SLAM family receptors and SAP adaptors in immunity.

The signaling lymphocyte activation molecule (SLAM)-associated protein, SAP, was first identified as the protein affected in most cases of X-linked lymphoproliferative (XLP) syndrome, a rare genetic disorder characterized by abnormal responses to Epstein-Barr virus infection, lymphoproliferative syndromes, and dysgammaglobulinemia. SAP consists almost entirely of a single SH2 protein domain that interacts with the cytoplasmic tail of SLAM and related receptors, including 2B4, Ly108, CD84, Ly9, and potentially CRACC. SLAM family members are now recognized as important immunomodulatory receptors with roles in cytotoxicity, humoral immunity, autoimmunity, cell survival, lymphocyte development, and cell adhesion. In this review, we cover recent findings on the roles of SLAM family receptors and the SAP family of adaptors, with a focus on their regulation of the pathways involved in the pathogenesis of XLP and other immune disorders.

B Cell Lymphomas of the GI Tract.

PURPOSE OF THE REVIEW: Primary GI lymphomas of B cell origin are a diverse group of lymphomas. In this article, we provide an overview of the diagnosis, pathologic and molecular features, and management of these varied lymphomas. RECENT FINDINGS: The most common primary GI lymphomas are diffuse large B cell lymphoma (DLBCL) and marginal zone lymphomas (MZL), but follicular lymphomas (FL), mantle cell lymphomas (MCL), post-transplant lymphoproliferative disorders (PTLD), and Burkitt lymphoma of the GI tract also occur. Many features of these lymphomas are similar to their nodal counterparts, but certain clinical and biological aspects are unique. Diagnostic and treatment strategies for these lymphomas continue to evolve over time. There are ongoing discoveries about the unique pathophysiology, molecular characteristics, and complications of primary B cell GI lymphomas that are already leading to improvements in management of this histologically diverse set of lymphomas.

[Clinicopathological features of indolent T-cell lymphoproliferative disorder of the gastrointestinal tract: a report of five cases].

Objective: To investigate the clinicopathological features of indolent T-cell lymphoproliferative disorder of the gastrointestinal tract. Methods: Five cases of indolent T-cell lymphoproliferative disorder of the gastrointestinal tract from the Affiliated Hospital of Qingdao University from 2016 to 2019 were retrospectively reviewed. The clinical and pathological parameters were analyzed by combining clinical data and reviewing the available literature of 35 cases (34 cases abroad and 1 case in China). Results: There were 4 males and 1 female with a median age of 47 years (18-66 years). All patients had abdominal pain and constitutional symptoms including diarrhea, emaciation, intermittent mucous stool or oral and epiglottic ulcers. Endoscopic manifestations included multiple punctate congestion, erosion and ulcer at the terminal ileum and colorectum. Two cases had congestion and erosion of antrum and angle of stomach, and the lesions did not fuse and form tumors. Histologically, the lamina propria was expanded by a dense, medium to small lymphocyte infiltration, which was monomorphic, with slightly irregular nuclei without prominent nucleolus or lymphoepithelial lesions. There were admixed small amount of plasma cells and eosinophils. In 4 cases, immunohistochemistry showed the lesional cells were positive for CD3, CD8, TIA1, and negative for CD4, CD56, granzyme B and Ki-67 index was ≤10%. In situ hybridization showed that EBER was negative and clonal TCR gene rearrangement was detected. One consultation case was CD3(+), CD5(-) and Ki-67 index of 10%, although other indicators were not done. All five patients were treated with symptomatic support. In follow-up observation for 2 to 25 months, all patients were alive with the disease. Conclusions: Indolent T-cell lymphoproliferative disorder of the gastrointestinal tract is a newly classified monoclonal T-cell proliferative disease, with low incidence, clinical inertia and long-term survival. It has unique clinicopathological features but pathologically it is easily misdiagnosed as inflammatory bowel disease or T-cell lymphoma. Correct diagnosis is of great important clinical significance.

Inhibitory 2B4 contributes to NK cell education and immunological derangements in XLP1 patients.

