T-cell States, Repertoire, and Function in Classical Hodgkin Lymphoma Revealed through Single-Cell Analyses

The classical Hodgkin lymphoma (cHL) environment is comprised of a dense and complex immune cell infiltrate interspersed with rare malignant Hodgkin-Reed-Sternberg (HRS) cells. HRS cells are actively surveilled by endogenous T cells, but data linking phenotypic and functional T-cell states with clonality at the single-cell level in cHL is lacking. To address this knowledge gap, we performed paired single-cell RNA and T-cell receptor sequencing on 14 cHL and 5 reactive lymphoid tissue specimens. Conventional CD4+ T cells dominated the cHL landscape. However, recurrent clonal expansion within effector and exhausted CD8+ T-cell and regulatory T-cell clusters was uniquely observed in cHL specimens. Multiplex flow cytometric analysis revealed that most lymphoma-resident T cells produced effector cytokines upon ex vivo restimulation, arguing against a profound dysfunctional T-cell state in cHL. Our results raise new questions about the nature of T cells that mediate the antilymphoma response following programmed cell death protein 1 (PD-1) blockade therapy in cHL.

Liquid biopsy: A promising tool for driving strategies and predicting failures in patients with classic Hodgkin lymphoma

Classic Hodgkin lymphoma (cHL) consists of a heterogeneous group of haematological disorders that covers undifferentiated B cell neoplasms originating from germinal centre B cells. The HL molecular characterization still represents an ongoing challenge due to the low fraction of tumour Hodgkin and Reed-Sternberg cells mixed with a plethora of non-tumour haematological cells. In this scenario, next generation sequencing of liquid biopsy samples is emerging as a useful tool in HL patients' management. In this review, we aimed to overview the clinical and methodological topics regarding the implementation of molecular analysis in cHL, focusing on the role of liquid biopsy in diagnosis, follow-up, and response prediction.

Hodgkin Lymphoma: A disease shaped by the tumor micro- and macroenvironment

The tumor microenvironment (TMicroE) and tumor macroenvironment (TMacroE) are defining features of classical Hodgkin lymphoma (cHL). They are of critical importance to clinicians since they explain the common signs and symptoms, allow us to classify these neoplasms, develop prognostic and predictive biomarkers, bioimaging and novel treatments. The TMicroE is defined by effects of cancer cells to their immediate surrounding and within the tumor. Effects of cancer cells at a distance or outside of the tumor define the TMacroE. Paraneoplastic syndromes are signs and symptoms due to effects of cancer at a distance or the TMacroE, which are not due to direct cancer cell infiltration. The most common paraneoplastic symptoms are B-symptoms, which manifest as fevers, chills, drenching night sweats, and/or weight loss. Less common paraneoplastic syndromes include those that affect the central nervous system, skin, kidney, and hematological autoimmune phenomena including hemophagocytic lymphohistiocytosis (HLH). Paraneoplastic signs such as leukocytosis, lymphopenia, anemia, and hypoalbuminemia are prognostic biomarkers. The neoplastic cells in cHL are the Hodgkin and Reed Sternberg (HRS) cells, which are preapoptotic germinal center B cells with a high mutational burden and almost universal genetic alterations at the 9p24.1 locus primarily through copy gain and amplification with strong activation of signaling via PD-L1, JAK-STAT, NFkB, and c-MYC. In the majority of cases of cHL over 95% of the tumor cells are non-neoplastic. In the TMicroE, HRS cells recruit and mold non-neoplastic cells vigorously via extracellular vesicles, chemokines, cytokines and growth factors such as CCL5, CCL17, IL6, and TGF-β to promote a feed-forward inflammatory loop, which drives cancer aggressiveness and anti-cancer immune evasion. Novel single cell profiling techniques provide critical information on the role in cHL of monocytes-macrophages, neutrophils, T helper, Tregs, cytotoxic CD8+ T cells, eosinophils, mast cells and fibroblasts. Here, we summarize the effects of EBV on the TMicroE and TMacroE. In addition, how the metabolism of the TMicroE of cHL affects bioimaging and contributes to cancer aggressiveness is reviewed. Finally, we discuss how the TMicroE is being leveraged for risk adapted treatment strategies based on bioimaging results and novel immune therapies. In sum, it is clear that we cannot effectively manage patients with cHL without understanding the TMicroE and TMacroE and its clinical importance is expected to continue to grow rapidly.

[Progressively transformed germinal center-like follicular T-cell lymphoma:a clinicopathological analysis of 14 cases]

Objective: To investigate the clinicopathologic features of progressively transformed germinal center-like follicular T-cell lymphoma (PTGC-like FTCL). Methods: The clinicopathologic data of 14 PTGC-like FTCL cases that were diagnosed at the Beijing Friendship Hospital Affiliated to the Capital Medical University from January 2017 to January 2022 were retrospectively collected. Clinicopathological features, immunophenotype, and Epstein-Barr virus (EBV) infection status were analyzed in these cases. Polymerase chain reaction (PCR) was performed to detect the clonal gene rearrangements of T cell receptor (TCR) and the immunoglobulin (Ig) in 10 and 8 cases, respectively. Results: The male to female ratio was 5∶2. The median age was 61 years (range 32-70 years). All patients had lymphadenopathy at the time of diagnosis. By using the Ann Arbor system staging, seven cases were classified as stage Ⅰ-Ⅱ, and seven cases as stage Ⅲ-Ⅳ. Seven cases had B symptoms, four cases had splenomegaly, and two cases had skin rash and pruritus. Previously, three cases were diagnosed as classic Hodgkin's lymphoma, three cases as small B-cell lymphoma, two cases as atypical lymphoid hyperplasia unable to exclude angioimmunoblastic T-cell lymphoma (AITL), one case as EBV-associated lymphoproliferative disorder, and one case as peripheral T-cell lymphoma (PTCL) associated with the proliferation of B cells. All the 14 cases showed that the large nodules were composed of mature CD20+, IgD+B lymphocytes admixed with small aggregates of neoplastic cells with pale to clear cytoplasm. Moreover, hyperplastic germinal centers (GCs) and Hodgkin/Reed-Sternberg-like (HRS-like) cells were seen within these nodules in two and five cases, respectively. The neoplastic cells expressed CD3 (14/14), CD4 (14/14), PD1 (14/14), ICOS (14/14), CD10 (9/14), bcl-6 (12/14), CXCL13 (10/14), and CD30 (10/14). The HRS-like cells in five cases expressed CD20 (2/5), PAX5 (5/5), CD30 (5/5), CD15 (2/5), LCA (0/5), OCT2 (5/5) and BOB1 (2/5). Moreover, neoplastic T cells formed rosettes around HRS-like cells. EBV-encoded RNA (EBER) in situ hybridization showed scattered, small, positive bystander B lymphocytes in 8/14 cases, including 3/5 cases containing HRS-like cells. All tested cases (including five with HRS-like cells) showed monoclonal TCR gene rearrangement and polyclonal Ig gene rearrangement. Conclusions: PTGC-like FTCL is a rare tumor originated from T-follicular helper cells. It could be distinguished from angioimmunoblastic T-cell lymphoma by the formation of follicular structure, and lack of follicular dendritic cell proliferation outside the follicles and the polymorphous inflammatory background. In addition, it should be differentiated from lymphocyte-rich classical Hodgkin's lymphoma and low-grade B cell lymphoma.

