Diffuse large B-cell lymphoma (DLBCL) is divided into germinal center B-like (GCB) DLBCL and activated B-like (ABC) DLBCL. In recent years, whole genome sequencing (WGS), whole exome sequencing (WES), and transcriptome sequencing (RNA-seq) have been performed for samples from many patients with DLBCL. Here, I present a review of the results of next generation sequencing data for DLBCL. Somatic mutations show a low identity between studies with only 10–20% gene overlap. DLBCL is a disease that results from various molecular pathogeneses. Mutations in genes involved in chromatin remodeling were found in the GCB subtype. Mutations in members of B-cell receptor (BCR) signaling and the NF-κB pathway (MYD88) were found in the ABC subtype. The MYD88 L265P mutation was observed in 29% of ABC DLBCL cases. EZH2 mutations were observed in 21.7% of GCB DLBCL cases. WGS indicated that inactivating mutations in GNA13 (Gα protein) were prevalent in GCB DLBCL cases. In addition, S1PR2 is a target of aberrant somatic hypermutation. In recent years, samples from patients with relapsed and refractory DLBCL were analyzed. The activation of the NF-κB pathway is associated with treatment resistance in DLBCL. Further clarification of the molecular pathogenesis of DLBCL is expected to lead to the development of individualized treatment for the disease.
Diffuse large B-cell lymphoma (DLBCL) comprises a heterogeneous group with pathophysiological, genetic and clinical features. Many patients can be cured with R-CHOP therapy, which is the current standard regimen. Despite recent progress in improving patient survival, the 40% survival of DLBCL patients remains poor. Therefore, the most important issue for patients with DLBCL remains the development of a new front-line therapy. Several studies have reported that intensified chemotherapy with dose-adjusted EPOCH-R or R-ACVBP was superior to R-CHOP. Gene expression profiling has identified two distinct forms of DLBCL: activated B cell-like (ABC) and germinal center B-cell-like (GCB) types. ABC DLBCL exhibits a worse prognosis than GCB DLBCL by molecular diagnosis after R-CHOP therapy. Next-generation sequencing has identified unique oncogenic mechanisms and genetic complexity, which has provided rational therapeutic targets. There are also a number of biomarkers, including CD5, and prognostic factors. Efforts to distinguish many biomarkers will be crucial for individualized treatment in the future.
CD20 is a differentiation related cell surface phosphoprotein that is expressed during early pre-B cell stages until plasma cell differentiation, and is a suitable molecular target for B-cell malignancies by monoclonal antibodies such as rituximab, ofatumumab, obinutuzumab and others. CD20 expression is confirmed in most B-cell malignancies; however, the protein expression level varies in each patient, even in de novo tumors, and down-modulation of CD20 expression after chemoimmunotherapy with rituximab, resulting in rituximab resistance, has been recognized in the clinical setting. Recent reports suggest that genetic and epigenetic mechanisms are correlated with aberrantly low CD20 expression in de novo tumors and relapsed/refractory disease after using rituximab. Furthermore, some targeting drugs, such as lenalidomide, bortezomib and ibrutinib, directly or indirectly affect CD20 protein expression. CD20-negative phenotypically-changed DLBCL after rituximab use tends to show an aggressive clinical course and poor outcome with resistance to not only rituximab, but also conventional salvage chemo-regimens. Understanding of the mechanisms of CD20-negative phenotype may contribute to establish strategies for overcoming chemo-refractory B-cell malignancies. In this manuscript, recent progress of research on molecular and clinical features of CD20 protein and CD20-negative B-cell malignancies was reviewed.