X-linked lymphoproliferative disease 1 (XLP1) is an inherited immunodeficiency, caused by mutations in SH2D1A encoding Signaling Lymphocyte Activation Molecule (SLAM)-associated protein (SAP). In XLP1, 2B4, upon engagement with CD48, has inhibitory instead of activating function. This causes a selective inability of cytotoxic effectors to kill EBV-infected cells, with dramatic clinical sequelae. Here, we investigated the NK cell education in XLP1, upon characterization of killer Ig-like receptor (KIR)/KIR-L genotype and phenotypic repertoire of self-HLA class I specific inhibitory NK receptors (self-iNKRs). We also analyzed NK-cell cytotoxicity against CD48+ or CD48- KIR-ligand matched or autologous hematopoietic cells in XLP1 patients and healthy controls. XLP1 NK cells may show a defective phenotypic repertoire with substantial proportion of cells lacking self-iNKR. These NK cells are cytotoxic and the inhibitory 2B4/CD48 pathway plays a major role to prevent killing of CD48+ EBV-transformed B cells and M1 macrophages. Importantly, self-iNKR defective NK cells kill CD48- targets, such as mature DCs. Self-iNKR- NK cells in XLP1 patients are functional even in resting conditions, suggesting a role of the inhibitory 2B4/CD48 pathway in the education process during NK-cell maturation. Killing of autologous mature DC by self-iNKR defective XLP1 NK cells may impair adaptive responses, further exacerbating the patients' immune defect.

Autophagy as a pathogenic mechanism and drug target in lymphoproliferative disorders.

Autophagy represents a key mechanism of cytoprotection that can be activated by a variety of extracellular and intracellular stresses and allows the cell to sequester cytoplasmic components and damaged organelles, delivering them to lysosomes for degradation and recycling. However, the autophagy process has also been associated with the death of the cell. It has been demonstrated to be constitutive in some instances and inducible in others, and the idea that it could represent a pathogenetic determinant as well as a possible prognostic tool and a therapeutic target in a plethora of human diseases has recently been considered. Among these, cancer represents a major one. In this review, we recapitulate the critical implications of autophagy in the pathogenesis, progression, and treatment of lymphoproliferative disorders. Leukemias and lymphomas, in fact, represent paradigmatic human diseases in which advances have recently been made in this respect.

BIRC4 Mutation: An Important Rare Cause of Uveitis.

We report a 6-year-old man with chronic severe recalcitrant bilateral anterior uveitis and a remote history of hemophagocytic lymphocytic histiocytosis secondary to Epstein-Barr virus infection. The patient was treated for idiopathic uveitis after an initial extensive evaluation failed to reveal a specific diagnosis. The patient failed to achieve sustained inactive disease with multiple monotherapies including topical glucocorticoid, methotrexate, infliximab, mycophenolate mofeti, and cyclosporine. Disease control was finally attained with a combination of cyclosporine and adalimumab. After more recent testing, he was found to have a novel deletion on the BIRC4 (baclovirus inhibitor of apoptosis repeat containing protein 4) gene, the causative gene for X-linked lymphoproliferative syndrome type 2. We conclude that male patients with chronic idiopathic uveitis should be questioned about a history of hemophagocytic lymphocytic histiocytosis during their workup and screened for BIRC4 mutation if appropriate.

Posttransplantation lymphoproliferative disease: proposed imaging classification.

Posttransplantation lymphoproliferative disease (PTLD) is the second most common tumor in adult transplant recipients. Most cases of PTLD are attributed to Epstein-Barr virus. Decreased levels of immunosurveillance against this tumor virus as a result of immunosuppressive regimens are thought to account for most cases of PTLD. Histologically, PTLD ranges from relatively benign lymphoid hyperplasia to poorly differentiated lymphoma, and tissue sampling is required to establish the subtype. The frequency of PTLD varies depending on the type of allograft and immunosuppressive regimen. PTLD has a bimodal manifestation, with most cases occurring within the first year after transplantation and a second peak occurring 4-5 years after transplantation. Patients are often asymptomatic or present with nonspecific symptoms, and a mass visible at imaging may be the first clue to the diagnosis. Imaging plays an important role in identifying the presence of disease, guiding tissue sampling, and evaluating response to treatment. The appearance of PTLD at imaging can vary. It may be nodal or extranodal. Extranodal disease may involve the gastrointestinal tract, solid organs, or central nervous system. Solid organ lesions may be solitary or multiple, infiltrate beyond the organ margins, and obstruct organ outflow. Suggestive imaging findings should prompt tissue sampling, because knowledge of the PTLD subtype is imperative for appropriate treatment. Treatment options include reducing immunosuppression, chemotherapy, radiation therapy, and surgical resection of isolated lesions.

PUMA protein in p53 regulatory molecule pattern determines the prognosis for patients with lymphoproliferative diseases.

