Pathologists should include acute EBV infection within the differential diagnosis when confronted with clinical and pathologic findings concerning for lymphoma, particularly in adolescents and young adults.

Immunohistochemical Expression of B Cell Transcription Factors in Hodgkin’s Lymphoma and Their Use in Differential Diagnosis

Aim: Classical Hodgkin lymphoma is common, it is one of the lymphomas whose differential diagnosis can be difficult. It is thought that Hodgkin cell may originate from the germinal center. Our aim in this study was to determine the germinal center transformation markers OCT-2, BOB.1, BCL-6, PAX-5, CD20 and MUM-1 in Classic Hodgkin Lymphoma (CHL), Nodular Lymphocyte Predominant Hodgkin Lymphoma (NLPHL) and Diffuse Large B-cell Lymphoma (DLBCL) to evaluate the expressions of by immunohistochemical method and chromogenic in-situ hybridization (ISH) of EBV early RNAs (EBER). Material and methods: 49 biopsies diagnosed with Hodgkin lymphoma (HL), 5 with NLPHL and 19 with DLBCL were evaluated for CD30, PAX-5, OCT-2, BOB.1, MUM-1, BCL-6, and CD20, and EBER positivity. SPSS 18 was used for statistical analysis. Results: 73 lymphoma cases were included in the study, 61.6% males and 38.4% females. The median age of patients was 50 years. CHL (67.1%) was the most common lymphoma type, and mixed cellular Hodgkin lymphoma (MSHL) was the most common subtype. There was a statistically significant difference in CD30, OCT-2, BOB.1, MUM-1, PAX-5, CD20, BCL-6, EBER expression between CHL and DLBCL cases (p

Immunohistochemical expression of transcription factors PAX5, OCT2, BCL6 and transcription regulator P53 in Non-Hodgkin lymphomas: A diagnostic cross-sectional study

Background

Non-Hodgkin lymphoma represents a heterogeneous group of tumors that constitute the seventh most common malignancy. Immunohistochemistry plays a major role in the detection of specific cell receptors. Transcription factors are a heterogeneous group of genes that play a critical role in the commitment, differentiation, and proliferation of specific cell types.

Methods

Paraffin-embedded tissue sections of non-Hodgkin lymphoma cases were selected, classified, and evaluated before staining with immunohistochemical markers (PAX5, OCT2, BCL6, and P53). Expression of the aforementioned markers was compared with histological subtypes and grades of lymphoma cases. Means of expression were also compared among histological subtypes.

Results

A total of 55 cases of NHL including 26 cases of low-grade lymphomas and 29 cases of high-grade lymphomas were included in the study. DLBCL and FL were the most common subtypes of high-grade and low-grade lymphomas respectively. Both PAX5 and OCT2 were positive in 44 cases of NHL (80%) including all cases of B-cell lymphomas. BCL6 and P53 demonstrated positive expression in 29.1% and 67.3% respectively. Interestingly, we found a significant association between the histological subtypes and the aforementioned markers (P-value<0.05).

Discussion

Expression of PAX5, OCT2, BCL, and P53 played a major role in the diagnosis and grading of non-Hodgkin lymphomas in our study. Both PAX5 and OCT2 provided more accuracy and specificity in the diagnosis of B-cell neoplasms compared to the classical B-cell markers. BCL6 expression reflected its role in germinal center formation in normal and malignant lymphoid tissues, and expression of P53 mirrored the accumulation of gene mutations in more aggressive lymphoma subtypes.

Conclusion

In this manuscript, we aimed to present a unique study that highlights the immunohistochemical expression of all the aforementioned factors among various histological subtypes of non-Hodgkin lymphomas with disparities in histological aggressiveness, highlighting a promising diagnostic and prognostic panel for non-Hodgkin lymphomas.

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Transcription factors are essential for the differentiation of B-cells.

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PAX5 and OCT2 provide more accuracy in the diagnosis of lymphomas.

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BCL6 expression reflects its role in germinal center formation.

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P53 expression is higher in aggressive subtypes.

5-Azacytidine Suppresses the Expression of Tissue-Specific Oct-1 Isoform in Namalwa Burkitt's Lymphoma Cell Culture

Overexpression of the transcription factor POU2F1 (Oct-1) increases the malignant potential of the tumor and determines the unfavorable prognosis for both solid and hematological cases of the disease in human carcinogenesis. The Oct-1 level determines the rate of development of the disease in acute myelodysplastic leukemia (AML), and a decrease in its expression significantly delays the development of leukemia in mice; however, a complete knockout of Oct-1 leads to the death of the animals. POU2F1 (Oct-1) is expressed as several isoforms transcribed from alternative promoters. They include both ubiquitous and tissue-specific isoforms. It was shown that in Burkitt’s lymphoma Namalwa cells 5-azacytidine specifically suppresses the expression of the tissue-specific isoform Oct-1L mRNA (level of Oct-1L is abnormally increased in these cells), while not causing changes in the amount of the ubiquitous isoform Oct-1A mRNA. These results show that it is possible to selectively reduce the transcription level of the Oct-1L isoform aberrantly expressed in human tumor cells.

POU2F2-IL-31 Autoregulatory Circuit Converts Hepatocytes into the Origin Cells of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) originates from fully differentiated hepatocytes, but the decisive events for converting hepatocytes to the cells of origin for HCC are still unclear. Liver cancer stem cells (LCSCs) cause HCC but are not bona fide cells of origin. Here, the expressions of POU2F2 and IL-31 are identified in macroscopically normal livers of diethylnitrosamine-challenged mice. An autoregulatory circuit formed by mutual induction between POU2F2 and IL-31 drives hepatocytes to progress to LCSCs by acquiring stemness, as well as stimulates them to in vivo grow and malignantly progress. The development of the autoregulatory circuit is a decisive event for converting hepatocytes into the cells of origin, since hepatocytes expressing the circuit have acquired tumorigenic potential before progressing to LCSCs. Nonetheless, acquiring stemness is still required for the cells of origin to initiate hepatocarcinogenesis. The circuit also occurs in human cirrhotic tissues, partially elucidating how premalignant lesions progress to HCC.

