[Composite lymphoma: Case report of a coexisting follicular and mantle cell lymphoma in situ in a cervical node]

Composite lymphoma represents 1-4% of lymphomas. Only 8 case reports concerned coexisting follicular lymphoma and mantle cell lymphoma. Here, we report the case of an 81 years old man who has been diagnosed with a composite follicular and in situ mantle cell lymphoma. The use of a large panel of immunohistochemical stains associated with the flow cytometry results have allowed us to make this particular diagnosis. We highlight here a common clonal origin of the composite lymphoma's two entities, as described in previous publications.

Plasmacytoid dendritic cells proliferation associated with acute myeloid leukemia: phenotype profile and mutation landscape

Neoplasms involving plasmacytoid Dendritic Cells (pDCs) include Blastic pDC Neoplasms (BPDCN) and other pDC proliferations, where pDCs are associated with myeloid malignancies: most frequently Chronic MyeloMonocytic Leukemia (CMML) but also Acute Myeloid Leukemia (AML), hereafter named pDC-AML. We aimed to determine the reactive or neoplastic origin of pDCs in pDC-AML, and their link with the CD34+ blasts, monocytes or conventional DCs (cDCs) associated in the same sample, by phenotypic and molecular analyses (targeted NGS, 70 genes). We compared 15 pDC-AML at diagnosis with 21 BPDCN and 11 normal pDCs from healthy donors. CD45low CD34+ blasts were found in all cases (10-80% of medullar cells), associated with pDCs (4-36%), monocytes in 14 cases (1-10%) and cDCs (2 cases, 4.8-19%). pDCs in pDC-AML harbor a clearly different phenotype from BPDCN: CD4+ CD56- in 100% of cases, most frequently CD303+, CD304+ and CD34+; lower expression of cTCL1 and CD123 with isolated lymphoid markers (CD22/CD7/CD5) in some cases, suggesting a pre-pDC stage. In all cases, pDCs, monocytes and cDC are neoplastic since they harbor the same mutations as CD34+ blasts. RUNX1 is the most commonly mutated gene: detected in all AML with minimal differentiation (M0-AML) but not in the other cases. Despite low number of cases, the systematic association between M0-AML, RUNX1 mutations and an excess of pDC is puzzling. Further evaluation in a larger cohort is required to confirm RUNX1 mutations in pDC-AML with minimal differentiation and to investigate whether it represents a proliferation of blasts with macrophage and DC progenitor potential.

Standardization of Flow Cytometric Immunophenotyping for Hematological Malignancies: The FranceFlow Group Experience

Flow cytometry is broadly used for the identification, characterization, and monitoring of hematological malignancies. However, the use of clinical flow cytometry is restricted by its lack of reproducibility across multiple centers. Since 2006, the EuroFlow consortium has been developing a standardized procedure detailing the whole process from instrument settings to data analysis. The FranceFlow group was created in 2010 with the intention to educate participating centers in France about the standardized instrument setting protocol (SOP) developed by the EuroFlow consortium and to organise several rounds of quality controls (QCs) in order to evaluate the feasibility of its application and its results. Here, we report the 5 year experience of the FranceFlow group and the results of the seven QCs of 23 instruments, involving up to 19 centers, in France and in Belgium. The FranceFlow group demonstrates that both the distribution and applicability of the SOP have been successful. Intercenter reproducibility was evaluated using both normal and pathological blood samples. Coefficients of variation (CVs) across the centers were <7% for the percentages of cell subsets and <30% for the median fluorescence intensities (MFIs) of the markers tested. Intracenter reproducibility provided similar results with CVs of <3% for the percentages of the majority of cell subsets, and CVs of <20% for the MFI values for the majority of markers. Altogether, the FranceFlow group show that the 19 participating labs might be considered as one unique laboratory with 23 identical flow cytometers able to reproduce identical results. Therefore, SOP significantly improves reproducibility of clinical flow in hematology and opens new avenues by providing a robust companion diagnostic tool for clinical trials in hematology. © 2019 International Society for Advancement of Cytometry.