The pool of apoptosis regulator proteins (p53, PUMA, p21, and MDM2) in the bone marrow, lymph node, and other tumor substrate cells were studied by immunocytochemical analysis in patients with chronic lymphoproliferative diseases. Two groups of patients were distinguished, with the disease course differing by activities of the studied molecules. Activity of p53 was the minimum in the group with benign course of the disease, and protein p21 was not detected; MDM2 protein was present in moderate amounts in the presence of high PUMA activity. High activities of p53, p21, and MDM2 and low PUMA activity were found in tumor cells of patients with malignant disease. These data can serve as a prognostic sign determining the aggressiveness of chronic lymphoproliferative disease course and for determining the strategy of chemotherapy and its correction.

Alterations of negative regulators of cytokine signalling in immunodeficiency-related non-Hodgkin lymphoma.

We investigated immunodeficiency-related non-Hodgkin lymphoma for the presence of molecular alterations affecting negative regulators of the Janus family protein tyrosine kinase/signal transducer and activator of transcription pathway. Protein tyrosine phosphatase, non-receptor type 6/Src homology 2-containing tyrosine phosphatase-1 epigenetic silencing was recurrent in primary effusion lymphoma (100%), and diffuse large B-cell lymphoma (63%), with a higher prevalence in the non-germinal centre subtype, and was associated with the activation of the Janus family protein tyrosine kinase/signal transducer and activator of transcription 3 pathway. Suppressor of cytokine signalling (SOCS)1 and SOCS3 epigenetic silencing were occasionally detected, whereas SOCS1 was frequently mutated in diffuse large B-cell lymphoma and polymorphic post-transplant lymphoproliferative disorders, possibly as a cause of aberrant somatic hypermutation. However, the mutation profile of the coding region of the gene was different from that expected from the aberrant somatic hypermutation process, suggesting that, at least in some cases, SOCS1 mutations may have been selected for their functional activity.

CXCL13 as a novel marker for diagnosis and disease monitoring in pediatric PTLD.

Posttransplant lymphoproliferative disease (PTLD) is a severe complication of immunosuppressive treatment in organ-grafted children. Early diagnosis of PTLD is hampered by both unspecific clinical symptoms and lack of easy accessible markers. The homeostatic chemokine CXCL13, which plays a crucial role in B-cell homing and lymphoid organ development, is expressed in some lymphomatous diseases. This study aims to investigate whether serum CXCL13 (sCXCL13) levels correlate with occurrence and regression of PTLD in pediatric solid-organ graft recipients. Serum samples from PTLD patients (n = 21), patients with Epstein-Barr virus (EBV) reactivation (n = 18), and healthy age-matched controls (n = 19) were tested for CXCL13 using a commercially available ELISA kit. sCXCL13 levels were significantly higher in PTLD patients than in healthy children. PTLD patients had also higher sCXCL13 values than pediatric solid-organ recipients with EBV reactivation. An increase in sCXCL13 levels was observed from EBV reactivation to PTLD diagnosis in most cases. Elevated sCXCL13 levels were detected up to 2 years prior to PTLD diagnosis and correlated well with response to cytoreductive treatment in individual patients. sCXCL13, thus, may be a readily available surrogate marker for the diagnosis of PTLD and for monitoring of response to treatment in patients with initially elevated sCXCL13 levels.

A 16-year multi-institutional study of the role of age and EBV status on PTLD incidence among pediatric heart transplant recipients.

The objective was to determine the incidence and hazard for posttransplant lymphoproliferative disease (PTLD) in a study of 3170 pediatric primary heart transplants between 1993 and 2009 at 35 institutions in the Pediatric Heart Transplant Study. 147 of 151 reported malignancy events were classified as PTLD. Overall freedom from PTLD was 98.5% at 1 year, 94% at 5 years and 90% at 10 years. Freedom from PTLD was lowest in children (ages 1 to < 10 years) versus infants (<1 year) and adolescents (10 to < 18 years) with children at highest risk for PTLD with a relative risk of 2.4 compared to infants and 1.7 compared to adolescents. Positive donor EBV status was a strong risk factor for PTLD in the seronegative recipient, but risk magnitude was dependent on recipient age at the time of transplantation. Nearly 25% of EBV seronegative recipients of EBV+ donors at ages 4-7 at transplantation developed some form of PTLD. The overall risk for PTLD declined in the most recent transplant era (2001-2009, p = 0.003). These findings indicate that EBV status and the age of the recipient at the time of transplantation are important variables in the development of PTLD in the pediatric heart transplant recipient.