Clinicopathological significance of CD79a expression in classic Hodgkin lymphoma

Classic Hodgkin lymphoma (CHL) is a lymphoid neoplasia characterized by the presence of large tumor cells, referred to as Hodgkin and Reed-Sternberg (HRS) cells, originating from B-cells in an inflammatory background. As the clinical significance of B-cell markers has yet to be fully elucidated, this study aimed to clarify the clinicopathological significance of CD79a in 55 patients with CHL. They were immunohistochemically divided into two groups, comprising of 20 CD79a-positive and 35 CD79a-negative patients. There was no significant correlation between CD79a and CD20 expression (rs = 0.125, P = 0.362). CD79a-positive patients were significantly older at onset (P = 0.011). There was no significant correlation between CD79a-positivity and clinical stage (P = 0.203), mediastinal involvement (P = 0.399), extranodal involvement (P = 0.749), or laboratory findings, including serum levels of lactate dehydrogenase (P = 1) and soluble interleukin-2 receptor (P = 0.251). There were significant differences in overall survival (OS) (P = 0.005) and progression-free survival (PFS) (P = 0.007) between CD79a-positive and CD79a-negative patients (5-year OS: 64.6% and 90.5%; 5-year PFS: 44.0% and 76.6%, respectively). Five patients in whom the majority (> 80%) of HRS cells expressed CD79a consisted of 4 males and 1 female aged between 52 and 81 years; 4 of them were in a limited clinical stage. We concluded that CD79a-positive CHL may have unique clinicopathological features.

Overexpressing of POU2F2 accelerates fracture healing via regulating HMGA1/Wnt/β-catenin signaling pathway

To elucidate the role of POU2F2 (POU class 2 homeobox 2) in fracture healing, 30 rats with femoral fracture were randomly grouped into three groups: FF group, LV-POU2F2 group and LV-scramble group. Rats were injected with PBS, lentivirus expressing POU2F2 or scramble lentivirus once a week for 4 weeks. Results showed that overexpressing of POU2F2 promoted fracture healing and callus growth. Besides, overexpressing of POU2F2 promoted protein and mRNA expression of Col10a1, Runx2, Osterix, and Osteocalcin. High Mobility Group AT-hook 1 (HMGA1) is a non-histone protein participating in chromatin remodeling of cells. Western blotting manifested HMGA1/Wnt/β-catenin pathway was activated in POU2F2 group. Moreover, in-vitro study of hMSCs cells supported the above data. In conclusion, POU2F2 promotes fracture healing via activating the HMGA1/Wnt/β-catenin signaling pathway.

J chain and myocyte enhancer factor 2B are useful in differentiating classical Hodgkin lymphoma from nodular lymphocyte predominant Hodgkin lymphoma and primary mediastinal large B-cell lymphoma

Although most classical Hodgkin lymphomas (CHLs) are easily distinguished from nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) and primary mediastinal large B-cell lymphoma (PMBL), cases with significant CD20 expression cause diagnostic confusion. Although the absence of OCT-2 and BOB.1 are useful in these circumstances, a variable proportion of CHLs are positive for these antigens. We investigated the utility of J chain and myocyte enhancer factor 2B (MEF2B) in the diagnosis of CHL; NLPHL; PMBL; T-cell/histiocyte-rich large B-cell lymphoma (TCRLBL); and B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and CHL, compared with OCT-2 and BOB.1. J chain and MEF2B highlighted lymphocyte predominant (LP) cells in 20/20 (100%) NLPHLs and were negative in 43/43 (100%) CHLs. Fourteen of 15 (93%) PMBLs and 4/4 (100%) TCRLBLs were MEF2B positive, whereas 67% of PMBLs and 50% of TCRLBLs were J chain positive. Three of 3 B-cell lymphomas, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and CHL, were negative for J chain and MEF2B. J chain and MEF2B were 100% sensitive and specific for NLPHL versus CHL. MEF2B was 100% sensitive and 98% specific for PMBL versus CHL. Whereas loss of OCT-2 and/or BOB.1 expression had a sensitivity of only 86% and specificity of 100% for CHL versus NLPHL, PMBL, and TCRLBL, lack of both J chain and MEF2B expression was 100% sensitive and 97% specific. J chain and MEF2B are highly sensitive and specific markers of NLPHL versus CHL; are particularly useful in highlighting LP cells; and, with rare exception, are of greater utility than OCT-2 and BOB.1 in differentiating CHL from NLPHL and other large B-cell lymphomas.

T cell-rich lymphoid infiltrates with large B cells: a review of key entities and diagnostic approach

Accurate diagnostic interpretation of a lymphoid population composed predominantly of small T cells, together with smaller numbers of large B cells, with or without a nodular architecture, is a common problem faced by the histopathologist. The differential diagnosis of this histological pattern is wide, ranging from reactive conditions such as drug reactions and viral infections, through borderline entities such as immunodeficiency-related lymphoproliferative disorders to lymphomas. The latter includes entities where the large B cells are primarily neoplastic (classical and nodular lymphocyte-predominant Hodgkin lymphomas and T cell/histiocyte-rich large B cell lymphoma) as well as T cell lymphomas such as angioimmunoblastic T cell lymphoma where the large B cells represent an epiphenomenon and may or may not be neoplastic. Several rare variants of these conditions, and the fact that treatment can significantly modify appearances, add to the diagnostic difficulty of these pathological entities. Unlike monomorphic lymphoid infiltrates, the histological pattern of T cell-rich proliferation with large B cells requires close evaluation of the inter-relationship between B cells and T cells, follicular dendritic cells and sometimes other inflammatory cells. Epstein-Barr virus plays a key role in several of these scenarios, and interpreting not only its presence but also its distribution within cellular subgroups is essential to accurate diagnosis and the avoidance of some important diagnostic pitfalls. An understanding of normal immunoarchitecture and lymphoid maturational pathways is also fundamental to resolving these cases, as is a knowledge of their common patterns of spread, which facilitates correlation with clinical and radiological findings.

POU2F2-oriented network promotes human gastric cancer metastasis

BACKGROUND AND AIMS

Aberrant upregulation of POU2F2 expression has been discovered in metastatic gastric cancer (GC). However, the mechanisms underlying the aberrant upregulation and the potential functions of POU2F2 remain uncertain.