Classic Hodgkin lymphoma in young people

Classic Hodgkin lymphoma (CHL) is a unique form of lymphoid cancer featuring a heterogeneous tumor microenvironment and a relative paucity of malignant Hodgkin and Reed-Sternberg (HRS) cells with characteristic phenotype. Younger individuals (children, adolescents and young adults) are affected as often as the elderly, producing a peculiar bimodal age-incidence profile that has generated immense interest in this disease and its origins. Decades of epidemiological investigations have documented the populations most susceptible and identified multiple risk factors that can be broadly categorized as either biological or environmental in nature. Most risk factors result in overt immunodeficiency or confer more subtle alterations to baseline health, physiology or immune function. Epstein Barr virus, however, is both a risk factor and well-established driver of lymphomagenesis in a significant subset of cases. Epigenetic changes, along with the accumulation of somatic driver mutations and cytogenetic abnormalities are required for the malignant transformation of germinal center-experienced HRS cell precursors. Chromosomal instability and the influence of endogenous mutational processes are critical in this regard, by impacting genes involved in key signaling pathways that promote the survival and proliferation of HRS cells and their escape from immune destruction. Here we review the principal features, known risk factors and lymphomagenic mechanisms relevant to newly diagnosed CHL, with an emphasis on those most applicable to young people.

Exophthalmos and ocular pain as clinical debut of intracranial Hodgkin's lymphoma at diagnosis

Intracranial involvement in Hodgkin's Lymphoma (HL) is extremely unusual, especially at the time of diagnosis. Because of its non-specific radiological behaviour, it can be confused with more common entities with a radically different prognosis. Pathologically, large and bi-nucleated cells, called Reed-Sternberg cells, embedded in an inflammatory network. In this report we describe the clinical case of a patient, with no medical history, with left ocular pain and exophthalmos as presetation of intracranial HL at diagnosis and review the most current literature. Intracranial involvement is often associated with extracranial disease. Therefore, a systemic study including body computed tomography, bone marrow biopsy and ophthalmological evaluation is necessary. Intracranial lesions respond favourably to treatment and the prognosis depends on the extracranial involvement. To date, there is no standardised management scheme for these patients. For us, the primary role of surgery in this context is to perform a biopsy to confirm the histological diagnosis.

BET inhibitors induce NF-κB and E2F downregulation in Hodgkin and Reed-Sternberg cells

The prognosis of patients with relapsed and/or refractory classic Hodgkin lymphoma (cHL) continues to be poor. Therefore, there is a continuing need to develop novel therapies and to rationalize the use of target combinations. In recent years there has been growing interest in epigenetic targets for hematological malignancies under the rationale of the presence of common alterations in epigenetic transcriptional regulation. Since Hodgkin and Reed-Sternberg (HRS) cells have frequent inactivating mutations of the CREBBP and EP300 acetyltransferases, bromodomain and extra-terminal (BET) inhibitors can be a rational therapy for cHL. Here we aimed to confirm the efficacy of BET inhibitors (iBETs) using representative cell models and functional experiments, and to further explore biological mechanisms under iBET treatment using whole-transcriptome analyses. Our results reveal cytostatic rather than cytotoxic activity through the induction of G1/S and G2/M cell-cycle arrest, in addition to variable MYC downregulation. Additionally, massive changes in the transcriptome induced by the treatment include downregulation of relevant pathways in cHL disease: NF-kB and E2F, among others. Our findings support the therapeutic use of iBETs in selected cHL patients and reveal previously unknown biological mechanisms and consequences of pan-BET inhibition.

The Polyvalent Role of CD30 for Cancer Diagnosis and Treatment

CD30, also known as TNFRSF8 (tumor necrosis factor receptor superfamily member 8), is a protein receptor that is heavily glycosylated inside the Golgi apparatus, as well as a tumor marker that is found on the surface of specific cells in the body, including certain immune cells and cancer ones. This review aims to shed light on the critical importance of CD30, from its emergence in the cell to its position in diagnosing various diseases, including Hodgkin lymphoma, where it is expressed on Hodgkin and Reed-Sternberg cells, as well as embryonal carcinoma, anaplastic large cell lymphoma (ALCL), and cutaneous T-cell lymphoma (CTCL). In addition to its role in positive diagnosis, targeting CD30 has been a promising approach treating CD30-positive lymphomas, and there is ongoing research into the potential use of CD30-targeted therapies for autoimmune disorders. We aim to elaborate on CD30's roles as a tumor marker, supporting thus the hypothesis that this receptor might be the aim of cytostatic treatment.

[The history of Hodgkin lymphoma]

THE HISTORY OF HODGKIN LYMPHOMA. Hodgkin lymphoma was initially considered to be caused by infectious agents. The Hodgkin and Reed-Sternberg tumor cells are derived from mature B cells and transforming events were identified. Staging laparotomy has been discontinued for clinical evaluation with the progress of medical imaging. For seven decades, clinical trials have allowed to define risk factors, to improve standard treatments with the optimal use of chemotherapy and radiotherapy. A risk adapted strategy and early response to chemotherapy are mandatory to reduce long-term consequences of treatment.

Molecular Evolution of Classic Hodgkin Lymphoma Revealed Through Whole-Genome Sequencing of Hodgkin and Reed Sternberg Cells

The rarity of malignant Hodgkin and Reed Sternberg (HRS) cells in classic Hodgkin lymphoma (cHL) limits the ability to study the genomics of cHL. To circumvent this, our group has previously optimized fluorescence-activated cell sorting to purify HRS cells. Using this approach, we now report the whole-genome sequencing landscape of HRS cells and reconstruct the chronology and likely etiology of pathogenic events leading to cHL. We identified alterations in driver genes not previously described in cHL, APOBEC mutational activity, and the presence of complex structural variants including chromothripsis. We found that high ploidy in cHL is often acquired through multiple, independent chromosomal gains events including whole-genome duplication. Evolutionary timing analyses revealed that structural variants enriched for RAG motifs, driver mutations in B2M, BCL7A, GNA13, and PTPN1, and the onset of AID-driven mutagenesis usually preceded large chromosomal gains. This study provides a temporal reconstruction of cHL pathogenesis.