NT-pro-BNP: not the prognostic all-rounder in elderly patients undergoing allogeneic stem cell transplantation.

Allogeneic hematopoietic cell transplantation (HCT) is a curative approach for several diseases predominantly affecting elderly patients. Overall survival is compromised by treatment-related mortality (TRM), GvHD, and relapse. Pretransplant clinical risk indicators in elderly patients qualifying for HCT are highly desirable. Pro-BNP is known as a predictor of death in patients with an increasing variety of clinical conditions and frequently used as a routine parameter for organ complications in the allogeneic transplant setting without well-established scientific evidence. Our hypothesis was that pre-HCT NT-pro-BNP could aid in identifying elderly patients at risk for early mortality. We retrospectively evaluated NT-pro-BNP values in 177 consecutive patients of ≥60 years HCT (2005-2010). In 29.4 % of cases, NT-pro-BNP values were within our institute's normal range (<125 pg/ml). Analysis of different NT-pro-BNP cutoff points by receiver operating characteristics curve for mortality at day +100 revealed no single cutoff value with satisfying specificity and sensitivity. The individual outcome of patients with extremely high NT-pro-BNP values was not associated with an increase in mortality or cardiovascular morbidity. NT-pro-BNP values of patients succumbing to TRM did not differ significantly from those alive or having died of relapse-median 276 vs. 217 pg/ml. In conclusion, pre-HCT NT-pro-BNP was of no convincing prognostic relevance for day 100 mortality.

Atypical hydroa vacciniforme-like epstein-barr virus associated T/NK-cell lymphoproliferative disorder.

Epstein-Barr virus (EBV)-associated T-cell/natural killer (NK)-cell lymphoproliferative disorders (EBV-T/NK-LPDs) accompany severe chronic active EBV infection (CAEBV) or comprise the CAEBV disease entity. The CAEBV disease entity has the common feature of lymphoproliferation of T or NK cells (primarily), and B cells (rarely), with chronic activation of EBV infection. The disease is rare and seems to be more prevalent in East Asian countries. The CAEBV disease entity encompasses heterogenous disorders, including hydroa vacciniforme (HV), hypersensitivity to mosquito bites, EBV-associated hemophagocytic syndrome, NK/T-cell lymphoma, and NK-cell leukemia. Atypical HV-like eruptions are present on sun-exposed and nonexposed areas with facial edema, fever, and hepatosplenomegaly, unlike classic HV. Recently, it has been suggested that classic HV and atypical HV-like eruptions are variants within the same disease spectrum of EBV-T/NK-LPD. We report a Korean boy with an atypical HV-like eruption and various systemic manifestations, including fever, sore throat, abdominal pain, headaches, seizures, and hematologic abnormalities for 2 years. After the initial mild eruption, which resembled a viral exanthem, ulceronecrotic skin lesions gradually developed and were associated with a high-grade fever and constitutional symptoms. He had a CAEBV infection, which showed a predominant proliferation of NK cells with high EBV DNA levels in the peripheral blood. However, in the skin lesions, there were nonneoplastic CD4 T-cell infiltrations predominantly showing a monoclonal T-cell receptor-γ gene rearrangement and positive EBV in situ hybridization.

[HCV-associated cryoglobulinemic vasculitis].

AIM: To analyze clinical and laboratory features of cryoglobulinemic vasculitis (CGEV) associated with HCV infection. MATERIAL AND METHODS: We examined 61 patients with clinical manifestation of CGEV in 2006-2011. CGEV was associated with autoimmune diseases in 31 patients (51%), with HCV infection in 21 patients (34.4%), essential (idiopathic) ctyoglobulinemia in 8 patients (13%) and lymphoproliferative diseases in 1 patient (1.6%). 21 patients with HCV-associated CGEV were studied for main clinical and laboratory manifestations of the disease. Kidney and liver involvement was confirmed morphologically and immunomorphologically. Electroneurophysiological investigation evaluated peripheral nervous system involvement. Biopsy of parotid, lacrimal glands., peripheral lymph nodes, splenectomy and bone marrow trephine biopsy with morphological study and immunohistochemistry were used to identify type of lymphoma. Characteristics of monoclonal secretion were assessed with high-resolution electrophoresis in agarose gel with subsequent immunofixation of sera and concentrated urine. RESULTS: Liver involvement was detected in 66% of patients with HCV-associated CGEV 34% patients were chronic HCV carriers with persistently normal liver function tests. Common rheumatologic manifestations of HCV-associated CGEV were skin lesions (90%), arthralgia (85%), frequent peripheral nervous system involvement (52%) and glomerulonephritis (38%). Prevalent immunological markers of CGEV associated with HCV were mixed monoclonal cryoglobulinemia with rheumatoid factor activity (62%), rare polyclonal (34%) and olygoclonal (4%) cryoglobulinemia, low levels of C4 compliment fraction (80%). Patients with mixed monoclonal cryoglobulinemia often developed clinical manifestations of Sjögren's syndrome (23%) and malignant lymphoproliferative diseases (14%). CGEV is a prognostically adverse sign in HCV infected patients and caused death of 14% patients even in a short period of follow-up (1-2 years).