DESIGN

The role and mechanism of POU2F2 in GC metastasis were investigated in gastric epithelial cells, GC cell lines and an experimental metastasis animal model by gain of function and loss of function. Upstream and downstream targets of POU2F2 were selected by bioinformatics and identified by luciferase reporter assay, electrophoretic mobility shift assay and chromatin immunoprecipitation PCR. The influence of miR-218 on its putative target genes (POU2F2, ROBO1 and IKK-β) and GC metastasis was further explored via in vitro and in vivo approaches.

RESULTS

Increased POU2F2 expression was detected in metastatic GC cell lines and patient samples. POU2F2 was induced by the activation of nuclear factor (NF)-κB and, in turn, regulated ROBO1 transcription, thus functionally contributing to GC metastasis. Finally, miR-218 was found to suppress GC metastasis by simultaneously mediating multiple molecules in the POU2F2-oriented network.

CONCLUSIONS

This study demonstrated that NF-κB and the SLIT2/ROBO1 interaction network with POU2F2 as the central part may exert critical effects on tumour metastasis. Blocking the activation of the POU2F2-oriented metastasis network using miR-218 precursors exemplified a promising approach that sheds light on new strategies for GC treatment.

The Oct1 transcription factor and epithelial malignancies: Old protein learns new tricks

The metazoan-specific POU domain transcription factor family comprises activities underpinning developmental processes such as embryonic pluripotency and neuronal specification. Some POU family proteins efficiently bind an 8-bp DNA element known as the octamer motif. These proteins are known as Oct transcription factors. Oct1/POU2F1 is the only widely expressed POU factor. Unlike other POU factors it controls no specific developmental or organ system. Oct1 was originally described to operate at target genes associated with proliferation and immune modulation, but more recent results additionally identify targets associated with oxidative and cytotoxic stress resistance, metabolic regulation, stem cell function and other unexpected processes. Oct1 is pro-oncogenic in multiple contexts, and several recent reports provide broad evidence that Oct1 has prognostic and therapeutic value in multiple epithelial tumor settings. This review focuses on established and emerging roles of Oct1 in epithelial tumors, with an emphasis on mechanisms of transcription regulation by Oct1 that may underpin these findings. This article is part of a Special Issue entitled: The Oct Transcription Factor Family, edited by Dr. Dean Tantin.

Peak-valley-peak pattern of histone modifications delineates active regulatory elements and their directionality

Formation of nucleosome free region (NFR) accompanied by specific histone modifications at flanking nucleosomes is an important prerequisite for enhancer and promoter activity. Due to this process, active regulatory elements often exhibit a distinct shape of histone signal in the form of a peak-valley-peak (PVP) pattern. However, different features of PVP patterns and their robustness in predicting active regulatory elements have never been systematically analyzed. Here, we present PARE, a novel computational method that systematically analyzes the H3K4me1 or H3K4me3 PVP patterns to predict NFRs. We show that NFRs predicted by H3K4me1 and me3 patterns are associated with active enhancers and promoters, respectively. Furthermore, asymmetry in the height of peaks flanking the central valley can predict the directionality of stable transcription at promoters. Using PARE on ChIP-seq histone modifications from four ENCODE cell lines and four hematopoietic differentiation stages, we identified several enhancers whose regulatory activity is stage specific and correlates positively with the expression of proximal genes in a particular stage. In conclusion, our results demonstrate that PVP patterns delineate both the histone modification landscape and the transcriptional activities governed by active enhancers and promoters, and therefore can be used for their prediction. PARE is freely available at http://servers.binf.ku.dk/pare.

Mediastinal Gray Zone Lymphoma

Aim. To identify aggressively behaving classical Hodgkin lymphoma (CHL) of mediastinum and primary mediastinal B-cell lymphoma (PMBCL) and to classify them as mediastinal gray zone lymphoma(MGZL) and to define a minimum immunopanel for the diagnosis of MGZL. Materials and Methods. Ninety-two mediastinal B-cell lymphomas were reviewed with a wide immunopanel and were classified as CHL, PMBCL, or MGZL. CHL with an expression of 3 or 4 transcription factors performed worse, and hence the CHL with ≥3 transcription factors were classified as MGZL-CHL. In PMBCL, the cases with a weak or negative CD20 and positive CD15 as well as those cases showing cyclin E positivity with a negative or focal LCA and any one of the transcription factors were classified as MGZL-PMBCL. Results. The MGZL cases expanded from 9 to 28 cases after using an extended immunopanel. CHL and PMBCL had a disease-free survival rate of 86.8% and 69.2% and an overall survival rate of 97.4% and 80.8%, respectively. MGZL-CHL and MGZL-PMBCL had a disease-free survival rate of 33% and 40% and an overall survival rate of 66.7% and 60%, respectively. Conclusion. Thus, the MGZL may be a wider category than we think and hence the use of a wide immunopanel is recommended to identify the aggressively behaving mediastinal B-cell lymphomas.

Atypical Phenotypes in Classical Hodgkin Lymphoma

Classical Hodgkin lymphoma has a characteristic immunophenotype in most cases, with expression of CD30, CD15, and PAX-5, and absence of CD45 and T-lineage markers. However, in a significant subset of cases, atypical staining patterns may be seen for one or more antigens, particularly negative staining for CD15 or staining for one or more B-lineage markers, such as CD20, CD79a, OCT-2, or BOB.1. The greatest pitfall is in the misinterpretation of other cells, such as immunoblasts or histiocytes, as Hodgkin cells.

Reed-Sternberg–Like Cells in Non-Hodgkin Lymphomas

Large atypical cells with morphologic and immunophenotypic features resembling Reed-Sternberg cells can be seen in the background of reactive lymphadenopathies as well as non-Hodgkin lymphomas. The presence of these cells is an important diagnostic pitfall that must be recognized by pathologists who regularly interpret lymph node biopsies. A thorough evaluation of the morphologic and immunophenotypic features of these cells and the cellular milieu is crucial in achieving the correct diagnosis. In this review, examples of lymphomas presenting with Reed-Sternberg–like cells will be provided. Additionally, a detailed description of the common morphologic and immunophenotypic features of these cells, as well as strategies that can be used to distinguish them from the Reed-Sternberg cells of classical Hodgkin lymphoma, will be emphasized.

