ALK-positive large B-cell lymphoma: a clinicopathological and molecular characteristics analysis of seven cases.

Anaplastic lymphoma kinase-positive large B-cell lymphoma (ALK+ LBCL) is a rare and highly aggressive lymphoma with characteristic ALK rearrangements. Various fusion genes involving ALK have been demonstrated, but the influence of the ALK fusion partners on ALK protein expression and the genetic characteristics of ALK+ LBCL remain relatively unknown. In this study, we conducted an extensive clinicopathological and molecular analysis on seven cases of ALK+ LBCL to explore the correlation between ALK fusion genes and ALK protein expression, thereby enriching the genetic characteristics of this tumour. We integrated the findings from clinical, histopathological/immunophenotypic, and molecular studies, including three samples subjected to next-generation sequencing, and six cases underwent RNA-based ALK fusion gene detection. We identified five distinct types of ALK fusion genes, including CLTC, NPM1, PABPC1, SEC31A, and TFG. Notably, only the NPM1::ALK fusion showed nuclear and cytoplasmic ALK staining, and the remaining four fusion genes resulted in cytoplasmic ALK staining. Our analysis revealed that the CLTC::ALK fusion resulted in a unique cytoplasmic perinuclear Golgi zone focal granular heterogeneous staining pattern of ALK. Additionally, we identified six potentially clinically significant gene mutations, including TET2, CHD2, DTX1, KMT2D, LRP1B, and XPO1. Furthermore, in all cases, the absence of 5-hydroxymethylcytosine (5hmC) was observed. We present seven cases of ALK+ LBCL, discussing the correlation between fusion genes and ALK protein expression, and enhancing our understanding of the genetic attributes of this tumour. This study also shows the loss of 5hmC in nearly all seven ALK+ LBCL cases, independently of TET2 mutations.

Wang X ，Yi H ，Liu Q ，Guo T ，Li A ，Ouyang B ，Li Y ，Zhang Y ，Xu H ，Dong L ，Wang X ，Wang C ... -  《-》

Acquired resistance to crizotinib in novel CDK14-ALK and CLTC-ALK fusions of ALK-positive large B-cell lymphoma identified by next-generation sequencing.

Xia Y ，Zhang L ，He W ，Pan H ，Fang J ，Cui G ... -  《-》

ALK-positive large B-cell lymphoma (ALK + LBCL) with aberrant CD3 expression.

ALK-positive ( +) large B cell lymphoma (ALK + LBCL) is a rare distinct subtype of diffuse large B cell lymphoma presenting with high stage and aggressive behavior. Although B cell markers such as CD20, CD19, and CD22 are generally negative, plasmacytic markers including CD138, CD38, and MUM1 are positive. T cell markers are negative with rare exceptions. We report an unusual case of ALK1 + LBCL in a 58-year-old man with partial expression of CD3 without other T cell antigen expression. The tissue was evaluated with flow cytometry, immunohistochemistry, fluorescent in situ hybridization, and gene rearrangement studies. Gene rearrangement studies for IGH and TCR gamma were performed. Flow cytometry did not demonstrate any abnormal lymphoid populations. Tissue sectioning shows a malignant plasmacytic large cell neoplasm which expresses CD45 but is negative for CD20, CD79a, and PAX5. Plasmacytic markers CD138 and MUM1 are positive with kappa light chain restriction. Strong granular cytoplasmic expression of ALK is present. FISH showing disrupted ALK supports the diagnosis while MYC, BCL6, and BCL2 are intact. Gene rearrangement studies show coexisting IGH and TCR gamma clones; however, the TCR peak was present within a polyclonal background suggesting the disputed cells are likely only a subset of the T cell population. ALK + LBCL can present with an ambiguous immunophenotype, which warrants the use of multiple B cell, T cell, and plasmacytic antibodies. CD3 expression in this entity is rare and of uncertain clinical significance, but warrants further study.

Baker J ，Zadeh SL ，Aguilera NS 《-》

[ALK-positive large B-cell lymphoma with EBV infection or cyclin D1 expression: a clinicopathological analysis of 3 cases].

Wu WN ，Xiang CX ，Ma DS ，Liu GZ ，Liu H ... -  《-》

ALK-positive large B-cell lymphoma: identification of EML4-ALK and a review of the literature focusing on the ALK immunohistochemical staining pattern.

Sakamoto K ，Nakasone H ，Togashi Y ，Sakata S ，Tsuyama N ，Baba S ，Dobashi A ，Asaka R ，Tsai CC ，Chuang SS ，Izutsu K ，Kanda Y ，Takeuchi K ... -  《-》