Caspase-8 deficiency in T cells leads to a lethal lymphoinfiltrative immune disorder.

Caspase-8 is best known for its cell death function via death receptors. Recent evidence indicates that caspase-8 also has nonapoptotic functions. Caspase-8 deficiency is associated with pathologies that are unexpected for a proapoptotic molecule, such as abrogation of activation-induced lymphocyte proliferation, perturbed immune homeostasis, and immunodeficiency. In this study, we report the long-term physiological consequences of T cell-specific deletion of caspase-8 (tcasp8-/-). We show that tcasp8-/- mice develop an age-dependent lethal lymphoproliferative and lymphoinfiltrative immune disorder characterized by lymphoadenopathy, splenomegaly, and accumulation of T cell infiltrates in the lungs, liver, and kidneys. Peripheral casp8-/- T cells manifest activation marker up-regulation and are proliferating in the absence of any infection or stimulation. We also provide evidence suggesting that this immune disorder is different from the autoimmune lymphoproliferative syndrome. Interestingly, the condition described in tcasp8-/- mice manifests features consistent with the disorder described in humans with Caspase-8 deficiency. These findings suggest that tcasp8-/- mice may serve as an animal model to evaluate Caspase-8-deficient patient prognosis and therapy. Overall, our study uncovers novel in vivo functions for caspase-8 in immune regulation.

CTLA-4 blockade following relapse of malignancy after allogeneic stem cell transplantation is associated with T cell activation but not with increased levels of T regulatory cells.

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is a key negative regulator of T cell activation and proliferation. Ipilimumab is a human monoclonal antibody that specifically blocks the binding of CTLA-4 to its ligand. To test the hypothesis that blockade of CTLA-4 by ipilimumab could augment graft-versus-malignancy (GVM) effects without a significant impact on graft-versus-host disease (GVHD), we conducted a phase I clinical trial of ipilimumab infusion in patients with relapsed malignancy following allogeneic hematopoietic stem cell transplantation (allo-HSCT). Here, we report the analysis of peripheral blood T lymphocyte reconstitution, T regulatory cell (Treg) expression, and T cell activation markers after a single dose of ipilimumab in 29 patients. Peripheral blood samples were collected from all patients before and after ipilimumab infusion. Lymphocyte immunophenotyes, including levels of CD4(+)CD25(high) cells and T cell activation markers, were analyzed in all cases. Levels of CD4(+)CD25(high)Foxp3(+) cells and intracellular CTLA-4 in CD4(+) T cells also were evaluated in the last 11 cases. We found lower baseline levels of CD4(+) and CD45RO(+) T cells in patients compared with normal controls. More than 50% of the patients had abnormally low lymphocyte counts (CD4 or/and CD8 T cells), and some had no circulating B lymphocytes. The percentages of both CD4(+)CD25(high) and CD4(+)CD25(high)Foxp3(+) T cells were significantly higher in patients before ipilimumab infusion than in healthy donors. Twenty of 29 patients exhibited an elevated level of CD4(+)CD25(low) activated T cells at baseline, compared with only 3 of 26 healthy donors. Both CD4(+) and CD8(+) T lymphocyte counts were significantly increased after ipilimumab infusion. There was no consistent change in absolute lymphocyte count or in the number of T cells expressing the activation marker CD69. However, increases in CD4(+)CD25(low) T cells were seen in 20 of 29 patients and increases in CD4(+)HLA-DR(+) T cells were seen in the last 10 patients in the first 60 days after ipilimumab infusion. Although the percentages of both CD4(+)CD25(high) and CD4(+)CD25(high)Foxp3(+) T cells decreased significantly during the observation period, the absolute cell counts did not change. Intracellular CTLA-4 expression in CD4(+)CD25(lo/-) T cells increased significantly after ipilimumab infusion. We conclude that CTLA-4 blockade by a single infusion of ipilimumab increased CD4(+) and CD4(+)HLA-DR(+) T lymphocyte counts and intracellular CTLA-4 expression at the highest dose level. There was no significant change in Treg cell numbers after ipilimumab infusion. These data demonstrate that significant changes in T cell populations occur on exposure to a single dose of ipilimumab. Further studies with multiple doses are needed to explore this phenomenon further and to correlate changes in lymphocyte subpopulations with clinical events.