SIGNIFICANCE

Previous studies in cHL were limited to coding sequences and therefore not able to comprehensively decipher the tumor complexity. Here, leveraging cHL whole-genome characterization, we identify driver events and reconstruct the tumor evolution, finding that structural variants, driver mutations, and AID mutagenesis precede chromosomal gains. This article is highlighted in the In This Issue feature, p. 171.

[Treatment strategy for pediatric Hodgkin lymphoma]

Pediatric Hodgkin lymphoma (HL) is a malignant disease that arises from lymphoid reticulum cells, which can metastasize to the spleen, liver, and bone marrow, including the lymph nodes. Classic HL is characterized by the presence of CD30-positive Hodgkin Reed-Sternberg (HRS) cell proliferation. Its symptoms include fever, night sweats, weight loss, itching, splenomegaly, and hepatomegaly, along with painless lymphadenopathy. Although HL has long achieved a high cure rate, late complications such as cardiac complications, infertility, and secondary cancers still pose a threat. The current treatment standard includes a combination of multiagent chemotherapy and low-dose radiation therapy, and attempts have been made to establish a regimen that omits radiation therapy in patients who respond well to initial therapy. The introduction of new molecular-targeted agents is expected to result in further treatment reduction.

[Epigenetic modification as a therapeutic approach for B-cell lymphoma]

Genes that regulate immunological activities are transiently suppressed by epigenetic modification during the germinal center reaction of B cells and reactivated when B cells exit the germinal center. Mutations of EZH2 and other epigenetic modifier genes are frequently involved in the pathogenesis of follicular lymphoma and lead to silencing of the genes necessary for exiting the germinal center. Tazemetostat, an EZH2 inhibitor, has been approved for the treatment of follicular lymphoma with EZH2 gain-of-function mutations in Japan. Tazemetostat restores the expressions of MHC and CD58 in lymphoma cells and synergistically enhances the immune reactions of T and natural killer cells against lymphoma cells. Tazemetostat also induces lymphoma cells to secrete CCL17/TARC and enhances T-cell migration. CD58 and CCL17 are known to play central roles in the formation of T-cell-rich tumor microenvironment of Hodgkin lymphoma. We found that tazemetostat enhances the expression of genes overexpressed in Hodgkin/Reed-Sternberg cells. Epigenetic modifiers and new molecular targeted therapies are expected to provide new insights into the pathogenesis of lymphoma and mechanisms determining the histology of lymphoma.

Cutaneous Lymphadenoma Is a Distinct Trichoblastoma-like Lymphoepithelial Tumor With Diffuse Androgen Receptor Immunoreactivity, Notch1 Ligand in Reed-Sternberg-like Cells, and Common EGFR Somatic Mutations

The term "cutaneous lymphadenoma" was coined in this journal for an unusual lymphoepithelial cutaneous adnexal neoplasm, possibly with immature pilosebaceous differentiation. Some authors further proposed that cutaneous lymphadenoma was an adamantinoid trichoblastoma. However, although a hair follicle differentiation is widely accepted, the fact that this is a lymphoepithelial tumor is not appropriately explained by the trichoblastoma hypothesis. Our goal was to further clarify the phenotypic and genotypic features of cutaneous lymphadenoma in a series of 11 cases. Histologically, a lobular architecture surrounded by a dense fibrous stroma was present in all cases. The lobules were composed of epithelial cells admixtured with small lymphocytes and isolated or clustered large Reed-Sternberg-like (RS-L) cells. The epithelial cells were diffusely positive for the hair follicle stem cell markers CK15, PHLDA1, and for androgen receptor. No immunostaining for markers of sebaceous differentiation was found. Intraepithelial lymphocytes were predominantly CD3+, CD4+, FoxP3+ T cells. RS-L cells showed both strong Jagged-1 and Notch1 cytoplasmic immunostaining. Androgen-regulated NKX3.1 nuclear immunostaining was present in a subset of large intralobular cells in all cases. Double immunostaining showed coexpression of NKX3.1 and CD30 in a subset of RS-L cells. No immunostaining for lymphocytic or epithelial markers was present in RS-L cells. EGFR, PIK3CA, and FGFR3 somatic mutations were found by next-generation sequencing in 56% of the cases. We consider that cutaneous lymphadenoma is a distinct benign lymphoepithelial tumor with androgen receptor and hair follicle bulge stem cell marker expression, RS-L cell-derived Notch1 ligand, and common EGFR gene mutations.

Bioinformatics analysis of whole slide images reveals significant neighborhood preferences of tumor cells in Hodgkin lymphoma

In pathology, tissue images are evaluated using a light microscope, relying on the expertise and experience of pathologists. There is a great need for computational methods to quantify and standardize histological observations. Computational quantification methods become more and more essential to evaluate tissue images. In particular, the distribution of tumor cells and their microenvironment are of special interest. Here, we systematically investigated tumor cell properties and their spatial neighborhood relations by a new application of statistical analysis to whole slide images of Hodgkin lymphoma, a tumor arising in lymph nodes, and inflammation of lymph nodes called lymphadenitis. We considered properties of more than 400, 000 immunohistochemically stained, CD30-positive cells in 35 whole slide images of tissue sections from subtypes of the classical Hodgkin lymphoma, nodular sclerosis and mixed cellularity, as well as from lymphadenitis. We found that cells of specific morphology exhibited significantly favored and unfavored spatial neighborhood relations of cells in dependence of their morphology. This information is important to evaluate differences between Hodgkin lymph nodes infiltrated by tumor cells (Hodgkin lymphoma) and inflamed lymph nodes, concerning the neighborhood relations of cells and the sizes of cells. The quantification of neighborhood relations revealed new insights of relations of CD30-positive cells in different diagnosis cases. The approach is general and can easily be applied to whole slide image analysis of other tumor types.

