Darius Juskevicius

Follicular lymphoma transformation into histiocytic sarcoma: indications for a common neoplastic progenitor

Follicular lymphoma transformation into histiocytic sarcoma: indications for a common neoplastic progenitor

Distinct genetic evolution patterns of relapsing diffuse large B-cell lymphoma revealed by genome-wide copy number aberration and targeted sequencing analysis.

Recurrences of diffuse large B-cell lymphomas (DLBCL) result in significant morbidity and mortality, but their underlying genetic and biological mechanisms are unclear. Clonal relationship in DLBCL relapses so far is mostly addressed by the investigation of immunoglobulin (IG) rearrangements, therefore, lacking deeper insights into genome-wide lymphoma evolution. We studied mutations and copy number aberrations in 20 paired relapsing and 20 non-relapsing DLBCL cases aiming to test the clonal relationship between primaries and relapses to track tumors’ genetic evolution and to investigate the genetic background of DLBCL recurrence. Three clonally unrelated DLBCL relapses were identified (15%). Also, two distinct patterns of genetic evolution in clonally related relapses were detected as follows: (1) early-divergent/branching evolution from a common progenitor in 6 patients (30%), and (2) late-divergent/linear progression of relapses in 11 patients (65%). Analysis of recurrent genetic events identified potential early drivers of lymphomagenesis (KMT2D, MYD88, CD79B and PIM1). The most frequent relapse-specific events were additional mutations in KMT2D and alterations of MEF2B. SOCS1 mutations were exclusive to non-relapsing DLBCL, whereas primaries of relapsing DLBCL more commonly displayed gains of 10p15.3–p12.1 containing the potential oncogenes PRKCQ, GATA3, MLLT10 and ABI1. Altogether, our study expands the knowledge on clonal relationship, genetic evolution and mutational basis of DLBCL relapses.

Clinical, morphologic, phenotypic, and genetic evidence of cyclin D1-positive diffuse large B-cell lymphomas with CYCLIN D1 gene rearrangements.

Overexpression of cyclin D1 in diffuse large B-cell lymphomas (DLBCLs) is observable in about 5% of cases and is linked to gains of additional CYCLIN D1 gene copies or deregulation at the mRNA level. All cyclin D1-positive DLBCL cases reported so far lack the canonical t(11;14)(q13;q32) translocation that is a genetic hallmark and the primary cause of cyclin D1 overexpression in mantle cell lymphoma (MCL). Using standard histologic and genetic techniques, complemented with genome-wide aberration analysis by array comparative genomic hybridization, we characterized 2 exceptional cases of blastoid B-cell lymphomas with cyclin D1 overexpression, both bearing genetic rearrangements in the CYCLIN D1 gene locus. One of them had a t(11;14)(q13;q32) translocation and featured morphology, immunophenotype, and genetic copy number aberrations typical of DLBCL. The second case had a complex t(4;11;14) translocation, but the other features were intermediate between DLBCL and MCL and did not allow unambiguous classification in any of the current diagnostic lymphoma categories. On the basis of these findings, we conclude that detection of t(11;14) should not preclude a diagnosis of cyclin D1-positive DLBCL when all other parameters are in agreement with such a diagnosis. Moreover, a yet unacknowledged diagnostic “gray zone” may exist between DLBCL and MCL.

Diagnostic Utility of the Germinal Center-associated Markers GCET1, HGAL, and LMO2 in Hematolymphoid Neoplasms.

Implementation of new phenotypic markers in routine diagnostics of hematolymphoid neoplasms is a challenging task with a plethora of potentially relevant proteins. We investigated 3 recently discovered proteins expressed in the germinal centers of lymph nodes (LMO2, GCET1, and HGAL) in a compilation of leukemia, lymphoma, and thymic tumor entities. Altogether, 1590 cases (1519 on tissue microarrays, 71 on conventional slides) were included. Expressions of LMO2, GCET1, and HGAL were investigated by immunohistochemistry, evaluated for their differential diagnostic relevance, and correlated with the clinical outcome of patients. In Hodgkin lymphoma (HL), the expression of LMO2, GCET1, and HGAL could be largely seen in tumor cells of nodular lymphocyte predominant HL (NLPHL) but only occasionally in classic HL. The majority of B-cell lymphoma cases was positive for LMO2 [except for Burkitt lymphoma (BL)] and HGAL with weaker to moderate staining intensity, compared with the intensely staining follicular lymphomas (FL). Except for FL (60% of cases) and diffuse large B-cell lymphomas (DLBCL, 36% of cases), all other B-cell lymphomas expressed little or no GCET1. In thymomas, the non-neoplastic immature T-cells were LMO2-negative, whereas the neoplastic lymphoblasts were LMO2-positive in more than half of the lymphoblastic lymphomas (LBL). Our findings provide new potential assistance in the differential diagnosis of FL to marginal zone lymphoma, classic HL to NLPHL and primary mediastinal B-cell lymphoma, DLBCL to BL, and thymoma to LBL. Finally, HGAL proved to be a prognostic marker for classic HL regarding the background population and in DLBCL regarding the tumor cells.