Castleman's disease: from basic mechanisms to molecular therapeutics.

Castleman's disease is a rare lymphoproliferative disorder in which there has been recent progress in elucidating underlying mechanisms with potential therapeutic implications. Unicentric Castleman's disease is an indolent condition that is often treated with local approaches. In contrast, patients with multicentric Castleman's disease (MCD) have a less favorable prognosis and require systemic treatment. Cytotoxic chemotherapy, with its attendant risk for toxicity, has been widely used to treat MCD, with variable efficacy. The discovery of putative etiologic factors and targets in MCD, particularly human herpes virus 8, CD20, and interleukin (IL)-6, has been translated into the use of rituximab and anti-IL-6-based therapy, as well as antiviral agents. In this article, we review the current state of the art of our understanding of Castleman's disease and its treatment and we provide insight into future treatment strategies based on disease biology.

Notch-deficient skin induces a lethal systemic B-lymphoproliferative disorder by secreting TSLP, a sentinel for epidermal integrity.

Epidermal keratinocytes form a highly organized stratified epithelium and sustain a competent barrier function together with dermal and hematopoietic cells. The Notch signaling pathway is a critical regulator of epidermal integrity. Here, we show that keratinocyte-specific deletion of total Notch signaling triggered a severe systemic B-lymphoproliferative disorder, causing death. RBP-j is the DNA binding partner of Notch, but both RBP-j-dependent and independent Notch signaling were necessary for proper epidermal differentiation and lipid deposition. Loss of both pathways caused a persistent defect in skin differentiation/barrier formation. In response, high levels of thymic stromal lymphopoietin (TSLP) were released into systemic circulation by Notch-deficient keratinocytes that failed to differentiate, starting in utero. Exposure to high TSLP levels during neonatal hematopoiesis resulted in drastic expansion of peripheral pre- and immature B-lymphocytes, causing B-lymphoproliferative disorder associated with major organ infiltration and subsequent death, a previously unappreciated systemic effect of TSLP. These observations demonstrate that local skin perturbations can drive a lethal systemic disease and have important implications for a wide range of humoral and autoimmune diseases with skin manifestations.

Classical Hodgkin's lymphoma arising in different host's conditions: pathobiology parameters, therapeutic options, and outcome.

Epidemiologic and molecular findings suggest that classical Hodgkin's lymphoma (CHL) is not a single disease but consists of more than one entity and may occur in different clinical settings. This review analyzes similarities and disparities among CHL entities arising in different host's conditions with respect to pathobiology parameters, therapeutic options, and outcome. For the purpose of this analysis, CHL entities have been subdivided according to the immune status of the host. In nonimmunosuppressed hosts, according to the age, CHL include pediatric, adult, and elderly forms, whereas, in immunosuppressed hosts, according to the type of immunosuppression, CHL include human immunodeficiency virus (HIV)-associated, iatrogenic, and post-transplant types. CHL entities in different settings are similar in morphology of neoplastic cells, expression of activation markers, and aberrations/activation of NFKB, JAK/STAT, and P13K/AKT pathways, but differ in the association with Epstein-Barr virus (EBV) infection, persistent B-cell phenotype, and cellular background composition. Large B-cell lymphomas resembling CHL may also be observed in the same clinical settings. These lesions, however, do not fulfill the diagnostic criteria of CHL and clinically display a very aggressive behavior. In this article, current treatment options for the CHL entities, especially for elderly CHL and HIV-associated CHL, are specifically reviewed. ABVD remains the gold standard both in nonimmunosuppressed or immunosuppressed hosts even if there are several data suggesting a possible improvement in outcome using the aggressive BEACOPP regimen in advanced stages. Refractory CHL, a clinical condition that may occur throughout the entire spectrum of CHL, is discussed separately.