CD20 Over-Expression in Hodgkin-Reed-Sternberg Cells of Classical Hodgkin Lymphoma: the Neglected Quest

We have scrutinized a previously analyzed cohort of classical Hodgkin lymphoma patients for evidence of a CD20 over-expression. This was pursued in order to determine whether all the 24 (12.6%) CD20+++ patients had clinical and/or biological profiles which would warrant a separate consideration and treatment or would carry a different outcome from our 166 CD20 (-) classical Hodgkin lymphoma patients. Except for an older age and a significantly lower expression of non-sialyl-CD15 antigen, both previously described in classical Hodgkin lymphoma, no justification to exclude these CD20+++ patients from the cohort at large is apparent. We suggest that the generally accepted view to the contrary be revised. In addition, we propose alternative interpretations for the low expression of CD20 found in a majority of Hodgkin-Reed-Sternberg cells in classical Hodgkin lymphoma.

Lymphocyte-Rich Classical Hodgkin Lymphoma. A Case with Difficulty in Distinguishing from Nodular Lymphocyte-Predominant Hodgkin Lymphoma

A 35-year-old man was referred to our hospital because of left supraclavicular and cervical lymphadenopathies. Histopathological examination of the lymph nodes revealed reactive lymphadenopathy. He visited our hospital three years after the initial diagnosis because of enlarged left cervical lymph nodes. Histopathologically, both Hodgkin/Reed-Sternberg (H/RS) and lymphocyte-predominant (LP) cells were found in the lymph node. We first suspected nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL), because these cells were CD15(-) and CD30(-). However, the diagnosis of lymphocyte-rich classical Hodgkin lymphoma (LRCHL) was finally confirmed, because these cells were found to be CD20(-), Bob.1(+), Oct.2(-), and BCL6(-) by additional immunostaining. The patient was treated with six cycles of ABVD chemotherapy, and a complete response was achieved. However, he underwent autologous stem-cell transplantation after high-dose chemotherapy owing to a relapse 10 months after primary treatment. Distingushing LRCHL from NLPHL was difficult in this patient, because histopathological examination showed both H/RS and LP cells, and immunostaining revealed these cells to be triple negative (CD15(-), CD30(-) and CD20(-)). Accumulation of such cases are necessary to establish better criteria for the differential diagnosis and assessment of clinical behavior.

The role of Pax5 in leukemia: diagnosis and prognosis significance

Pax5 transcription factor, also known as B-cell specific activator protein (BSAP), plays a dual role in the hematopoietic system. Pax5 expression is essential in B-cell precursors for normal differentiation and maturation of B-cells. On the other hand, it inhibits the differentiation and progress toward other lineages. The expression of this factor is involved in several aspects of B-cell differentiation, including commitment, immunoglobulin gene rearrangement, BCR signal transduction and B-cell survival, so that the deletion or inactivating mutations of Pax5 cause cell arrest in Pro-B-cell stage. In recent years, point mutations, deletions and various rearrangements in Pax5 gene have been reported in several types of human cancers. However, no clear relationship has been found between these aberrations and disease prognosis. Specific expression of Pax5 in B-cells can raise it as a marker for the diagnosis and differentiation of B-cell leukemias and lymphomas as well as account for remission or relapse. Extensive studies on Pax5 along with other genes and immunomarkers are necessary for decisive results in this regard.

A single slide multiplex assay for the evaluation of classical Hodgkin lymphoma

Classical Hodgkin lymphoma can be diagnosed with confidence in the majority of cases, but there is a significant subset that remains a diagnostic challenge. The authors have investigated the utility of a novel hyperplexing technology, MultiOmyx™, which may be applied to stain with >60 antibodies on single tissue sections from formalin-fixed paraffin-embedded tissue as an aid to the diagnosis of classical Hodgkin lymphoma. The multiplexing protocol included CD30, CD15, PAX-5, CD20, CD79a, CD45, BOB.1, OCT-2, and CD3 antibodies. The technology showed a high degree of sensitivity, specificity, and precision. Comparison studies with routine hematoxylin and eosin and immunohistochemical assessment of hematopathology cases in which classical Hodgkin lymphoma was included in the differential diagnosis showed concordance in 54 of 56 cases, with the 2 discordant cases illustrating the potential of this multiplexed immunofluorescence technology to improve on traditional immunohistochemistry for classical Hodgkin lymphoma diagnosis. This technology is practical for routine diagnosis and may be particularly useful in cases in which the sample size is limited, few Hodgkin-like cells are present, or in CD30-positive lymphoma cases with difficult morphology. MultiOmyx may potentially benefit other areas of research and diagnostic pathology.

BOB.1-positive Classical Hodgkin's Lymphoma Carries Hypermethylation of Its Promoter as Epigenetic Marker of Gene-silencing Memory

Analysis of archival formalin-fixed, paraffin-embedded (FFPE) pathological specimens of three case of Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) and three cases of classical Hodgkin lymphoma (CHL) revealed that hypermethylation of the BOB.1 gene promoter was exclusively observed in CHL. A discrepancy was observed, however, between the methylation status of the BOB.1 gene promoter and its expression in the EBV-positive mixed cellular CHL (MCCHL). Since MCCHL lacks the typical B-cell phenotype even in the presence of abundant BOB.1 transcription factors, functional activity of BOB.1 may be lost or reduced by a mechanism other than epigenetic gene silencing. When some tumor-suppressor gene products have lost their biological function, impact or significance of derepression of such genes may be little. Therefore, when interpreting immunohistochemical results for diagnostic or research purposes, it must be borne in mind that apparent positive immunostaining can merely be the result of chromatin remodeling and that such transient expression often has little functional significance. Any apparent positive immunohistochemical result needs to be interpreted carefully with the help of the hypermethylation status as a molecular marker of gene silencing memory.

