B-cell lymphomas with discordance between pathological features and clinical behavior

B-cell lymphomas encompass a large number of disease entities clinically ranging from indolent to aggressive. The defining pathological features usually predict clinical course, with small and large B-cell lymphomas correlating to low-grade vs high-grade features, but discordant situations may be encountered. Two sessions of the workshop of the XVIII meeting of the European Association for Haematopathology (EAHP) held in Basel in 2016 addressed this topic. One session illustrated various facets of "aggressiveness" in indolent lymphomas, either peculiar clinical manifestations, cytological variants, or unusual genetic features, as well as several examples of progression or transformation to a more aggressive disease. Another session exemplified large B-cell lymphomas with unexpected indolent behavior including cases arising in well-defined body compartments or in sanctuary sites. This paper describes the features of the cases presented in both groups, highlights the most salient points of discussion raised by the submitters and the panel, and summarizes current knowledge and recommendations relevant to diagnostic pathology practice

Chlorambucil versus observation after anti-Helicobacter therapy in gastric MALT lymphomas: results of the international randomised LY03 trial

Gastric mucosa-associated lymphoid tissue (MALT) lymphomas are uncommon tumours characterised by a tendency to remain localised for long periods. The aetiological association between MALT lymphomas and Helicobacter pylori is well established. The role of additional chemotherapy after H. pylori eradication in localised MALT lymphomas is unclear. The LY03 trial was designed to establish whether chlorambucil after treatment for H. pylori would help prevent recurrence. Patients were treated with antibiotics for H. pylori infection. Those with successful eradication of H. pylori and no evidence of progression of lymphoma were eligible for randomisation to chlorambucil or observation. Two hundred and thirty-one patients were registered. Ninety-seven percent patients had H. pylori eradicated after antibiotics and 59% achieved macroscopically normal gastric mucosa. One hundred and ten patients were randomised. With a median follow-up of 58 months, six patients were dead and 17 had recurrent/progressive disease. The recurrence/progression rates at 5 years were 11% for chlorambucil, and 21% for observation with a difference of 10%, 95% confidence interval (CI) = −9% to 29%, P = 0·15. No difference was detected in recurrence/progression-free survival [Hazard Ratio (HR) = 0·96, 95% CI = 0·41–2·2, P = 0·91] or overall survival (HR = 1·93, 95% CI = 0·39–9·58, P = 0·42). This is the first randomised trial to show there is no good evidence to support that additional single agent chemotherapy to anti-H. pylori treatment contributes to prevent recurrence in localised gastric MALT lymphomas

Diffuse large B-cell lymphoma of Waldeyer's ring has distinct clinicopathologic features: a GELA study

Background Diffuse large B-cell lymphomas (DLBCLs) arising in specific extranodal sites have peculiar clinicopathologic features. Patients and methods We analyzed a cohort of 187 primary Waldeyer's ring (WR) DLBCLs retrieved from GELA protocols using anthracyclin-based polychemotherapy. Results Most patients (92%) had stage I-II disease. A germinal center B-cell-like (GCB) immunophenotype was observed in 61%, and BCL2 expression in 55%, of WR DLBCLs. BCL2, BCL6, IRF4 and MYC breakpoints were observed in, respectively, 3 of 42 (7%), 9 of 36 (25%), 2 of 26 (8%) and 4 of 40 (10%) contributive cases. A variable follicular pattern was evidenced in 30 of 68 (44%) large biopsy specimens. The 5-year progression-free survival (PFS) and the overall survival (OS) of 153 WR DLBCL patients with survival information were 69.5% and 77.8%, respectively. The GCB immunophenotype correlated with a better OS (P=0.0015), while BCL2 expression predicted a worse OS (P=0.037), an effect overcome by the GCB/non-GCB classification. Compared with matched nodal DLBCLs, WR DLBCLs with no age-adjusted international prognostic index factor disclosed a better 5-year PFS rate (77.5% versus 70.7%; P=0.03). Conclusions WR DLBCLs display distinct clinicopathologic features compared with conventional DLBCLs, with usual localized-stage disease, common follicular features and a high frequency of GCB immunophenotype contrasting with a low rate of BCL2 rearrangements. In addition, they seem to be associated with a better outcome than their nodal counterpar

The prognosis of MYC translocation positive diffuse large B-cell lymphoma depends on the second hit.

A proportion of MYC translocation positive diffuse large B-cell lymphomas (DLBCL) harbour a BCL2 and/or BCL6 translocation, known as double-hit DLBCL, and are clinically aggressive. It is unknown whether there are other genetic abnormalities that cooperate with MYC translocation and form double-hit DLBCL, and whether there is a difference in clinical outcome between the double-hit DLBCL and those with an isolated MYC translocation. We investigated TP53 gene mutations along with BCL2 and BCL6 translocations in a total of 234 cases of DLBCL, including 81 with MYC translocation. TP53 mutations were investigated by PCR and sequencing, while BCL2 and BCL6 translocation was studied by interphase fluorescence in situ hybridization. The majority of MYC translocation positive DLBCLs (60/81 = 74%) had at least one additional genetic hit. In MYC translocation positive DLBCL treated by R-CHOP (n = 67), TP53 mutation and BCL2, but not BCL6 translocation had an adverse effect on patient overall survival. In comparison with DLBCL with an isolated MYC translocation, cases with MYC/TP53 double-hits had the worst overall survival, followed by those with MYC/BCL2 double-hits. In MYC translocation negative DLBCL treated by R-CHOP (n = 101), TP53 mutation, BCL2 and BCL6 translocation had no impact on patient survival. The prognosis of MYC translocation positive DLBCL critically depends on the second hit, with TP53 mutations and BCL2 translocation contributing to an adverse prognosis. It is pivotal to investigate both TP53 mutations and BCL2 translocations in MYC translocation positive DLBCL, and to distinguish double-hit DLBCLs from those with an isolated MYC translocation.The authors would like to thank Dr. Ian McFarlane, the Microarray CoreLab, David Withers, IMS Metabolic Research Laboratories, National Institute of Health Research, Cambridge Comprehensive Biomedical Research Centre for their help in DNA sequencing. We also thank Dr. Ramesh Bulusu, Dr. Kanchan Regge, Dr. Muttuswamy Sivakumaran, Dr. Sateesh Nagumantry, Dr. Andrew Hodson, Dr. Mamtha Karanth, Dr. Sandra Young-Min, Dr. Jane Keidan, and Dr. Martin Lewis for providing clinical data. The research in MQD lab was supported by grants from Leukaemia & Lymphoma Research, U.K. Kay Kendall Leukaemia Fund (KKLF), The Pathological Society of UK & Ireland, and the Addenbrooke’s Charitable Trust (ACT). NG was supported by a KKLF and an ACT fellowship. Research in JG's lab was funded by Tenovus Tayside; JB was supported by a research grant from the Paul Abrahams Fund.This is the final version of the article. It was first published by Wiley at http://doi.org/10.1002/cjp2.1