In pathology, histological diagnosis is still challenging, in particular, for tumor diseases. Pathologists diagnose the disease and its stage of development on the basis of evaluation and interpretation of images of tissue sections. The quantification of experimental data to support decisions of diagnosis and prognosis, applying bioinformatics methods, is an important issue. Here, we introduce a new, general approach to analyze tissue images of tumor and non-tumor patients and to evaluate the distribution of tumor cells in the tissue. Moreover, we consider neighborhood relations between immunostained cells of different cell morphology. We focus on a special type of lymph node tumor, the Hodgkin lymphoma, exploring the two main types of the classical Hodgkin lymphoma, the nodular sclerosis and the mixed cellularity, and the non-tumor case, the lymphadenitis, representing an inflammation of the lymph node. We considered more than 400, 000 cells immunohistochemically stained with CD30 in 35 whole slide images of tissue sections. We found that cells of specific morphology exhibited significant relations to cells of certain morphology as spatial nearest neighbor. We could show different neighborhood patterns of CD30-positive cells between tumor and non-tumor. The approach is general and can easily be applied to other tumor types.

Where does PD-1 blockade fit in HL therapy?

Genetic alterations of the PD-L1/PD-L2 locus on chromosome 9p24.1 are a defining biological feature of classical Hodgkin lymphoma (HL). The resulting programmed death-ligand 1 (PD-L1) expression on Hodgkin Reed-Sternberg cells as well as the PD-L1 expressed in the HL microenvironment result in an ineffective host antitumor immune response and make HL a ripe target for programmed cell death-1 (PD-1) blockade. Anti-PD-1 antibody monotherapy has been effective and well tolerated in patients with relapsed or refractory (rel/ref) HL, with the majority of patients experiencing an objective response (approximately two-thirds of patients) and a median duration of response of 16.6 months in the study with the longest follow-up. Based on these data, nivolumab and pembrolizumab were approved by the US Food and Drug Administration (FDA) for the treatment of advanced rel/ref HL. Evidence has emerged that patients with HL benefit from continued PD-1 blockade beyond disease progression according to traditionally defined response criteria, and that the addition of, or switch to, chemotherapy after anti-PD-1 antibody failure can potentially re-induce clinical response. Subsequent studies have evaluated novel anti-PD-1-based combination regimens as well as the use of anti-PD-1 antibody therapy earlier in the course of a HL patient's therapy, including first salvage therapy for rel/ref disease (eg, nivolumab plus brentuximab vedotin) and even first-line treatment (eg, nivolumab added to doxorubicin, vinblastine, dacarbazine chemotherapy). The current role of PD-1 blockade in HL is as monotherapy in patients with advanced rel/ref disease, but the results of ongoing studies and the evolving treatment landscape in HL will determine the role of PD-1 blockade in the future.

Anterior mediastinal Hodgkin lymphoma presenting as an extremely hypervascular tumor on computed tomography: A case report

RATIONALE

In the thorax, Hodgkin lymphoma (HL) most frequently involves the anterior mediastinal and paratracheal regions and tends to spread to contiguous nodal groups. Enlarged lymph nodes typically have homogeneous soft tissue attenuation similar to that of muscle tissue on computed tomography (CT).

PATIENT CONCERNS

A contrast-enhanced CT examination of a 19-year-old man with right-sided chest pain showed an intense, heterogeneously enhancing mass with organization of serpentine and dilated blood vessels in the right anterior mediastinum that had invaded the upper lobe of the right lung.

DIAGNOSES

Following a wedge resection, histopathological examination showed Reed-Sternberg cells that were positive for CD-15 and CD-30, which is typical of HL.

INTERVENTIONS

The patient was started treatment with 6 cycles of doxorubicin, bleomycin, vincristine, and dacarbazine (ABVD) regimen.

OUTCOMES

After chemotherapy, the patient had shown a partial response to the treatment.

LESSONS

This presentation of HL as an extremely hypervascular anterior mediastinal mass on CT imaging has not been previously reported in the literature. This case suggests that HL should be included in the differential diagnosis of a hypervascular anterior mediastinal mass, especially if the patient is a young adult.

miR-24-3p Is Overexpressed in Hodgkin Lymphoma and Protects Hodgkin and Reed-Sternberg Cells from Apoptosis

miRNAs play important roles in biological processes, such as proliferation, metabolism, differentiation, and apoptosis, whereas altered expression levels contribute to diseases, such as cancers. We identified miRNAs with aberrant expression in Hodgkin lymphoma (HL) and investigated their role in pathogenesis. Small RNA sequencing revealed 84 significantly differentially expressed miRNAs in HL cell lines as compared to germinal center B cells. Three up-regulated miRNAs-miR-23a-3p, miR-24-3p, and miR-27a-3p-were derived from one primary miRNA transcript. Loss-of-function analyses for these miRNAs and their seed family members resulted in decreased growth on miR-24-3p inhibition in three HL cell lines and of miR-27a/b-3p inhibition in one HL cell line. Apoptosis analysis indicated that the effect of miR-24-3p on cell growth is at least in part caused by an increase of apoptotic cells. Argonaute 2 immunoprecipitation revealed 1142 genes consistently targeted by miRNAs in at least three of four HL cell lines. Furthermore, 52 of the 1142 genes were predicted targets of miR-24-3p. Functional annotation analysis revealed a function related to cell growth, cell death, and/or apoptosis for 15 of the 52 genes. Western blotting of the top five genes showed increased protein levels on miR-24-3p inhibition for CDKN1B/P27^kip1 and MYC. In summary, we showed that miR-24-3p is up-regulated in HL and its inhibition impairs cell growth possibly via targeting CDKN1B/P27^kip1 and MYC.

Small lymphocytic lymphoma with Reed Sternberg cells: a diagnostic dilemma

Reed Sternberg (RS) cells in the setting of small lymphocytic lymphoma (SLL) can complicate the histopathological diagnosis. We report a case of a man aged 54 years who presented with cervical lymphadenopathy. Resection of the lymph node was performed and sent for histopathological evaluation to a local laboratory. A diagnosis of SLL with Classic Hodgkin's lymphoma (CHL) was made. The medical oncologist who encountered this diagnosis for the first time sent the biopsy blocks to our laboratory for a second opinion. On review of the biopsy and immunohistochemical stains, it showed typical SLL morphology and immunophenotype. Focally, it showed large mononuclear RS type cells; however, no typical background of CHL was seen. The diagnosis was revised to 'SLL with RS like cells with no convincing evidence of CHL'. The patient was subsequently treated as a case of SLL and no progression was observed on a follow-up of 5 years.

