Georges Delsol

Tumours of histiocytes and accessory dendritic cells: An immunohistochemical approach to classification from the International Lymphoma Study Group based on 61 cases

Tumours of histiocytes and accessory dendritic cells: an immunohistochemical approach to classification from the International Lymphoma Study Group based on 61 cases

Origin of Nodular Lymphocyte-Predominant Hodgkin's Disease from a Clonal Expansion of Highly Mutated Germinal-Center B Cells

BACKGROUND The atypical cells of nodular lymphocyte-predominant Hodgkins disease, designated lymphocytic and histiocytic (L&H) cells, have a B-cell phenotype. To clarify the clonality of these cells, we studied rearranged immunoglobulin genes for the variable region of the heavy chain (V[H] genes) in individual L&H cells from 11 patients with nodular lymphocyte-predominant Hodgkins disease. We also studied the expression of immunoglobulin light chains by those cells in six of the same patients. METHODS Single CD20+ L&H cells were isolated from frozen sections by a technique of micromanipulation. The rearranged V(H) genes of these cells were amplified by the polymerase chain reaction (PCR), sequenced, and compared with germ-line V(H) genes. Immunoglobulin light-chain messenger RNA (mRNA) was detected by in situ hybridization. RESULTS Of 615 L&H cells isolated from all the frozen sections, 160 yielded PCR products. In each of the 11 patients, the L&H cells that could be evaluated had identically rearranged V(H) genes, whether they were isolated from the same nodule, different nodules, or different blocks of tissue. All the V(H) sequences derived from the L&H cells were highly mutated (7.5 to 27.2 percent). In two cases the coding capacity of the V(H) genes was completely or partially disrupted by mutations. Intraclonal diversity was found in six cases, and monotypic immunoglobulin light-chain mRNA was found in six. CONCLUSIONS The L&H cells of nodular lymphocyte-predominant Hodgkins disease represent a monoclonal expansion of B cells. The high load of V(H) gene mutations and signs of intraclonal diversity suggest a relation between L&H cells and germinal-center B cells at the centroblastic stage of differentiation.

Myeloid cell differentiation arrest by miR-125b-1 in myelodysplasic syndrome and acute myeloid leukemia with the t(2;11)(p21;q23) translocation

Most chromosomal translocations in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) involve oncogenes that are either up-regulated or form part of new chimeric genes. The t(2;11)(p21;q23) translocation has been cloned in 19 cases of MDS and AML. In addition to this, we have shown that this translocation is associated with a strong up-regulation of miR-125b (from 6- to 90-fold). In vitro experiments revealed that miR-125b was able to interfere with primary human CD34+ cell differentiation, and also inhibited terminal (monocytic and granulocytic) differentiation in HL60 and NB4 leukemic cell lines. Therefore, miR-125b up-regulation may represent a new mechanism of myeloid cell transformation, and myeloid neoplasms carrying the t(2;11) translocation define a new clinicopathological entity.

Lymphohistiocytic T‐cell lymphoma (anaplastic large cell lymphoma CD30+/Ki‐1 + with a high content of reactive histiocytes)

We describe 13 cases of a peculiar lymphoid tumour containing very large numbers of reactive histiocytes. The tumours occurred in young patients (mean age 14.8 y) who presented with systemic symptoms and superficial lymphadenopathy. Microscopic examination revealed a diffuse effacement of lymph node structure due to the presence of histiocytes intermingled with a variable number of anaplastic large lymphoid cells. The latter, in some cases, were isolated, while in others they were arranged in clusters or were diffusely present in residual sinuses. The large anaplastic cells expressed the activation markers CD30 (Ki‐1), CD25 (interleukin‐2 receptor), CD70 (Ki‐24) and Ki‐27, as well as varying combinations of T‐associated molecules. The histiocytes expressed lysozyme and the CD11b (C3bi‐R), CD11c (p150, 95) CD14, CD68 (KPI) and Ber‐Mac3 antigens. Double staining with the antibody Ki‐67 demonstrated that the proliferating components were the CD30‐positive cells and not the histiocytes. T‐cell receptor beta gene rearrangements were shown in three cases tested. The patients responded well to aggressive chemotherapy and nine are still alive, eight in complete remission. It is suggested that the tumour represents a well‐defined clinico‐pathological entity originating from activated Tlymphocytes.

