Myeloid malignancies with translocation t(4;12)(q11-13;p13): molecular landscape, clonal hierarchy and clinical outcomes.

Translocation t(4;12)(q11-13;p13) is a recurrent but very rare chromosomal aberration in acute myeloid leukaemia (AML) resulting in the non-constant expression of a CHIC2/ETV6 fusion transcript. We report clinico-biological features, molecular characteristics and outcomes of 21 cases of t(4;12) including 19 AML and two myelodysplastic syndromes (MDS). Median age at the time of t(4;12) was 78 years (range, 56-88). Multilineage dysplasia was described in 10 of 19 (53%) AML cases and CD7 and/or CD56 expression in 90%. FISH analyses identified ETV6 and CHIC2 region rearrangements in respectively 18 of 18 and 15 of 17 studied cases. The t(4;12) was the sole cytogenetic abnormality in 48% of cases. The most frequent associated mutated genes were ASXL1 (n = 8/16, 50%), IDH1/2 (n = 7/16, 44%), SRSF2 (n = 5/16, 31%) and RUNX1 (n = 4/16, 25%). Interestingly, concurrent FISH and molecular analyses showed that t(4;12) can be, but not always, a founding oncogenic event. Median OS was 7.8 months for the entire cohort. In the 16 of 21 patients (76%) who received antitumoral treatment, overall response and first complete remission rates were 37% and 31%, respectively. Median progression-free survival in responders was 13.7 months. Finally, t(4;12) cases harboured many characteristics of AML with myelodysplasia-related changes (multilineage dysplasia, MDS-related cytogenetic abnormalities, frequent ASXL1 mutations) and a poor prognosis.

Clinical and biological features of B-cell neoplasms with CDK6 translocations: an association with a subgroup of splenic marginal zone lymphomas displaying frequent CD5 expression, prolymphocytic cells, and TP53 abnormalities.

A translocation involving the cyclin-dependent kinase 6 (CDK6) gene [t(CDK6)] is a rare but recurrent abnormality in B-cell neoplasms. To further characterise this aberration, we studied 57 cases; the largest series reported to date. Fluorescence in situ hybridisation analysis confirmed the involvement of CDK6 in all cases, including t(2;7)(p11;q21) immunoglobulin kappa locus (IGK)/CDK6 (n = 51), t(7;14)(q21;q32) CDK6/immunoglobulin heavy locus (IGH) (n = 2) and the previously undescribed t(7;14)(q21;q11) CDK6/T-cell receptor alpha locus (TRA)/T-cell receptor delta locus (TRD) (n = 4). In total, 10 patients were diagnosed with chronic lymphocytic leukaemia, monoclonal B-cell lymphocytosis or small lymphocytic lymphoma, and 47 had small B-cell lymphoma (SmBL) including 36 cases of marginal zone lymphoma (MZL; 34 splenic MZLs, one nodal MZL and one bronchus-associated lymphoid tissue lymphoma). In all, 18 of the 26 cytologically reviewed cases of MZL (69%) had an atypical aspect with prolymphocytic cells. Among the 47 patients with MZL/SmBL, CD5 expression was found in 26 (55%) and the tumour protein p53 (TP53) deletion in 22 (47%). The TP53 gene was mutated in 10/30 (33%); the 7q deletion was detected in only one case, and no Notch receptor 2 (NOTCH2) mutations were found. Immunoglobulin heavy-chain variable-region (IGHV) locus sequencing revealed that none harboured an IGHV1-02*04 gene. Overall survival was 82% at 10 years and not influenced by TP53 aberration. Our present findings suggest that most t(CDK6)+ neoplasms correspond to a particular subgroup of indolent marginal zone B-cell lymphomas with distinctive features.

[Lymphoplasmacytic lymphoma or multiple myeloma: immunoglobulins may lead to misdiagnosis]. / Lymphome lymphoplasmocytaire ou myélome multiple : quand les immunoglobulines induisent en erreur.

We report here a case of lymphoplasmacytic lymphoma with IgA paraproteinemia and a case of concomitant Waldenström macroglobulinemia and monoclonal gammapathy of unknown significance. These rare cases show that the isotype of a monoclonal immunoglobulin does not allow to foresee every time the underlying pathology. Clinical data and medical imaging are essential. From a biological point of view, additional analysis such as immunophenotyping, cytogenetics and molecular biology are required in addition to the cytological features in order to make an accurate differential diagnosis between lymphoid and plasma cell malignancy.

[Chronic lymphocytic leukemia with t(14 ;18) and trisomy 12: a case report]. / Leucémie lymphoïde chronique avec t(14;18) et trisomie 12 : un cas clinique.

Chronic lymphocytic leukemia (CLL) is a B-cell neoplasm defined by the presence of at least 5×109 G/L monoclonal B lymphocytes in the peripheral blood. It is the most common type of leukemia in adult patients from Western countries. CLL is characterized by a gradual accumulation of small, longliving, immunologically dysfunctional, morphologically mature-appearing B-lymphocytes in blood, bone marrow and lymphoid tissues. It has also been reported that CLL cells have a proliferation rate higher than previously recognized, particularly in the lymphoid tissues. The flow cytometry analysis of typical CLL identifies a monotypic B-cell population expressing a low level of surface immunoglobulins, light chain being either kappa or lambda-, CD5+, CD19+, CD23+, CD79b (dim), negative for FMC7 and CD10. Clinical presentation, course and outcome are highly variable. Interphase fluorescent in situ hybridization (I-FISH) identifies chromosomal abnormalities in about 80% of cases, most commonly involving 13q14 (55%), 11q22-23 (18%), or 17p13 deletions (7%) and trisomy 12 (16%). Therefore, five prognostic categories have been defined with a statistical model, showing the shortest median survival and treatment-free intervals in patients harboring 17p and 11q deletions, followed by trisomy 12 and a normal karyotype, whereas 13q deletion as the sole abnormality is associated with the best prognosis. We report here a rare case of CLL in a 54 year-old-man.