The Use of 3D Telomere FISH for the Characterization of the Nuclear Architecture in EBV-Positive Hodgkin's Lymphoma

The 3D nuclear architecture is closely related to cellular functions and chromosomes are organized in distinct territories. Quantitative 3D telomere FISH analysis (3D Q-FISH) and 3D super-resolution imaging (3D-SIM) at a resolution up to 80 nm as well as the recently developed combined quantitative 3D TRF2-telomere immune FISH technique (3D TRF2/Telo-Q-FISH) have substantially contributed to elucidate molecular pathogenic mechanisms of hematological diseases. Here we report the methods we applied to uncover major molecular steps involved in the pathogenesis of EBV-associated Hodgkin's lymphoma. These methods allowed us to identify the EBV-encoded oncoprotein LMP1 as a key element in the formation of Hodgkin (H-cell) and multinucleated Reed-Sternberg cells (RS-cell), the diagnostic tumor cell of classical Hodgkin's lymphoma (cHL). LMP1 mediates multinuclearity through downregulation of shelterin proteins, in particular telomere repeat binding factor 2 (TRF2).

Expression of Sirt1 and FoxP3 in classical Hodgkin lymphoma and tumor infiltrating lymphocytes: Implications for immune dysregulation, prognosis and potential therapeutic targeting

BACKGROUND

Hodgkin Reed-Sternberg (HRS) cells may promote differentiation of CD4+ naïve T cells toward both FoxP3+ T regulatory (Treg) cells and TIA-1+ cytotoxic T lymphocytes (CTL). Previous studies suggest that an overabundance of cytotoxic TIA-1+ cells in relation to FoxP3+ T reg cells portends unfavorable outcomes in classical Hodgkin lymphoma (cHL), raising the possibility that its pathogenesis may be related to immune dysregulation. Sirt1 deacetylates FoxP3 and leads to decreased Treg functionality. Our objective was to compare Sirt1 and FoxP3 expressions in Hodgkin lymphoma infiltrating lymphocytes (HLIL) and confirm Sirt1 expression in HRS cells.

DESIGN

Immunohistochemical staining of paraffin-embedded tissue with antibodies to Sirt1, FoxP3, TIA-1, and CD8 was performed. Expression of Sirt1 was assessed in both the HRS cells and in the HLILs in twenty-four cases. Adequate tissue was available in 13 cHL cases to permit the enumeration of FoxP3, TIA-1 and CD8 by giving their percent staining of HLILs.

RESULTS

In HLILs, nuclear expression of Sirt1 was 32-88% (mean 67%); FoxP3 expression was 9-40% (mean 23.9%); TIA-1 expression was 15-87% (mean 32%); and CD8 expression was 10-45% (mean = 31%). Sirt1 to FoxP3 ratio was 0.96-5.5 (mean 3.2). TIA-1 to FoxP3 ratio was 0.6-5.1 (mean 1.6). CD8 to FoxP3 ratio was 0.43-3.7 (mean 1.5). There was a difference of Sirt1 to FoxP3 ratios between remission and recurrence groups, being significantly higher in the recurrence group (P = 0.005). Sirt1 demonstrated high nuclear expression in the HRS cells of 21 out of 24 (88%) cases analyzed.

CONCLUSION

The relative overexpression of Sirt1 to FoxP3 in HLILs may be considered possible targets for immune modulation. Histone deacetylase inhibitors may increase the efficacy of existing treatment regimens by downregulating SIRT1 gene mRNA/Sirt1 protein function and together with rapamycin could expand the T regulatory/FoxP3 population and functionality and improve prognosis for remission in cHL. Targeting Sirt1 in the HRS cells may facilitate their ability to promote naïve T cell differentiation toward Treg cells over CTL.

MUM-1 expression differentiates AITL with HRS-like cells from cHL

MUM1 is a member of the interferon regulatory factor family of transcription factors. It is normally expressed in plasma cells, late B cells, and activated T cells, and has been described in several B-cell malignancies and some T-cell neoplasms. The aim of our study was to evaluate the role of MUM-1/IRF4 protein in differentiating angioimmunoblastic T cell lymphoma (AITL) with Hodgkin/Reed-Sternberg (HRS)-like cells from cHL. We identified 12 cases of AITL with HRS-like cells and 24 cases of cHL from March 2013 to November 2014. IHC for MUM-1/IRF4 protein was performed on the tissue of these cases and some relevant positive and negative controls. MUM-1 was expressed in HRS-like cells and some neoplastic T-cells in AITL with HRS-like cells (12/12, 100%) and formed the rosettes around the HRS-like cells (12/12, 100%), expressed in HRS cells in classic Hodgkin Lymphoma (cHL) (24/24, 100%) and just one case formed rosettes around the HRS cells (1/24, 4.2%). Based on the results, MUM-1 could be a useful marker for the differential diagnosis between AITL with HRS-like cells and cHL.

[Clinicopathologic analysis of angioimmunoblastic T-cell lymphoma with Hodgkin/Reed-Sternberg-like cells]

OBJECTIVE

To study the clinicopathologic features and pathologic diagnosis and differential diagnosis of angioimmunoblastic T-cell lymphoma with HRS-like cells.

METHODS

Six cases of angioimmunoblastic T-cell lymphoma with HRS-like cells were examined histologically and immunohistochemically (EliVision method) and in-situ hybridization for Epstein-Barr virus-encoded RNA (EBER), and the literature was reviewed.

RESULTS

The cytologic and microscopic features of these imprints and lymph node samples showed a heterogeneous population of hematolymphoid cells, including small to intermediate lymphoid cells, immunoblasts, plasma cells, dendritic cells, and eosinophils, as well as small vessels that were surrounded by some of the abnormal cells. The neoplastic T-cells expressed CD3 and CD5 and partly positive for CD10 and bcl-6, CD21 showed expanded and irregular follicular dendritic cell (FDC) meshworks that surrounding the high HEV. The HRS-like cells were positive for MUM-1 and Ki-67, variable intensity positive for CD30, CD20, and PAX-5, but negative for CD15. EBV-positive cells included HRS-like cells and small to large-sized neoplastic T-cells, which formed small clusters or scattering in the background of the disease.

CONCLUSIONS

The clinical course of angioimmunoblastic T-cell lymphoma with HRS-like cells is aggressive. Which present with histomorphology overlap with classical Hodgkin lymphoma (CHL), similar to CHL in EBER and immunophenotype, however, it is easy to misdiagnosis as HL. Thus, angioimmunoblastic T-cell lymphoma pathology diagnosis should comprehensive analysis of different kinds of materials, including clinical features, and histological structure, and EBER, and immunophenotype, and gene rearrangement.