Molecular Characterization of a New ALK Translocation Involving Moesin (MSN-ALK) in Anaplastic Large Cell Lymphoma

The majority of anaplastic large cell lymphomas (ALCL) are associated with chromosomal abnormalities affecting the anaplastic lymphoma kinase (ALK) gene which result in the expression of hybrid ALK fusion proteins in the tumor cells. In most of these tumors, the hybrid gene comprises the 5′ region of nucleophosmin (NPM) fused in frame to the 3′ portion of ALK, resulting in the expression of the chimeric oncogenic tyrosine kinase NPM-ALK. However, other variant rearrangements have been described in which ALK fuses to a partner other than NPM. Here we have identified the moesin (MSN) gene at Xq11–12 as a new partner of ALK in a case of ALCL which exhibited a distinctive membrane-restricted pattern of ALK labeling. The hybrid MSN-ALK protein had a molecular weight of 125 kd and contained an active tyrosine kinase domain. The unique membrane staining pattern of ALK is presumed to reflect association of moesin with cell membrane proteins. In contrast to other translocations involving the ALK gene, the ALK breakpoint in this case occurred within the exonic sequence coding for the juxtamembrane portion of ALK. Identification of the genomic breakpoint confirmed the in-frame fusion of the whole MSN intron 10 to a 17 bp shorter juxtamembrane exon of ALK. The breakpoint in der(2) chromosome showed a deletion, including 30 bp of ALK and 36 bp of MSN genes. These findings indicate that MSN may act as an alternative fusion partner for activation of ALK in ALCL and provide further evidence that oncogenic activation of ALK may occur at different intracellular locations.

Relapses of childhood anaplastic large-cell lymphoma: Treatment results in a series of 41 children - a report from the French Society of Pediatric Oncology

PURPOSE To study response to chemotherapy and the outcome of children treated for a relapsed anaplastic large-cell lymphoma (ALCL) and to evaluate the role of bone marrow transplantation (BMT) in these patients. PATIENTS AND METHODS Clinical data concerning the 41 relapses that occurred in 119 patients with ALCL enrolled in 3 consecutive studies since 1975 were analysed. First-line treatment consisted of intensive chemotherapy according to the COPAD protocol for the first series of 12 patients treated between 1975 and 1989 and to the SFOP (French Society of Pediatric Oncology) HM protocols for the 30 patients treated between 1989 and 1997. Twenty-eight patients were treated with CV(B)A (CCNU, vinblastine, ara-C with or without bleomycin), and the others with miscellaneous protocols for recurrent disease. Fifteen patients underwent autologous BMT and 1 allogeneic BMT while in CR2. RESULTS Thirty-six of forty-one (88%) patients achieved CR2. With a median follow-up of 5 years, 12 patients died, 9 of their disease and 29 patients are alive in CR2 (20 patients), CR3 (5 patients), CR4 (2 patients), CR5 (1 patient) or CR6 (1 patient). Overall and disease-free survival are respectively 69% (53%-82%) and 44% (29%-61%) at three years. In univariate analysis, patients treated with ABMT while in CR2 did not appear to have a better outcome than the other. Remarkably, a long-lasting remission was obtained in 8 of 13 patients treated with weekly vinblastine for a relapse including 6 relapses occurring after ABMT. CONCLUSIONS Relapsed ALCL are highly chemosensitive but over 40% of the patients experience several relapses. Prolonged conventional chemotherapy based on vinblastine might, in some cases, be as efficient as short intensive treatment with ABMT.

Genomic profiling reveals different genetic aberrations in systemic ALK-positive and ALK-negative anaplastic large cell lymphomas.

Anaplastic large cell lymphoma (ALCL) is a T/null‐cell neoplasm characterized by chromosomal translocations involving the anaplastic lymphoma kinase (ALK) gene (ALK). Tumours with similar morphology and phenotype but negative for ALK have been also recognized. The secondary chromosomal imbalances of these lymphomas are not well known. We have examined 74 ALCL, 43 ALK‐positive and 31 ALK‐negative, cases by comparative genomic hybridization (CGH), and locus‐specific alterations for TP53 and ATM were examined by fluorescence in situ hybridization and real‐time quantitative polymerase chain reaction. Chromosomal imbalances were detected in 25 (58%) ALK‐positive and 20 (65%) ALK‐negative ALCL. ALK‐positive ALCL with NPM‐ALK or other ALK variant translocations showed a similar profile of secondary genetic alterations. Gains of 17p and 17q24‐qter and losses of 4q13‐q21, and 11q14 were associated with ALK‐positive cases (P = 0·05), whereas gains of 1q and 6p21 were more frequent in ALK‐negative tumours (P = 0·03). Gains of chromosome 7 and 6q and 13q losses were seen in both types of tumours. ALCL‐negative tumours had a significantly worse prognosis than ALK‐positive. However no specific chromosomal alterations were associated with survival. In conclusion, ALK‐positive and negative ALCL have different secondary genomic aberrations, suggesting they correspond to different genetic entities.