Is Rosai-Dorfman disease a reactve process? Detection of a MAP2K1 L115V mutation in a case of Rosai-Dorfman disease

Histiocytoses are rare disorders characterized by the accumulation of macrophages, dendritic cells, or monocyte-derived cells in various tissues and organs of children and adults [1]. In principle, histiocytic disorders can be subdivided into three groups: Langerhans cell (LC), non-LC and malignant histiocytoses (MH). Recently, a more detailed subdivision has been proposed [1], which defined five subgroups, of which one was dedicated to Rosai-Dorfman disease (RDD). RDD is a non-LC histiocytosis, which has been described as a distinct clinico-pathological entity almost 50 years ago [2]. Its etiology is still unknown but it is considered as reactive with a benign clinical course, particularly if involving solely lymph nodes [3].Most cases occur idiopathic but some are associated with other disorders like IgG4-related diseases, the autoimmune lymphoproliferative syndrome or various autoimmune and hereditary conditions [3]. Patients present typically with a massive bilateral cervical lymphadenopathy accompanied by fever, night sweats, fatigue, and weight loss [1, 2]. RDD can also be observed at several extranodal sites, such as the skin and soft tissues, the nasal cavity, the bones, and the central nervous system. Thus, RDD is a heterogeneous entity, and it is recommended to distinguish classical cases with exclusive single or regional lymph node involvement from extranodal cases [1]. Morphological examination of the affected tissues, accompanied by immunohistochemistry is the basis for RDD diagnosis. Large histiocytic cells with hypochromatic roundish nuclei and pale cytoplasm are present and show abundant emperipolesis of lymphocytes, plasma cells, and erythrocytes. Immunohistochemically, RDD histiocytes stain positively for S100, CD68, and CD163. In contrast, CD1a and/or CD207 (Langerin) are negative. Involved tissues usually contain abundant polyclonal, more often IgG4+ plasma cells, activated B cells and an increased amount of fibers. Laboratory abnormalities in RDD are non-specific with elevated erythrocyte sedimentation rate and leukocytosis, high ferritin, hypergammaglobulinemia, and autoimmune hemolytic anemia. Recently, several studies have revealed recurrent mutations in histiocytoses. In particular, the BRAF V600E mutation has been described in Langerhans cell histiocytosis (LCH) and Erdheim-Chester disease (ECD) [4, 5]. Further genetic aberrations in LCH and ECD include mutations of MAP2K1 [6], as wells asNRAS, KRAS, and PIK3CA in ECD [5]. In contrast, mutations in RDD seem to be a rare event and have been described in KRAS, SMAD4 and MAP2K1 [5, 7]. Here we report a case of an extranodal RDD in the buttocks of a 71year-old male patient with a previously unreported MAP2K1 L115V mutation.

Extracavitary primary effusion lymphoma: clinical, morphological, phenotypic and cytogenetic characterization using nuclei enrichment technique

Primary effusion lymphoma (PEL) is a rare form of aggressive B‐cell lymphoma, which typically manifests as malignant effusion in the body cavities. However, extracavitary solid variants are also described. The aim of this study was to investigate copy number aberrations in two cases of solid PEL at their first occurrences and relapse by applying a newly developed methodology of tumour nuclei enrichment.

Mutational landscape of B-cell post-transplant lymphoproliferative disorders

It is currently unclear whether post‐transplant diffuse large B‐cell lymphomas (PT‐DLBCL) display a similar genomic landscape as DLBCL in immunocompetent patients (IC‐DLBCL). We investigated 50 post‐transplant lymphoproliferative disorders (PTLDs) including 37 PT‐DLBCL samples for somatic mutations frequently observed in IC‐DLBCL. Targeted Next Generation Sequencing (NGS) using the Ion Torrent platform and a customized panel of 68 genes was performed on genomic DNA. Non‐tumoural tissue was sequenced to exclude germline variants in cases where available. A control cohort of 76 IC‐DLBCL was available for comparative analyses. In comparison to IC‐DLBCLs, PT‐DLBCL showed more frequent mutations of TP53 (P = 0·004), and absence of ATM and B2M mutations (P = 0·004 and P = 0·016, respectively). In comparison to IC‐DLBCLs, Epstein–Barr virus (EBV)+ PT‐DLBCL had fewer mutated genes (P = 0·007) and particularly fewer mutations in nuclear factor‐κB pathway‐related genes (P = 0·044). TP53 mutations were more frequent in EBV‐ PT‐DLBCL as compared to IC‐DLBCL (P = 0·001). Germinal centre B cell (GCB) subtype of PT‐DLBCL had fewer mutations and mutated genes than GCB‐IC‐DLBCLs (P = 0·048 and 0·04 respectively). Polymorphic PTLD displayed fewer mutations as compared to PT‐DLBCL (P = 0·001). PT‐DLBCL differs from IC‐DLBCL with respect to mutations in genes related to DNA damage control and immune‐surveillance, and EBV association is likely to have a bearing on the mutational pattern.