Aberrant T-cell antigen expression in classical Hodgkin lymphoma is associated with decreased event-free survival and overall survival

Hodgkin/Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL) rarely express T-cell-associated antigens (TCA), but the clinical significance of this finding is uncertain. Fifty cHLs expressing any TCA on the HRS cells (TCA-cHL) were identified in two cohorts (National Cancer Institute, n = 38; Basel, n = 12). Diagnostic pathology data were examined in all cases with additional T-cell receptor γ rearrangements (TRG@) polymerase chain reaction (PCR) in a subset of cases. The outcome data were compared with a cohort of cHLs negative for TCA (n = 272). Primary end points examined were event-free survival (EFS) and overall survival (OS). The median age in the TCA-cHL group was 40 years (range, 10-85 years). Seventy percent presented in low stage (stage I/II) at presentation with nodular sclerosis (NS) histology predominating in 80% of cases. Among the TCA, CD4 and CD2 were most commonly expressed, seen in 80.4% and 77.4% of cases, respectively. TRG@ PCR was negative for clonal rearrangements in 29 of 31 cases. During a median follow up of 113 months, TCA expression predicted shorter OS (adjusted hazard ratio [HRadj] = 3.32 [95% confidence interval (CI): 1.61, 6.84]; P = .001) and EFS (HRadj = 2.55 [95% CI: 1.45, 4.49]; P = .001). TCA-cHL often display NS histology, lack T-cell genotype, and are independently associated with significantly shorter OS and EFS compared with TCA-negative cHLs.

Prognostic impact of MUM1 expression by immunohistochemistry on primary mediastinal large B-cell lymphoma

Diffuse large B-cell lymphoma can be classified into two prognostically distinct subgroups with germinal center B-cell-like (CG) and activated B-cell-like (post-CG) characteristics, based on CD10, BCL-6, and MUM1 expression. We performed a retrospective analysis of the clinical variables of 37 patients with primary mediastinal large B-cell lymphoma and the expression of BCL-6 and MUM1 in 22 patients with available tissue. The median age was 30 years, and 70% of the patients were female. BCL-6 and MUM1 were expressed in 64% and 45% of cases, respectively. Five-year overall survival (OS) and disease-free survival (DFS) were 47% and 81%, respectively. In univariate analysis, complete response (p = 0.0001), radiation therapy (p = 0.01), International Prognostic Index (p = 0.001), and MUM1 expression (p = 0.002) correlated with OS. For this group of patients with homogeneous clinical characteristics, response to initial chemotherapy and MUM1 expression were associated with prognosis.

Expression of heat shock proteins in classical Hodgkin lymphoma: correlation with apoptotic pathways and prognostic significance

AIMS

Heat shock proteins (HSPs), known to inhibit apoptosis and promote cellular survival, are overexpressed in many tumours. We analysed the expression of relevant HSPs and heat shock factor 1 (HSF1) in classical Hodgkin lymphoma (cHL) and their relationship with caspase signalling pathways and patient outcome.

METHODS AND RESULTS

Using tissue microarrays (TMAs), most cases showed strong immunohistochemical expression of HSPs [10, 27, 40, 60, 70, 90, 110, HO1, cell division cycle 37 homolog (CDC37) and HSF1, which points to cHL as a potential candidate to stress-response inhibitors. Active caspases 3, 8 and 9 were detected in 55.1%, 55.4% and 96.2% of cases although cleaved poly (ADP-ribose) polymerase (PARP) was observed in only 16.1%, suggesting an improper functioning of apoptosis. Statistical analysis showed associations of HSP70 with active caspase 3 (P = 0.000); HSP40 with active caspase 9 (P = 0.031) and p53 (P = 0.003); HO1 with p53 (P = 0.006) and p21 (P = 0.005); and p53 with p21 (P = 0.015).

CONCLUSIONS

Correlations between the expression of apoptotic markers and HSPs may suggest a role for the latter in modulating apoptosis in cHL, mainly through the HSP70-HSP40 system, and in the stabilization of p53. Survival analyses showed that absence of active caspase 8 and HO1 had a negative impact in patient outcome.

BOB.1, CD79a and cyclin E are the most appropriate markers to discriminate classical Hodgkin's lymphoma from primary mediastinal large B-cell lymphoma

AIMS

To clarify which immunohistochemical markers could be helpful in distinguishing between classical Hodgkin's lymphoma (cHL) and primary mediastinal B-cell lymphoma (PMBCL) to more narrowly define 'B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and cHL'.

METHODS AND RESULTS

Two hundred and 83 cHLs and 51 PMBCLs were analysed on validated tissue microarray platforms with antibodies to BOB.1, CD15, CD20, CD23, CD30, CD79a, cyclin E, LMP-1, MUM1p, p63 and Oct2. The marker cut-off scores were calculated using receiver-operating characteristic curves. Markers with the highest positive predictive value for cHL were: CD15, cyclin E, LMP-1 (all 100%), MUM1p (93%) and CD30 (83%). High sensitivity was achieved only by CD30 (92%) and cyclin E (79%). Nineteen percent of PMBCLs were also positive for CD30, which led to a lower specificity of CD30 as regards cHL (81%) compared with cyclin E (100%). The antibodies with the highest positive predictive value for PMBCL were: CD23 (98%), p63 (96%), BOB.1 (94%) and CD79a (90%), with high sensitivity for BOB.1 (100%), CD79a (89%) and p63 (82%).

CONCLUSIONS

The use of at least three of the most accurate immunohistochemical markers, cyclin E, CD79a and BOB.1, may be helpful in the differential diagnosis of cHL and PMBCL.

Utility of fascin and JunB in distinguishing nodular lymphocyte predominant from classical lymphocyte-rich Hodgkin lymphoma