Reed-Sternberg cells form by abscission failure in the presence of functional Aurora B kinase

Large multinucleated Reed-Sternberg cells (RS) and large mononucleated Hodgkin cells (H) are traditionally considered to be the neoplastic population in classical Hodgkin lymphoma, (cHL) and postulated to promote the disease. However, the contribution of these larger cells to the progression of cHL remains debatable. We used established cHL cell lines and cHL cellular fractions composed of small mononucleated cells only or enriched in large RS/H cells to investigate RS/H cell origin and to characterize the cells which they derive from. We confirm that the small mononucleated cells give rise to RS/H cells, and we show that the latter proliferate significantly more slowly than the small cells. By using live-cell imaging, we demonstrate that binucleated RS cells are generated by failure of abscission when a few small cells attempt to divide. Finally, our results reveal that the small mononucleated cells are chromosomally unstable, but this is unlikely to be related to a malfunctioning chromosomal passenger protein complex. We propose that the small mononucleated cells, rather than the RS/H cells, are the main drivers of cHL.

HIV-negative Primary Bone Marrow Hodgkin Lymphoma Manifesting with a High Fever Associated with Hemophagocytosis as the Initial Symptom: A Case Report and Review of the Previous Literature

A 68-year-old man was referred to our hospital due to a high fever and pancytopenia. Neither tumors nor infectious lesions were detected. Hemophagocytosis was observed on the bone marrow (BM) smear, although without abnormal cells. Prednisolone therapy was ineffective for the patient's high fever. Later on, we obtained the results of a BM biopsy indicating the presence of infiltration of atypical Reed-Sternberg cells, leading to a diagnosis of HIV-negative primary bone marrow Hodgkin lymphoma (PBMHL). However, the patient died of multiple organ failure before receiving chemotherapy. As the clinical course of PBMHL is rapid, physicians must keep in mind its possibility in similar cases.

Epstein-Barr virus infection is inversely correlated with the expression of retinoblastoma protein in Reed-Sternberg cells in classic Hodgkin lymphoma

Classic Hodgkin lymphoma (cHL) is characterized by few neoplastic Hodgkin/Reed-Sternberg (H/RS) cells in a background of intense inflammatory infiltrate. Epstein-Barr virus (EBV) has been shown to affect cell cycle and regulation of apoptosis. In total, 82 cases of cHL were studied. Five- micrometer sections were prepared and stained with haematoxylin and eosin and immunohistochemical streptavidin-biotin methods for EBV-LMP-1, pRb, ki-67 and cleaved caspase-3. In-situ hybridization for EBV encoded RNA was used to confirm the detection of EBV in H/RS cells. There were 45 nodular sclerosis, 28 mixed cellularity, 4 lymphocyte-rich, and 5 lymphocyte depletion subtypes in this series of cases. EBV and pRb were detected in 55% (46/82) and 64% (50/82) of the cases respectively. EBV was detected in 78% (25/32) of pRb-negative cases and 81% (29/36) of EBV-negative cases are pRb-positive. A statistically significant inverse relationship was observed between the presence of EBV and expression of pRb (P = 0.001). In conclusion, EBV infection is inversely correlated with pRb in H/RS cells in cHL.

A novel immunohistochemical classifier to distinguish Hodgkin lymphoma from ALK anaplastic large cell lymphoma

Classical Hodgkin lymphoma and ALK(-) anaplastic large cell lymphoma share many features like strong CD30 expression and usually loss of B- and T-cell markers. However, their clinical course is dramatically different with curability rates of >90% for classical Hodgkin lymphoma and an unfavorable prognosis for anaplastic large cell lymphoma. Classical Hodgkin lymphoma and ALK(-) anaplastic large cell lymphoma can usually be distinguished by PAX5 expression in the Hodgkin and Reed-Sternberg cells of classical Hodgkin lymphoma and expression of cytotoxic molecules in tumor cells of anaplastic large cell lymphoma. However, in some cases the differential diagnosis is difficult owing to absence of established markers. To be able to better classify these cases, we reevaluated gene expression data of microdissected tumor cells of both lymphomas for differentially expressed genes. A classifier was established, comprising four genes strongly expressed in Hodgkin and Reed-Sternberg cells of classical Hodgkin lymphoma (MDC/CCL22, CD83, STAT3, and TUBB2B). Applying this classifier to a test cohort, Hodgkin lymphoma was successfully distinguished from ALK(-) anaplastic large cell lymphoma with an accuracy of 97% (43/44). MDC/CCL22, CD83, and STAT3 have also been found to be expressed in antigen-presenting cells. Therefore, based on our established classifier, Hodgkin and Reed-Sternberg cells differ from tumor cells of anaplastic large cell lymphoma, which can successfully be applied for practical purposes in histopathologic diagnostics.

[Pathological diagnosis of Hodgkin lymphoma]

This lymphoma was recognized by Thomas Hodgkin in 1832. In 1865, Samuel Wilks named it Hodgkin disease. Now, the term Hodgkin lymphoma (HL) is acceptable over Hodgkin disease. Since the neoplastic cells of the disease is well-recognized to be a lymphoid cell, especially B lymphocyte. In WHO classification published in 2008, HLs are divided into two entities: Classical HL and nodular lymphocyte predominat HL. The former is composed of four different subtypes: nodular sclerosis (NS), mixed cellularity (MC), lymphocyte rich (LR), and lymphocyte depletion (LD). HL is characterized by the morphological feature comprising a minority of neoplastic cells, Hodgkin/Reed-Sternberg cells and popcorn (LP) cells and a majority of non-neoplastic reactive cells. Antigen receptor gene analyses by prevailing molecular methods and flow cytometry are not appropriate method for the diagnosis of HL, because of small number of neoplastic cells. They are, however, very useful in the differential diagnosis to rule out other lymphomas. Even the present when science progressed, pathological (morphological and immunohistochemical) examination is very worth for diagnosis of HL.

Epstein-Barr virus infection correlates with the expression of COX-2, p16(INK4A) and p53 in classic Hodgkin lymphoma

Classic Hodgkin lymphoma (cHL), a germinal-center related B cell neoplasm in almost all cases, is characterized by scarcity of the neoplastic Hodgkin/Reed-Sternberg (H/RS) cells. Epstein-Barr virus (EBV) has been shown to affect cell cycle and regulation of apoptosis. In total, 95 cases of cHL were studied. Five-micrometer sections were prepared and stained with hematoxylin and eosin and immunohistochemical streptavidin-biotin methods for EBV-LMP-1, COX-2, p53, p16, ki-67 and cleaved caspase-3. In-situ hybridization for EBV encoded RNA was used to confirm the detection of EBV in H/RS. There were 49 nodular sclerosis, 32 mixed cellularity, 8 lymphocyte-rich, and 6 lymphocyte-depleted subtypes in this series of cases. EBV, COX-2, p16(INK4A) and p53 were detected in 55% (52/95), 64% (61/95), 62% (59/95), and 65% (62/95) of the cases respectively. EBV was detected in 62% (38/61), 70% (41/59), and 69% (43/62) of COX2, p16 and p53 positive cases respectively. On the other hand, EBV-non-infected cases of cHL are associated with 59% (20/34), 69% (25/36), and 73% (24/33) of COX2, p16 and p53 negative cases respectively. In conclusion, EBV infection is associated with the expression of COX-2, p16(INK4A) and p53. EBV might be the dominant factor in determining the expression of these three proteins.