Increased frequencies of circulating and tumor-resident Vδ1+ T cells in patients with diffuse large B-cell lymphoma

Gamma-delta (γδ) T cells contribute to the innate immune response against cancer. In samples of 20 patients upon DLBCL diagnosis, we found that Vδ1⁺ T cells were the major γδ T cell subset in tumors and PBMCs of patients, while Vδ2 T cells were preponderant in PBMCs of healthy subjects. Interestingly, the germinal center (GC) subtype was associated with an increase in Vδ1⁺ T cells in tumors, whereas the non-GC subtype was associated with a lower frequency of γδ T cells. While circulating Vδ1⁺ T cells of patients or HSs mostly exhibited a naïve phenotype, the majority of tumor Vδ1⁺ T cells showed a central memory phenotype. Resident or circulating γδ T cells from patients were not functionally impaired since they produced high levels of IFN-γ. Collectively, our findings are in favor of γδ T cell activation in tumors and open new perspectives for their modulation in DLBCL immunotherapy.

[Cutaneous involvement in T-lymphoblastic lymphoma]

BACKGROUND

Lymphoblastic lymphoma (LBL) is a rare form of non-Hodgkin's lymphoma (NHL). Cutaneous LBL is seen in less than 20% of patients.

PATIENTS AND METHODS

Herein, we report the case of a 66-year-old male patient without any previous disease history of note and who was presenting a gradually spreading tumoral lesion of the scalp, several purplish macules and nodules on the trunk, and a single spinal adenopathy. A thoracic-abdominal-pelvic CT scan performed for acute renal failure, revealed extensive infiltration of retroperitoneal tissue. Skin biopsies and staging tests indicated LBL-T with associated cutaneous, bone and lymph node retroperitoneal lesions with no mediastinal mass. After two months of treatment with CHOP (four courses), the cutaneous lesions and abdominal tumoral mass had regressed and renal function had returned to normal.

DISCUSSION

There have been 13 reported cases of LBL with cutaneous involvement; most of these patients were young (under 30 years) and presented multiple cutaneous lesions (nodules or tumors) associated with numerous peripheral adenopathies, invasion of the bone marrow, and in many cases, a mediastinal mass. The clinical presentation of LBL-T in our case is novel on account of the cutaneous sites, associated with abdominal tumoral syndrome, without mediastinal infiltration, and with a single peripheral adenopathy, in an elderly subject.

Flow cytometry minimal residual disease after allogeneic transplant for chronic lymphocytic leukemia

OBJECTIVES

This study investigates whether achieving complete remission (CR) with undetectable minimal residual disease (MRD) after allogeneic stem cell transplantation (allo-SCT) for chronic lymphocytic leukemia (CLL) affects outcome.

METHODS

We retrospectively studied 46 patients transplanted for CLL and evaluated for post-transplant MRD by flow cytometry.

RESULTS

At transplant time, 43% of the patients were in CR, including one with undetectable MRD, 46% were in partial response, and 11% had refractory disease. After transplant, 61% of the patients achieved CR with undetectable MRD status. By multivariate analysis, reaching CR with undetectable MRD 12 months after transplant was the only factor associated with better progression-free survival (P = 0.02) and attaining undetectable MRD, independently of the time of negativity, was the only factor that correlated with better overall survival (P = 0.04).

CONCLUSION

Thus, achieving undetectable MRD status after allo-SCT for CLL is a major goal to improve post-transplant outcome.

The prognostic value of hematogones in patients with acute myeloid leukemia

In acute myeloid leukemia (AML), new prognostic tools are needed to assess the risk of relapse. Hematogones (HGs) are normal B-lymphocyte precursors that increase in hematological diseases and may influence remission duration in AML. HG detection was prospectively investigated in 262 AML patients to determine its prognostic value. Flow cytometric HG detection was performed in bone marrow aspiration after intensive chemotherapy at the time of hematological recovery. Patients with HGs in bone marrow samples had a significantly better relapse-free survival (RFS) and overall survival (OS) than patients without HGs (P = 0.0021, and P = 0.0016). Detectable HGs independently predicted RFS (HR = 0.61, 95%CI: 0.42 - 0.89, P = 0.012) and OS (HR = 0.59, 95%CI: 0.38 - 0.92, 0.019) controlling for age, ELN classification, the number of chemotherapy cycles to achieve CR, performance status, secondary AML and flow cytometric minimal residual disease (MRD). In intensively treated AML, individual determination of HGs could be useful to stratify the optimal risk-adapted therapeutic strategy after induction chemotherapy. Am. J. Hematol. 91:566-570, 2016. © 2016 Wiley Periodicals, Inc.