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) and lymphocyte-rich classical Hodgkin lymphoma (LRCHL), although clinically and morphologically similar, differ biologically and in prognosis. Immunolabeling of Reed-Sternberg (RS) cells in LRCHL and lymphocytic and/or histiocytic variants (L&H cells) in NLPHL is often required to help distinguish between the 2 variants. Our aim was to evaluate fascin (a distinct 55-kd actin-bundling protein) and JunB (an activator protein-1 family transcription factor) to differentiate NLPHL from LRCHL. A total of 35 archival cases of NLPHL (n = 24) and LRCHL (n = 11) from adults and children were studied. Slides were reviewed for all cases and clinical, morphologic, and immunohistochemical features were evaluated. Each case was immunostained for fascin and JunB, and immunoreactivity of RS cells, L&H cells, and background lymphocytes were recorded. Whereas occasional L&H cells were weakly positive for fascin in 3 out of 24 (12.5%) cases of NLPHL, RS cells in LRCHL were positive for fascin in 11 out of 11 (100%) cases with a strong cytoplasmic staining pattern. JunB was positive in 10 out of 24 (41.7%) of NLPHL cases, and 11 out of 11 (100%) of LRCHL cases, showing a stippled and/or diffuse nuclear staining pattern. In addition to L & H Cells, JunB also stained small background lymphocytes, particularly in areas of progressively transformed germinal centers of NLPHL. Either stains when tested alone, if negative, or with rare L&H cell weak positivity for fascin, is indicative of NLPHL. The L&H cells of NLPHL cases were negative for concomitant staining in 24 out of 24 (100%) cases. Concomitant positive staining of classic RS cells for fascin and JunB was found in 11 out of 11 (100%) of LRCHL cases. Although fascin positivity alone supports the diagnosis of LRCHL, concomitant positivity offers stronger support and is less likely to lead to a false conclusion if aberrant fascin staining were to be encountered in a case of NLPHL. Staining for fascin and JunB provides a basis for distinguishing NLPHL from LRCHL and offers an alternative to other antibody profiles.

EBV positive mucocutaneous ulcer--a study of 26 cases associated with various sources of immunosuppression

We describe a series of Epstein Barr virus (EBV)-positive circumscribed, ulcerative lesions associated with various types of immunosuppression (IS). The study group (26 patients) comprised 10 males and 16 females, median age 77 years (range 42 to 101). IS in 9 cases included azathioprine (AZA), methotrexate (MTX) or cyclosporin-A (CyA). Seventeen patients had age-related immunosenescence. Patients presented with isolated sharply circumscribed ulcers involving oropharyngeal mucosa (16), skin (6), and gastrointestinal tract (4). Lesions were histologically characterized by a polymorphous infiltrate and atypical large B-cell blasts often with Hodgkin/Reed-Sternberg (HRS) cell-like morphology. The B cells showed strong CD30 and EBER positivity, some with reduced CD20 expression, in a background of abundant T cells. CD15 was positive in 43% of cases (10/23). The pathologic features were identical regardless of the anatomic site or cause of IS. Polymerase chain reaction revealed 39% (7/18) clonal Ig gene rearrangements with 38% (6/16) and 31% (5/16) clonal and restricted T-cell patterns, respectively. Twenty-five percent of patients (5/20) received standard chemotherapy and/or radiotherapy. Forty-five percent (9/20) regressed spontaneously with no treatment and 15% (3/20) were characterized by a relapsing and remitting course. All of the iatrogenic lesions (6/6) with available follow-up responded to reduction of IS. All patients achieved complete remission with no disease-associated deaths over a median follow-up period of 22 months (range 3 to 72). We propose EBV-positive mucocutaneous ulcer as a newly recognized clinicopathologic entity with Hodgkin-like features and a self-limited, indolent course, generally responding well to conservative management. Association with various forms of IS implies a common pathogenetic mechanism. The localized nature of the disease may be owing to a minimal and localized lapse in immunosurveillance over EBV.

Clinical, phenotypic and genetic similarities and disparities between post-transplant and classical Hodgkin lymphomas with respect to therapeutic targets

OBJECTIVE

Post-transplant Hodgkin lymphoma (ptHL) is a rare but serious complication. We explored the clinical, phenotypic and genetic similarities and disparities between ptHL and classical Hodgkin lymphoma (cHL) in immunocompetent patients and sought proteins/pathways in ptHL that might have potential as therapeutic targets.

RESEARCH DESIGN AND METHODS

Eight ptHL cases in solid organ recipients (mean patient age 36 years; mean duration between organ transplant and onset of ptHL 80 months) were phenotypically and genotypically analyzed and the results were compared with known phenotypic and molecular characteristics of cHL.

RESULTS

All ptHL expressed CD15, CD30 and LMP-1 of EBV; the B-cell markers BOB-1, Oct2, CD79a and CD20 were more commonly expressed in ptHL versus cHL (100%, 86%, 50% and 38% in ptHL compared to 6%, 14%, 10% and 33% in cHL, respectively); all ptHL expressed phosphoinositide 3-kinase (PI3K) versus 81% of cHL; 2/6 (33%) ptHL displayed gains at 9p24 that were similar to cHL (32%). The JAK2 downstream pSTAT3 slightly predominated in ptHL versus cHL (60% versus 50%). Clonal immunoglobulin gene rearrangements were found in 2/4 cases.

CONCLUSIONS

ptHL and cHL are closely related, but not identical, neoplasms, with the primary differences being the strict association with EBV infection, persistent phenotypic B-cell signature and high expression of PI3K as well as the slightly CD4-depleted but TIA-1/Granzyme B-enriched cellular background composition in ptHL.

Lymphocyte-rich classical Hodgkin's lymphoma: distinctive tumor and microenvironment markers

The existence, diagnostic features, and the biological and clinical relevance of lymphocyte-rich classical Hodgkin's lymphoma remain controversial. A comparative marker analysis of lymphocyte-rich classical Hodgkin's lymphoma, nodular lymphocyte-predominance Hodgkin's lymphoma, and of other subtypes of classical Hodgkin's lymphoma was carried out. Markers were selected focusing on B-cell lineage and transcription program (OCT.1, OCT.2, BOB.1, BCL6, PAX-5, GCET1, KLHL6, and BLIMP1), the NF-kappaB signaling pathway (REL-B, C-REL, TRAF-1, p-50, and MUM-1) and the T-cell microenvironment (CD3, CD57, PD-1, CXCL-13, and CD10, BCL-6, CD23). Lymphocyte-rich classical Hodgkin's lymphoma cases displayed features intermediate between those of classical Hodgkin's lymphoma and nodular lymphocyte-predominance Hodgkin's lymphoma. The expression of B-cell transcription factors such as OCT.1, OCT.2, BOB.1, and BCL6 was more frequent in lymphocyte-rich classical Hodgkin's lymphoma than in classical Hodgkin's lymphoma. A follicular T-cell microenvironment was also identified in 50% of lymphocyte-rich classical Hodgkin's lymphoma cases. NF-kB markers were expressed at frequencies comparable with those observed in classical Hodgkin's lymphoma. The neoplastic cell immunophenotype and microenvironment in lymphocyte-rich classical Hodgkin's lymphoma closely mimic that which are observed in the outer zone of the germinal center, where B-cell blasts with germinal-center markers co-express CD30 and the B-cell transcription program, surrounded by follicular T-cell rosettes. Lymphocyte-rich classical Hodgkin's lymphoma seems to be characterized by a stronger expression of the B-cell transcription program by the neoplastic cells and by a follicular T-cell background, occupying an intermediate position between classical Hodgkin's lymphoma and nodular lymphocyte-predominance Hodgkin's lymphoma.