Matrix metalloproteinase-9 expression by Hodgkin-Reed-Sternberg cells is associated with reduced overall survival in young adult patients with classical Hodgkin lymphoma

Previous studies have investigated the prognostic relevance of MMP9 in classical Hodgkin lymphoma (cHL), with negative results. However, we have found that MMP9 immunoistochemical expression by Hodgkin-Reed-Sternberg cells is associated with reduced overall survival in a subset of young adult Brazilian patients diagnosed with cHL. Additionally, we have observed that MMP9 expression by neoplastic cells in cHL is associated with EBV positivity. These results may support a rational basis for additional studies on the role of this metalloproteinase as a target for therapy in classical Hodgkin lymphoma.

Multiple primary enoral soft tissue manifestations of a Hodgkin lymphoma--case report and literature review

BACKGROUND

Hodgkin lymphoma (HL) are lymphoproliferative neoplasms, histologically comprising of mononuclear and multinucleated Hodgkin and Reed Sternberg cells (HRS). About 4 % of all lymphatic malignancies of the head and neck are HL. The typical disease presents itself as a nodal lesion. Extranodal, enoral soft tissue involvement by HL is very rare.

CASE REPORT

A 73-year-old man with a suspect, ulcerating lesion in the left retromolar region of the mandible was assigned to our hospital. Prior anti-inflammatory therapy has been without success. Subsequently, three biopsies were taken which could only show inflammation. Finally, two biopsies from the left retromolar region and the left inner cheek showed HRS cells with positive expressions of CD15 and CD30 corresponding to a Hodgkin lymphoma. No lymphatic node or bone involvement could be detected. The patient was designated to receive radio-chemotherapy, but died 3 weeks after diagnosis of multiple organ failure. In a literature review, together with this report, nine cases were found concerning primary HL of the oral mucosa. Accordingly, this is the first case of primary multiple extranodal HL in the oral mucosa in absence of lymphatic node involvement.

DISCUSSION

Neither clinical features nor radiological appearances of HL presenting as primary enoral lesions are pathognomonic. Especially when only small biopsy specimens are available, histological diagnosis remains challenging, may lead to a delay in therapy and may result in a significant worse prognosis.

Hodgkin lymphoma

Hodgkin lymphoma (HL), a B cell-derived cancer, is one of the most common lymphomas. In HL, the tumor cells--Hodgkin and Reed-Sternberg (HRS) cells--are usually very rare in the tissue. Although HRS cells are derived from mature B cells, they have largely lost their B cell phenotype and show a very unusual co-expression of markers of various hematopoietic cell types. HRS cells show deregulated activation of multiple signaling pathways and transcription factors. The activation of these pathways and factors is partly mediated through interactions of HRS cells with various other types of cells in the microenvironment, but also through genetic lesions. The transforming events involved in the pathogenesis of HL are only partly understood, but mutations affecting the NF-κB and JAK/STAT pathways are frequent. The dependency of HRS cells on microenvironmental interactions and deregulated signaling pathways may offer novel strategies for targeted therapies.

Solitary skeletal lesion as the primary manifestation of Hodgkin's lymphoma: a case report

BACKGROUND

Hodgkin's lymphoma (HL) is a malignant neoplasm of lymphoid tissues. Cervical lymphadenopathy is the most common head and neck presentation for HL. Although uncommon, extranodal HL observed at the time of diagnosis is well documented and is typically associated with generalized disease or local spread from adjacent lymph nodes. Primary osseous HL is very rare.

CASE

A 23-year-old male presented with a solitary vertebral lesion as primary manifestation of HL.

CONCLUSION

HL should be remembered in the differential diagnosis of lytic lesions, especially involving the vertebrae and pelvic bones.

3D structural and functional characterization of the transition from Hodgkin to Reed-Sternberg cells

Recent research using an innovative 3D quantitative FISH approach of nuclear remodelling associated with the transition from mononuclear Hodgkin to diagnostic multinuclear Reed-Sternberg cells revealed profound changes in the 3D nuclear organization of telomeres. Analogous 3D telomere dynamics were identified in Hodgkin's lymphoma derived cell-lines and diagnostic patient biopsies. These changes were observed in both, EBV positive and EBV-negative Hodgkin's lymphoma and independent of the age of the patients at presentation. Compared to mononuclear Hodgkin cells, multinuclear Reed-Sternberg cells are characterized by a highly significant increase of telomere aggregates, often composed of very short telomeres, telomere shortening and loss. RS-cells with telomere free "ghost" nuclei are regularly observed. The telomere protecting shelterin complex appears to be disrupted and deregulation of DNA-repair mechanisms is observed. Our findings are consistent with the hypothesis that distinct 3D telomere changes and shelterin disruption represent a common pathogenetic denominator in the generation of Reed-Sternberg cells.

Development of a Hodgkin disease tumor in the neck of a patient who previously had undergone complete excision of a hyaline-vascular Castleman disease neck mass

Castleman disease is an uncommon cause of a neck mass. A benign lymphoproliferative disorder, it may be seen as a self-limited unicentric process or as a fulminant multicentric disease with systemic symptoms. The association between Hodgkin disease and Castleman disease has been debated extensively, but this association is rare. The associated Hodgkin disease frequently has been of the interfollicular subtype and typically has coexisted with the multicentric plasma-cell variant of Castleman disease. We report a case of mixed-cellularity Hodgkin disease of the neck in a patient previously diagnosed with hyaline-vascular-type Castleman disease who had undergone complete excision of a neck mass 2 years earlier.

Expression and prognostic significance of Cox-2 and p-53 in Hodgkin lymphomas: a retrospective study

BACKGROUND

Cyclooxygenase (cox) is the rate-limiting enzyme, which catalyzes the conversion of arachidonic acid into prostaglandins and contributes to the inflammatory process. Cyclooxygenase-2 (cox-2), which is one of the two isoforms, plays a role in tumor progression and carcinogenesis. p53 contributes to apoptosis, DNA renewal and cell cycle. Studies concerning the relationship of cox-2 and p53 expressions and carcinogenesis are available, but the association between cox-2 and p53 in Hodgkin lymphoma (HL) is not exactly known.In our study, we examined the association of cox-2 and p53 expression, with age, stage, histopathological subtype, and survival in HL. We also examined correlation between cox-2 and p53 expression.