Vasculitis associated with large granular lymphocyte (LGL) leukemia: presentation and treatment outcomes of 11 cases

OBJECTIVE

The association between vasculitis and large granular lymphocyte (LGL) leukemia has rarely been reported or investigated. Thus, we assessed the clinical and biological phenotypes of LGL leukemia associated with vasculitis.

RESULTS

We studied a series of 11 patients displaying LGL leukemia associated with vasculitis (LAV). The mean age at diagnosis of LGL leukemia was 60.3 years; there were nine women and two men. The mean follow-up period was 45 months. The main LGL lineage was T-LGL (10 patients), and only one NK-LGL was identified. Clinical and biological features of T-LGL leukemia were compared with those from the 2009 French T-LGL registry. We did not find any relevant differences except that patients with LAV were predominantly female (p < 0.05). The most frequently observed vasculitis was cryoglobulinemia (n = 5). Three patients presented with cutaneous leukocytoclastic angiitis, two patients had ANCA-negative microscopic polyangiitis, and one patient had giant cell arteritis. The main clinical features involved the skin, e.g., purpura (91%), arthralgia (37%), peripheral neuritis (27%), and renal glomerulonephritis (18%). The most frequent histologic finding was leucocytoclastic vasculitis (54%). The rate of complete remission was high; i.e., 80%. A minority of patients had a vasculitis relapse (27%). Three patients (27%) died; one death was related to LGL leukemia (acute infection) and the two other deaths were related to vasculitis (both with heart failure).

CONCLUSION

We conclude that vasculitis is overrepresented in the population of LGL patients, LAV predominantly affects women, vasculitis preferentially affects the small vessels, and LAV has high rate of complete response.

Deciphering leukemic B-cell chronic lymphoproliferative disorders

Diagnosis of leukemic B-cell chronic lymphoproliferative disorders (B-CLPD) is a frequent challenge in hematology. In this multicentric study, we prospectively studied 165 new consecutive leukemic patients with B-CLPD selected on the basis of Royal Marsden Hospital scoring system < or =3. The primary aim of the study was to try to decipher the atypical cases and identify homogenous subgroups. Overall, morphological examination contributed to diagnosis in only 20% cases, all of them CD5 negative. Thirty additional cases were CD5 negative suggestive of leukemic marginal zone lymphoma in most cases. The significantly poorer survival of the 26 cyclin D1 positive cases justifies recommending its systematic determination among atypical B-CLPD. CD20 expression segregated clearly two subgroups among CD5 positive cyclin D1 negative B-CLPD. The 17 patients with the CD20 dim profile represent a homogeneous subgroup very close to typical B-cell chronic lymphocytic leukemia (B-CLL) on morphological, phenotypical and cytogenetical criteria. In contrast, the subgroup of 51 patients with a CD20 bright profile is heterogeneous. Their significantly lower p27 expression level suggest the presence of a proliferative component, underlying a more aggressive disease. Further genomic studies are warranted to establish their precise nature. These cases should not be included in the same therapeutic trials as B-CLL.

Extended diagnostic criteria for plasmacytoid dendritic cell leukaemia

The diagnosis of plasmacytoid dendritic cell leukaemia (pDCL) is based on the immunophenotypic profile: CD4(+) CD56(+) lineage(neg) CD45RA(+)/RO(neg) CD11c(neg) CD116(low) CD123(+) CD34(neg) CD36(+) HLA-DR(+). Several studies have reported pDCL cases that do not express this exact profile or expressing some lineage antigens that could thus be misdiagnosed. This study aimed to validate pDCL-specific markers for diagnosis by flow-cytometry or quantitative reverse transcription polymerase chain reaction on bone marrow samples. Expression of markers previously found in normal pDC was analysed in 16 pDCL, four pDCL presenting an atypical phenotype (apDCL) and 113 non-pDC - lymphoid or myeloid - acute leukaemia. CD123 was expressed at significantly higher levels in pDCL and apDCL. BDCA-2 was expressed on 12/16 pDCL and on 2/4 apDCL, but was never detected in the 113 non-pDC acute leukaemia cases. BDCA-4 expression was found on 13/16 pDCL, but also in 12% of non-pDC acute leukaemia. High levels of LILRA4 and TCL1A transcripts distinguished pDCL and apDCL from all other acute leukaemia (except B-cell acute lymphoblastic leukaemia for TCL1A). We thus propose a diagnosis strategy, scoring first the CD4(+) CD56(+/-) MPO(neg) cCD3(neg) cCD79a(neg) CD11c(neg) profile and then the CD123(high), BDCA-2 and BDCA-4 expression. Atypical pDCL can be also identified this way and non-pDC acute leukaemia excluded: this scoring strategy is useful for diagnosing pDCL and apDCL.