Pathologic and clinical features of Hodgkin lymphoma--like posttransplant lymphoproliferative disease

Because of its rarity, pathologic and clinical features of Hodgkin lymphoma-like posttransplant lymphoproliferative disorder (HL-like PTLD) are not well understood, and it is unclear whether its biological behavior is more closely related to classical Hodgkin disease or to monomorphic B-cell PTLD. The authors compared 6 cases of HL-like PTLD with 5 cases of monomorphic B-cell PTLD for differences in histology, immunophenotype, and clinical behavior. Histologically, all cases of HL-like PTLD resembled classical HL with typical Reed-Sternberg (RS) cells and a cellular background mimicking mixed cellularity subtype. CD45 was absent on RS-like cells, but the expression pattern of B-cell-associated markers Oct-2 and BOB.1 resembled monomorphic B-cell PTLD. Whereas Epstein-Barr virus early RNA expression is normally restricted to RS cells of classical HL, it was expressed in both RS-like cells and background lymphocytes in HL-like PTLD. Although all patients diagnosed with monomorphic B-cell PTLD show no evidence of disease following treatment, half of the patients with HL-like PTLD relapsed or died, indicating a more aggressive clinical behavior. The findings suggest that HL-like PTLD represents a distinct clinicopathologic entity with an aggressive clinical course.

Hodgkin-like anaplastic large cell lymphoma (previously designated in the REAL classification) has same immunophenotypic features to classical Hodgkin lymphoma

In the WHO classification, the majority of Hodgkin-like ALCL cases as defined by the REAL classification are considered to be CHL. However, establishing a histological diagnosis for the gray zone between CHL and ALCL is often confusing. In this study, we re-evaluated such cases by performing immunohistochemistry with antibodies against PAX-5/BSAP, Oct.2, and BOB.1/OBF.1. Expression of PAX-5/BSAP was observed in 88% (76/87) of CHL specimens and none (0/11) of ALK-positive ALCL specimens. Among specimens of Hodgkin-like ALCL and ALK-negative ALCL, expression of PAX-5/BSAP was observed in 77% (20/26) and 18% (3/17), respectively. Most of the PAX-5/BSAP-positive specimens were negative for Oct.2 and/or BOB.1/OBF.1 except for four CHL specimens. Our results may support the WHO classification in which most cases of Hodgkin-like ALCL are classified as CHL. However, the patients with Hodgkin-like ALCL with CHL-immunophenotype (PAX-5/BSAP-positive and negative for Oct.2 and/or BOB.1) did not have a favorable outcome, with a 5-year OS rate of 58%.

B-cell differentiation immunophenotypes in classical Hodgkin lymphomas

The bcl6/CD10/MUM1/CD138 B-cell differentiation immunophenotypes were analysed in 101 cases of classical Hodgkin lymphomas (cHL) aiming to elucidate their histogenesis. Three major bcl6/CD10/MUM1/CD138 immunophenotypes were distinguished on the basis of the immunohistochemical positivity of Hodgkin and Reed-Sternberg (H/RS) cells: (a) the late germinal center (GC)/early post-GC B-cell-like immunophenotype (bcl6-/CD10-/MUM1+/CD138-); 59/101 cases (59%), (b) the post-GC B-cell-like immunophenotype (bcl6-/CD10-/MUM1+/CD138+); 24/101 cases (24%) and (c) the indeterminate immunophenotype (bcl6+/CD10-/MUM1+/CD138-: 14 cases and bcl6+/CD10-/MUM1+/CD138+: four cases); 18/101 cases (18%). The above findings indicate that H/RS cells in most cHL display bcl6/CD10/MUM1/CD138 immunophenotypes consistent with late GC/early post-GC or post-GC B-cell differentiation. In addition, H/RS cells in a small fraction of cHL display indeterminate bcl6/CD10/MUM1/CD138 immunophenotypic profiles which are characterized by simultaneous expression of GC, late GC/early post-GC and post-GC B-cell differentiation proteins. These immunophenotypic profiles do not correspond to the differentiation immunophenotypes of normal B-cells and their identification in a part of cHL suggests that the differentiation process of H/RS cells is not complete in a fraction of these cells and/or is still ongoing at the time of observation.

How will haematologists use proteomics?

Proteomics technologies are emerging as a useful tool in the identification of disease biomarkers, and in defining and characterising both normal physiological and disease processes. Many cellular changes in protein expression in response to an external stimulus or mutation can only be characterised at the proteome level. In these cases protein expression is often controlled by altered rates of translation and/or degradation, making proteomics an important tool in the analysis of biological systems. In the leukaemias, post-translational modification of proteins (e.g. phosphorylation, acetylation) plays a key role in the molecular pathology of the disease: such modifications can now be detected with novel proteomic methods. In a clinical setting, serum remains a relatively un-mined source of information for prognosis and response to therapy. This protein rich fluid represents an opportunity for proteomics research to benefit hematologists and others. In this review, we discuss the technologies available for the study of the proteome that offer realistic opportunities in haematology.

Primary gastric Hodgkin's lymphoma expressing a B-Cell profile including Oct-2 and Bob-1 proteins

Classic Hodgkin's lymphoma (cHL) most often involves lymph nodes, and gastric involvement is rare. Hodgkin's and Reed-Sternberg (H-RS) cells in cHL are known to often lack expression of several B-lineage markers, such as CD20, CD79a, Oct-2, and Bob-1. We present an extremely rare case of mixed-cellularity cHL in the stomach in which expression of these B-cells was detected immunohistochemically. The patient was an 83-year-old Japanese woman who developed a sensation of abdominal fullness and appetite loss. Endoscopic and abdominal computed tomography examinations revealed a gastric ulcer lesion and swelling of para-aortic lymph nodes, respectively. A subtotal gastrectomy was performed, and the histopathologic diagnosis was established as a typical cHL compatible with stomach origin. The patient underwent postoperative chemotherapy of 3 cycles of ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) and has since been in complete remission. Immunohistochemically, the H-RS cells in the cHL were positive not only for CD30 but also for CD20, CD79a, Oct-2, and Bob-1, whereas they were negative for CD3, CD15, CD45, EMA, and ALK1. Our patient may have had an intermediate cHL disease overlapping that of non-Hodgkin's peripheral B-cell lymphoma, possibly reflecting derivation from germinal-center B-cells.