Sharing of a PTPN11 mutation by myelodysplastic bone marrow and a mature plasmacytoid dendritic cell proliferation provides evidence for their common myelomonocytic origin

Plasmacytoid dendritic cells (PDC) represent a subset of dendritic cells with unique morphology, function and cell surface phenotype [1]. They originate in the bone marrow from myeloid cell progenitors. PDC home in lymph nodes and are typically located close to high endothelial venules in small clusters. The presence of a significant number of PDC in lymph nodes indicates an ongoing immune reaction [2]. In other lymphoid tissues and in the bone marrow, PDC usually do not form aggregates but are scattered. PDC have been reported to give rise to two types of neoplasm [3]: a proliferation of mature PDC associated with a myeloid neoplasm, which most likely constitute a divergent form of differentiation of the malignant myelo-monocytic clone, and a blastic PDCneoplasm arising fromTdT+CD4+CD56+PDCprecursor cells.Mature PDC proliferations associatedwith amyeloid neoplasm aremost often encountered in chronicmyelomonocytic leukemia or, less often, in myelodysplastic syndromes (MDS) or acute leukemia with monocytic differentiation as to be expected from their putative divergent evolution form a putative malignant myelo-monocytic clone [4]. They are rare and occur predominantly (75%) in male patients with a median age of 69 years. Clinically, patients present with lymphadenopathy and skin lesions and, rarely, splenomegaly. Histopathologically, such proliferations are characterized by nodular, sometimes confluent, aggregates of clonally expanded mature PDC. Treatment of the underlying myeloid neoplasm may result in regression of the PDC component [5, 6]. Prognosis is usually poor, mainly due to the evolution of the myeloid neoplasm rather than expansion of PDC. The genomic landscape of such mature PDC proliferations is poorly understood. Several studies suggest a clonal relationship between the PDC and the associated myeloid neoplasm [7]. A unifying molecular pathway in terms of recurrent genomic aberrations has not yet been identified. We report a case of mature PDC proliferation associated with MDS with multilineage dysplasia (MDS-MLD according to the updated fourth edition of the WHO classification; refractory cytopenia with multilineage dysplasia (RCMD) according to the WHO 2008 classification). A clonal relationship of the PDC and the myeloid components was proven by a shared PTPN11 (protein tyrosine phosphatase, non-receptor type 11) mutation. Furthermore, using massive parallel sequencing (NGS) and array comparative genomic hybridization (aCGH), we document the genomic evolution in time of the myeloid component and the genomic stability of the PDC component.

Comprehensive phenotypic characterization of PTLD reveals potential reliance on EBV or NF‐κB signalling instead of B‐cell receptor signalling

Post‐transplant lymphoproliferative disorders (PTLD) are a major problem in transplant medicine. So far, the insights into pathogenesis and potentially druggable pathways in PTLD remain scarce. We investigated a cohort of PTLD patients, consisting of both polymorphic (n = 3) and monomorphic (n = 19) B‐cell lymphoproliferations. Several signalling pathways, cell of origin of PTLD and their relation to viruses were analysed by immunohistochemistry and in situ hybridization. Most PTLD were of activated B‐cell origin. Two‐thirds of cases showed an Epstein–Barr virus (EBV) infection of the neoplastic cells. NF‐κB signalling components were present in the majority of cases, except for EBV‐infected cases with latency type III lacking CD19 and upstream B‐cell signalling constituents. Proteins involved in B‐cell receptor signalling like Bruton tyrosine kinase were only present in a minority of cases. Phosphoinositide 3‐kinase (PI3K) was expressed in 94% of cases and the druggable PI3K class 1 catalytic subunit p110 in 76%, while proteins of other signalling transduction pathways were expressed only in single cases. Unsupervised cluster analysis revealed three distinct subgroups: (i) related to EBV infection, mainly latency type III and mostly lacking CD19, upstream B‐cell signalling and NF‐κB constituents; (ii) mostly related to EBV infection with expression of the alternative NF‐κB pathway compound RelB, CD10, and FOXP1 or MUM1; and finally, (iii) mostly unrelated to virus infection with expression of the classic NF‐κB pathway compound p65. EBV and NF‐κB are important drivers in PTLD in contrast to B‐cell receptor signalling. The main signal transduction pathway is related to PI3K. This links PTLD to other subgroups of EBV‐related lymphomas, highlighting also new potential treatment approaches. Copyright

Lenalidomide monotherapy leads to a complete remission in refractory B-cell post-transplant lymphoproliferative disorder

Heinz Läubli, Alexandar Tzankov, Darius Juskevicius, Lukas Degen, Christoph Rochlitz & Frank Stenner-Liewen Department of Internal Medicine, Division of Medical Oncology, University Hospital Basel, Switzerland, Department of Biomedicine, Cancer Immunology Laboratory, University Hospital Basel, Switzerland, Institute of Pathology, University Hospital Basel, Switzerland, and Division of Gastroenterology and Hepatology, University Hospital Basel, Switzerland