Expression of the myeloid-associated marker CD33 is not an exclusive factor for leukemic plasmacytoid dendritic cells

A new entity of acute leukemia coexpressing CD4(+)CD56(+) markers without any other lineage-specific markers has been identified recently as arising from lymphoid-related plasmacytoid dendritic cells (pDCs). In our laboratory, cells from a patient with such CD4(+)CD56(+) lineage-negative leukemia were unexpectedly found to also express the myeloid marker CD33. To confirm the diagnosis of pDC leukemia despite the CD33 expression, we demonstrated that the leukemic cells indeed exhibited pDC phenotypic and functional properties. In 7 of 8 other patients with CD4(+)CD56(+) pDC malignancies, we were able to confirm that the tumor cells expressed CD33 although with variable expression levels. CD33 expression was shown by flow cytometry, reverse transcriptase-polymerase chain reaction, and immunoblot analysis. Furthermore, CD33 monoclonal antibody stimulation of purified CD4(+)CD56(+) leukemic cells led to cytokine secretion, thus confirming the presence of a functional CD33 on these leukemic cells. Moreover, we found that circulating pDCs in healthy individuals also weakly express CD33. Overall, our results demonstrate that the expression of CD33 on CD4(+)CD56(+) lineage-negative cells should not exclude the diagnosis of pDC leukemia and underline that pDC-specific markers should be used at diagnosis for CD4(+)CD56(+) malignancies.

Leukemic plasmacytoid dendritic cells share phenotypic and functional features with their normal counterparts

This work aims to further characterize the newly described leukemic plasmacytoid dendritic cells (LPDC), for which we had previously demonstrated their normal, PDC-like ability to produce IFN-alpha. In addition, LPDC also express the specific antigens BDCA-2 and BDCA-4. Importantly, they become fully competent antigen-presenting cells (APC) after a short maturation induced by IL-3 + CD40L or virus, exhibiting a characteristic APC phenotype (high expression of CD83 and of the costimulatory molecules CD40, CD80, CD86). Whereas IL-3 + CD40L-activated LPDC prime naive CD4(+) T cells towards a Th2 pathway (IL-4-secreting T cells), virus-activated LPDC drive a Th1 profile (IFN-gamma-secreting T cells). Moreover, we show in one case that LPDC are able to capture, process and present exogenous antigens, leading to the activation of both CD4(+) and CD8(+) T cell clones in an antigen-specific manner. This study further characterizes the phenotype and immunological functions of LPDC.

Skin manifestations in CD4+, CD56+ malignancies

CD4+ CD56+ hematologic neoplasms were recently individualized. We report three cases of CD4+ CD56+ malignancies with cutaneous lesions in three cases and also bone marrow involvement in two cases. Two patients relapsed 2 and 3 months after polychemotherapy. Two patients died within 3-10 months. A constant immunophenotype was observed with the co-expression of CD4 and CD56, the absence of B and T-cell markers. The salient fact of this report is the presence of T-cell clonal rearrangement. The clinical and pathological features closely resemble the specific cutaneous manifestations in acute leukemia with monocytic differentiation, especially the granulocytic sarcoma. Because of the positivity of the CD56, natural killer cell proliferations were discussed. Since 1994, 50 cases of CD4+, CD56+ cutaneous neoplasms have been reported with specific clinical, cytologic and immunohistochemical features. The diagnosis is more difficult when the cutaneous location is exclusive; on the contrary, the cytological features of the blood and medullar cells with cytoplasmic vacuoles and pseudopodia are characteristic of this hematologic neoplasm. The presence of CD123 antigen in most of the cases is an argument for a plasmacytoid dendritic cell proliferation and it is also a good marker for primary cutaneous lesions.