Diagnostic uses of Pax5 immunohistochemistry

Pax5, or B-cell-specific activator protein, is a nuclear protein in the paired-box containing (PAX) family of transcription factors involved in control of organ development and tissue differentiation. Pax5 is mostly expressed in B lymphocytes and B-cell lymphomas, although recent data have shown expression in the developing central nervous system, some neuroendocrine tumors, and occasional myeloid leukemias. Pax5 immunohistochemistry shows robust nuclear staining, and has become a valuable tool in the diagnosis and subclassification of lymphomas. Pax5 staining is positive in most Hodgkin and B-cell non-Hodgkin lymphomas, and also precursor B-cell lymphoblastic neoplasms. Plasma cell neoplasms, multiple myeloma, and plasmablastic lymphomas typically are negative. T-cell lymphomas are, to date, consistently negative. Recently, Pax5 expression has been described in the majority of small cell carcinomas and Merkel cell carcinomas. Rare cases of Pax5 expression in other carcinomas have been reported. With these exceptions, Pax5 immunohistochemistry is fairly specific for B-cell lineage and is a valuable addition to the armamentarium of markers available for lymphoma subtyping.

Bob-1 is expressed in classic Hodgkin lymphoma

Background

Almost all researchers agree on the lack of Bob-1 expression in Hodgkin/Reed-Sternberg (H/RS) cells in classic Hodgkin lymphoma (CHL), and utilize this marker as a diagnostic tool in conjunction with other markers to differentiate between lymphocyte predominance Hodgkin lymphoma (LPHL) and CHL.

Aim

To study the immunohistochemical (IHC) expression of Bob-1 in Egyptian CHL and to correlate this expression with Epstein-Barr virus (EBV) viral load.

Materials and methods

Paraffin sections of randomly selected 18 CHL cases were included: 2 lymphocyte rich (LR), 4 mixed cellularity (MC), 10 nodular sclerosis (NS) and 2 lymphocyte depletion (LD). All cases were immunostained for Bob-1. EBV was evaluated by EBV early RNA transcripts in situ hybridization (EBER ISH) and immunostaining for EBV latent membrane protein-1 (LMP-1).

Results

Sixty seven percent of cases (12/18) were positive for EBV by ISH and/or immunostaining for LMP-1. Moderate to strong nuclear Bob-1 was observed in 94% of cases. The positivity ranged between 25–100%. Bob-1 immunoreactivity was strongly associated with EBV positivity (p < 0.001).

Conclusion

This study proves nuclear IHC expression of Bob-1 on H/RS in CHL implying the difficulties in applying this marker to differentiate between LPHL and CHL. Does this difference between Western and Egyptian CHL reflect genetic and/or environmental factors, or simply no difference exists as most researchers are concentrated on the Western population and no comparative studies have been done. Studies from other countries might answer this question.

New transcription factors in diagnostic hematopathology

The transcription factors (TFs) that controls the intricate machinery of multistep differentiation and activation programs of the lymphoid system, represent a complex array of proteins, whose identification and function has only in part been completed. TFs are usually expressed during specific differentiation or activation cellular programs, making them interesting tools in diagnostic immunohistochemistry. In fact, the specificity of some of these TFs for lineage or activation/differentiation passages or their abnormal expression in specific disease entity, represents a feature that has been exploited in diagnostic/prognostic immunohistochemistry. Bcl-6 was the prototype of this class of markers. Currently, the expanding knowledge of the TFs involved in the differentiation programs and in the activation processes of T-lymphocyte and B-lymphocyte in normal and neoplastic conditions and the availability of antibodies able to efficiently recognize these TFs in histologic material, represent a powerful tool in diagnostic hematopathology. In this review we will consider the basic biologic aspects and the applications in hematopathology of some of the lymphocyte-related TFs, including Pax5/BSAB, MUM1/IRF4, BOB1, Oct-2, T-bet, and FOXP3. This field is rapidly evolving, as witnessed by the ongoing growing number of novel TFs with possible diagnostic applications appearing in the literature.

Lineage determination of CD20- B-Cell neoplasms: an immunohistochemical study

We studied 61 CD20- B-cell lymphomas, including 29 cases of precursor B-cell lymphoblastic leukemia/lymphoblastic lymphoma (B-ALL/B-LBL), 25 cases of CD20- recurrent mature B-cell lymphoma after rituximab therapy, and 7 cases of CD20- diffuse large B cell lymphoma (DLBCL). We used markers specific for B lineage: CD79a, Pax-5, OCT.2, and BOB.1. All B-ALL/B-LBLs expressed Pax-5 (29/29 [100%]), 25 (93%) of 27 expressed BOB.1, 23 (79%) of 29 expressed CD79a, and 6 (22%) of 27 expressed OCT.2. The percentages of cases expressing Pax-5, CD79a, OCT.2, and BOB.1 in CD20- recurrent mature B-cell lymphomas after rituximab treatment were 88% (21/24), 84% (21/25), 81% (17/21), and 73% (16/22), respectively. CD20- DLBCLs rarely express routine B-lineage markers, such as and CD79a and Pax-5, but they expressed OCT.2 or BOB.1. Pax-5, BOB.1, and CD79a antigens are the most reliable B-lineage markers for paraffin immunophenotyping B-ALL/B-LBL. CD79a and Pax-5 should be used as the first-line B lineage-specific markers for rituximab-treated CD20- mature B-cell lymphomas. If negative, OCT.2 or BOB.1 may be useful. The newly identified B-lineage markers, OCT.2 and BOB.1, may be the most useful for the B-lineage determination of CD20- plasmablastic or primary effusion subtypes of DLBCL.