Genotypic analysis of large cell lymphomas which express the Ki‐1 antigen

The monoclonal antibody Ki‐1 reacts with Reed‐Sternberg cells in Hodgkins disease and with the tumour cells in a minority of large cell non‐Hodgkins lymphomas. This study describes the results of immunophenotypic and DNA analysis in 30 cases of non‐Hodgkins lymphoma, all of which expressed the Ki‐1 antigen. The genotypic analysis has been undertaken using both immunoglobulin and T‐cell receptor gene probes. Sixteen cases were shown by this method to be of monoclonal T‐cell origin, six of B‐cell origin, while in eight cases there was no evidence of either T‐ or B‐cell lineage. This confirms previous immunohistological data indicating that non‐Hodgkins lymphomas which express the Ki‐1 antigen may be of either T‐cell or B‐cell origin.

PCR analysis of immunoglobulin heavy chain (IgH) and TcR-gamma chain gene rearrangements in the diagnosis of lymphoproliferative disorders : results of a study of 525 cases

This report summarizes a cumulative 4-year experience in polymerase chain reaction (PCR) analysis of immunoglobin heavy chain (IgH) and TcR-γ chain gene rearrangements in 525 cases of lymphoproliferative disorders. Because the sensitivity of the PCR methodology was found to be tissue dependent, in the study of the presence of clonal cell population in tissues containing a small number of polyclonal lymphocytes, such as skin and gastrointestinal biopsy specimens, we used the multiple–PCR run approach. In this latter methodology, we repeat the PCR reaction from the same sample at least three times to confirm the reproducibility of the results. In the study of 273 cases of B- or T-cell lymphomas with characteristic immunomorphological and clinical features, a clonal IgH or TcR-γ chain gene rearrangement was detected in approximately 80% of cases. A clonal rearrangement involving both IgH and TcR-γ chain genes was found in 10% of cases of both B-cell and T-cell lymphomas. The study of 167 cases of nonneoplastic lymphoid tissue samples showed the presence of clonally rearranged cell populations for IgH or TcR-γ genes in 3 and 9% of cases, respectively. We also applied PCR for the study of 85 cases of lymphoproliferations with no definite diagnosis (i.e., benign versus malignant) after immunomorphological analysis. In 65 cases (76%), the correlation of immunomorphological features with the presence (48 cases) or the absence (17 cases) of clonal lymphoid cell populations led to a definite diagnosis. In almost all these cases, the final diagnosis was found to be in agreement with the clinical course. In the 20 remaining cases (24%), no definite diagnosis could be made. We also assessed the value of PCR in detecting bcl-2/JH gene rearrangement as an additional clonal marker in the diagnosis of follicular lymphoma. Bcl-2/JH rearrangement and/or IgH gene rearrangement was found in approximately 85% (71/85) of follicular lymphoma cases studied.

Large B‐cell lymphoma rich in T‐cells and simulating Hodgkin's disease

Unusual clinicopathological features drew our attention to nine of 208 cases diagnosed as Hodgkins disease. Lymph node biopsy specimens in these cases were immunostained with monoclonal antibodies against B‐cell, T‐cell and Reed‐Sternberg cell associated antigens and epithelial membrane antigen (EMA). Reed–Sternberg‐like and other atypical large cells were dispersed in a diffuse, small lymphocyte‐rich background, consistent more often with the initial diagnosis of diffuse, lymphocyte predominance Hodgkins disease. The clinical stage in these cases was unusually advanced (stages III and IV). Splenomegaly was a common feature (six of nine cases), the male to female ratio was 7:2 and the median age was 55 years (range 25–77). Response to recognized regimes for Hodgkins disease treatment was poor in most cases, and three patients died early of their disease. Large cells were B‐lymphocytes expressing EMA—an immunophenotype similar to nodular, lymphocyte predominance Hodgkins disease. Reed–Sternberg cell and T‐cell associated antigens were absent on large cells. Mature T‐cells, with nuclear irregularities in some instances, predominated in the background. A more appropriate diagnostic category is, therefore, T‐cell‐rich B‐cell lymphoma. The cases represent a 4–5% erroneous diagnosis of Hodgkins disease and further suggest that there is a need for revision of criteria for the diagnosis of the diffuse, lymphocyte predominance variant.