METHODS

Cox-2 and p53 expressions in Hodgkin-Reed Sternberg cells (HRS) were examined in 54 patients with HL depending on cox-2 expression, stained cases were classified as positive, and unstained cases as negative. Nuclear staining of HRS cells with p53 was evaluated as positive. The classifications of positivity were as follows: negative if<10%; (1+) if 10-25%; (2+) if 25-50%; (3+) if 50-75%, (4+) if >75%.

RESULTS

Cox-2 and p53 expressions were found in 49 (80%) and 29 (46%) patients, respectively. There were differences between histological subtypes according to cox-2 expression (p = 0.012). Mixed cellular (MC) and nodular sclerosing (NS) subtypes were seen most of the patients and cox-2 expression was evaluated mostly in the mixed cellular subtype.There were no statistically significant relationships between p53 and the histopathological subtypes; or between p53, cox-2 and the factors including stage, age and survival; or between p53 and cox-2 expression (p > 0.05).

CONCLUSION

Considering the significant relationship between the cox-2 expression and the subtypes of HL, cox-2 expression is higher in MC and NS subtypes. However the difference between these two subtypes was not significant. This submission must be advocated by studies with large series.

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.

Hodgkin's lymphoma variant of Richter's syndrome

Chronic lymphocytic leukemia/small lymphocitic lymphoma (CLL/SLL) is low-grade malignant lymphoprolipheration, that has tendency to convert to a higher-grade neoplasm over time. More common is the development of a diffuse large cell lymphoma or transformation into prolymphocytic cell population. In rare cases, 0.1-0.5% of patients develop multiple myeloma or Hodgkin's disease. We present 65-year-old female with Hodgkin's variant of Richter's syndrome. On the basis of clinical simptoms, cytological, hystological and immunohistological finding in April 2008 CLL/SLL were diagnosed. The patient was treated with 8 courses of R-CHOP. After 10 months, FNA of the one of the enlarged lymph node on the neck was performed. The diagnosis was Hodgkin's disease. Immuno-hystological studies of the lymph node was consistent with type I Hodgkin's type of Richter's syndrome. Patient was treated with 3 courses of ABVD and radiotherapy.

Hodgkin lymphoma

Hodgkin disease was first described more than 175 years ago. Clinically and histomorphologically, the features of Hodgkin lymphoma are unusual for a lymphoma or for other malignancies. The incidence of Hodgkin lymphoma is estimated to be 7400 new cases per year in the United States, resulting in an age-adjusted yearly rate of 2.7 per 100,000 per year. There have been numerous classifications of non-Hodgkin lymphoma over the years, but the organizational schemes of Hodgkin lymphoma have been stable. This article reviews the diagnosis of the various types of Hodgkin lymphoma classification, diagnosis and differential.

Hodgkin Lymphoma with Unusual Intrasinusoidal Pattern of Infiltration

In spite of recent great advances in our understanding of both Hodgkin lymphoma (HL) and anaplastic large cell lymphoma (ALCL), occasionally there are CD30-positive large cell hematopoietic neoplasms, in which the morphologic and phenotypic features overlap to such an extent that they cannot easily be classified. We report a histologically unusual case of HL that mimicked ALCL, but had phenotypical characteristics of HL. The neoplastic cells resembling Reed-Sternberg cells or Hodgkin cells were mainly situated within sinusoidal spaces, which are characteristically seen in ALCL. However, they showed unequivocal expression of both CD30 and CD15, and no aberrant antigen expression to suggest ALCL (BSAP+, EMA-, LCA-, CD43-, CD2-, CD3-, CD4-, CD45RO-, ALK-, granzymeB-), with negative TCR gene rearrangement and no expression of EBV. HL with intrasinusoidal pattern has rarely been described, but we suggest that, although cases of HL with such a striking sinusoidal pattern are rare, nevertheless do exist. Since the identification of sinusoidal infiltration by CD30-positive neoplastic cells may lead to a mistaken view of ALCL, wide panel of antibodies should be used to confirm the diagnosis.

Hodgkin lymphoma with cutaneous involvement

We report a case of a 54-year-old previously healthy man with Hodgkin lymphoma who presented initially with a solitary cutaneous ulcer. Unlike non-Hodgkin lymphoma subtypes, skin involvement of Hodgkin lymphoma is extremely rare. Furthermore, the prognosis of Hodgkin lymphoma with skin infiltration is felt to be extremely poor. Contrary to other reports, this case demonstrates that a good response with standard therapy is possible.

Molecular biology of Hodgkin lymphoma

Hodgkin lymphoma (HL) is derived from mature B cells and subdivided into classical HL and nodular lymphocyte predominant HL (NLPHL). HL is unique among human B cell lymphomas because of the rarity of the lymphoma cells, the Hodgkin and Reed-Sternberg (HRS) cells in classical HL and the lymphocyte-predominant (LP) cells in NLPHL, which usually account for 0.1% to 10% of the cells in the affected tissues. Moreover, HRS cells are unique in the extent to which they have lost their B cell-typical gene expression pattern. Deregulation of transcription factor networks plays a key role in this reprogramming process. HRS cells show strong constitutive activity of the transcription factor NF-kappaB. Multiple mechanisms likely contribute to this deregulated activation, including signaling through particular receptors and genetic lesions. Inactivating mutations in the TNFAIP3 tumor suppressor gene, encoding a negative regulator of NF-kappaB activity, were recently identified in about 40% of patients with classical HL. HRS cells are latently infected by Epstein-Barr virus in about 40% of patients, and an important role of this virus in HL pathogenesis-in particular for cases in which HRS cells had lost the capacity to express a B-cell receptor due to destructive somatic mutation-was recently substantiated.

The biology of Hodgkin's lymphoma

Hodgkin's lymphoma was first described in 1832. The aetiology of this lymphoma, however, remained enigmatic for a long time. Only within the past 10 years has the B-cell nature of the pathognomonic Hodgkin and Reed-Sternberg (HRS) cells been revealed, along with several recurrent genetic lesions. The pathogenetic role for Epstein-Barr virus infection has also been substantiated. HRS cells in classical Hodgkin's lymphoma have several characteristics that are unusual for lymphoid tumour cells, and the Hodgkin's lymphoma microenvironment is dominated by an extensive mixed, potentially inflammatory cellular infiltrate. Understanding the contribution of all of these changes to the pathogenesis of this disease is essential for the development of novel therapies.