Primary mediastinal B-cell lymphoma: detection of BCL2 gene rearrangements by PCR analysis and FISH

Primary mediastinal large B-cell lymphoma (PMBCL) has a characteristic clinical presentation, morphology, and immunophenotype, representing a clinically favorable subgroup of diffuse large B-cell lymphoma (DLBCL). By gene expression profiling (GEP), PMBCL shares features with classical Hodgkin lymphoma (cHL). Of further interest, BCL6 gene mutations and BCL6 and/or MUM1 expression in a number of PMBCLs have supported an activated B-cell (ABC) origin. Several studies, including GEP, have failed to detect BCL2 gene rearrangements (GRs) in PMBCL. An index case of t(14; 18)+ PMBCL prompted our study of the incidence of BCL2 GRs in PMBCL by polymerase chain reaction (PCR)/fluorescence in situ hybridization (FISH) analyses and its possible clinical impact. Twenty-five retrospectively identified, well-defined PMBCLs (five with cytogenetics) from three institutions were analyzed for a BCL2 GR by PCR/FISH analyses. The formalin-fixed, paraffin-embedded tissue blocks of 24 available cases were also analyzed by BCL2 immunohistochemistry (IHC). Of the five with cytogenetics, two had a t(14; 18) (q32; q21). Of the 25 analyzed by PCR, 2 had no amplifiable DNA (aDNA), including 1 t(14; 18)+ case. Of those with aDNA, two showed a BCL2 GR; by FISH analysis, three demonstrated a BCL2 GR. BCL2 protein expression by IHC analysis was variably detected in 21 out of 24 (strongly, uniformly expressed: 6, including all with a t(14; 18) or a BCL2 gene rearrangement; moderately weakly expressed in a subset of the malignant cells: 15). Available clinical follow-up of this BCL2+ subset showed a similar course to the other PMBCL cases. Our results imply that a subset of PMBCL [(4 out of 24 analyzed) in our series] may be of GC origin. A larger study is necessary to determine any clinical significance

Translocation detection in lymphoma diagnosis by split-signal FISH: a standardised approach

Lymphomas originating from the lymphatic system comprise about 30 entities classified according to the World Health Organization (WHO). The histopathological diagnosis is generally considered difficult and prone to mistakes. Since non-random chromosomal translocations are specifically involved in different lymphoma entities, their detection will be increasingly important. Hence, a split-signal fluorescence in situ hybridisation (FISH) procedure would be helpful in discriminating the most difficult classifications. The Euro-FISH programme, a concerted action of nine European laboratories, has validated a robust, standardised protocol to improve the diagnostic approach on lymphoma entities. Therefore, 16 fluorescent probes and 10 WHO entities, supplemented with reactive cases, were selected. The results of the Euro-FISH programme show that all probes were correctly cytogenetically located, that the standardised protocol is robust, resulting in reliable results in approximately 90% of cases, and that the procedure could be implemented in every laboratory, bringing the relatively easy interpretation of split-signal probes within the reach of many pathology laboratories

Gray zones around diffuse large B cell lymphoma. Conclusions based on the workshop of the XIV meeting of the European Association for Hematopathology and the Society of Hematopathology in Bordeaux, France

The term “gray-zone” lymphoma has been used to denote a group of lymphomas with overlapping histological, biological, and clinical features between various types of lymphomas. It has been used in the context of Hodgkin lymphomas (HL) and non-Hodgkin lymphomas (NHL), including classical HL (CHL), and primary mediastinal large B cell lymphoma, cases with overlapping features between nodular lymphocyte predominant Hodgkin lymphoma and T-cell/histiocyte-rich large B cell lymphoma, CHL, and Epstein–Barr-virus-positive lymphoproliferative disorders, and peripheral T cell lymphomas simulating CHL. A second group of gray-zone lymphomas includes B cell NHL with intermediate features between diffuse large B cell lymphoma and classical Burkitt lymphoma. In order to review controversial issues in gray-zone lymphomas, a joint Workshop of the European Association for Hematopathology and the Society for Hematopathology was held in Bordeaux, France, in September 2008. The panel members reviewed and discussed 145 submitted cases and reached consensus diagnoses. This Workshop summary is focused on the most controversial aspects of gray-zone lymphomas and describes the panel’s proposals regarding diagnostic criteria, terminology, and new prognostic and diagnostic parameters