High-dose chemotherapy supported by autologous stem cell support/transplantation (HDT/ASCT) has been a standard of care over the last two decades in patients with relapsed or refractory(R/R) diffuse large B-cell lymphoma (DLBCL), which is sensitive to salvage chemotherapy. HDT/ASCT for high-risk DLBCL in upfront setting remains controversial, so it is not recommended for clinical practice. Various promising salvage chemotherapy regimens have been reported in phase 2 studies; however, two large randomized phase 3 studies showed similar efficacy of R-ICE vs. R-DHAP and R-GDP vs. R-DHAP. Since the registry data shows feasibility and efficacy of HDT/ASCT in elderly R/R DLBCL patients, older age (> 65 years) itself is not a contraindication for HDT/ASCT. Rituximab maintenance failed to demonstrate a significant benefit compared with observation only after HDT/ASCT. While sensitive R/R DLBCL might be cured by HDT/ASCT even in third-line therapy, the prognosis of insensitive R/R DLBCL is extremely poor. Further study to establish treatment strategies for high-risk patients defined by prognostic factors or biomarkers, and insensitive patients is warranted.
Langerhans cell (LC) histiocytosis (LCH) and LC sarcoma (LCS) are proliferative processes consisting of cells having morphologic and phenotypic features of Langerhans cells (LCs), although the latter may have lost some of these features. Because neoplastic nature of LCH as well as LCS is more likely by recent studies, a category of LC hyperplasia can be better characterized. LCH and LCS are rarely seen in daily pathology practice, but it is important to accurately characterize these lesions. For this purpose, an outline covering proliferations of LC and related cells was constructed. The scheme of this outline is based especially on evaluating borderline lesions, neoplastic trans-differentiation, and degree of similarity with the normal counter-parts. In addition, the organization and update of the current classification scheme for histiocytic and dendritic-cell proliferations is presented.
Adult T-cell leukaemia/lymphoma (ATLL) is a neoplasm originating in mature CD4+ peripheral T cells. However, rare cases of CD20+ ATLL have been reported. Here, we describe six cases of CD20+ ATLL diagnosed in our department. The median age was 79 years (range, 54–90 years); two patients were men, and four were women. Elevated lactate dehydrogenase was observed in four cases. All cases were lymphoma type and positive for human T-lymphotropic virus-1 (HTLV-1). HTLV-1 proviral DNA was detected in four cases. The Ann Arbor stage was I, II, or IV in one patient each and III in three patients. The clinical course was poor in almost all cases. Tumour cells were large in all cases, and flow cytometry revealed CD20+ lymphoma cells in five of six cases. Immunohistochemistry revealed lymphoma cells positive for CD20, CD3, CD4, and CCR4 and negative for CD8, CD79a, and PAX5 in all cases. CD20 expression was lower than that in normal B cells. One case was initially misdiagnosed as diffuse large B-cell lymphoma. Thus, combined use of an antibody panel and molecular genetic studies is important to avoid misdiagnosing ATLL as B-cell lymphoma.
Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) is a serious disorder in which monoclonal growth of T cells infected with EBV and macrophage activation cause pancytopenia, high fever and acute liver failure. Patients with chemotherapy- or immunosuppression-resistant EBV-HLH require allogeneic hematopoietic stem cell transplantation (allo-HSCT), but patients who have no sibling donors may not have time to wait for an unrelated donor. In pediatric patients, there are some reports on allogeneic cord blood transplantation (allo-CBT) for the treatment of EBV-HLH; however, in adult patients, reports of allo-CBT for EBV-HLH are quite limited. The present case of a 20-year-old woman with chemotherapy-resistant EBV-HLH and systemic lupus erythematosus (SLE) who underwent allo-CBT following reduced-intensity conditioning (RIC-CBT). She achieved and maintained a complete donor type and the EBV-DNA load, and the titers of anti-double stranded DNA and antinuclear antibodies became negative. It is therefore considered that RIC-CBT is an effective treatment option for adult onset HLH. However, because the effectiveness of allo-HSCT for SLE remains unclear and transplant-related mortality is high, it is recommended that allo-HSCT for SLE is restricted to patients concomitant with oncohematological disease as with our present case.