JAK/STAT3 Signaling Activation Related to Distinct Clinicopathologic Features in Systemic ALK - Anaplastic Large Cell Lymphomas : New Insights into Their Heterogeneity.

Systemic anaplastic lymphoma kinase (ALK)-negative anaplastic large cell lymphoma (ALCL) is a group of heterogenous CD30 + T-cell non-Hodgkin lymphomas. Previous studies have highlighted the importance of JAK/STAT3 signaling activation in the molecular pathogenesis of ALK - ALCLs. In the present study, we aimed to establish a potential relationship between JAK/STAT3 signaling activation and clinicopathologic features in ALK - ALCLs, and further recognize the heterogenous nature of these neoplasms. Immunohistochemistry staining of the phosphorylated-STAT3 (p-STAT3) and dual-specificity protein phosphatase 22 ( DUSP22 ) gene rearrangement analysis were performed. Forty-five cases of ALK - ALCL were divided into 3 groups, including 9 DUSP22 -rearranged ALCLs, 21 p-STAT3 + double-negative (DN) ALCLs (both ALK and DUSP22 rearrangement negative), and 15 p-STAT3 - DN-ALCLs. Morphologically, p-STAT3 + DN-ALCLs exhibited sheet-like neoplastic cells and sometimes showed large pleomorphic cells scattered in a lymphocyte-rich background more frequently than those in other ALK - ALCLs subtypes. Phenotypically, the p-STAT3 + DN-ALCLs frequently expressed cytotoxic molecules, epithelial membrane antigen, and programmed death-ligand 1, whereas CD3 and CD5 expression was not observed. Clinically, patients with p-STAT3 + DN-ALCLs had a better prognosis than those with p-STAT3 - DN-ALCLs. These observations suggest that p-STAT3 + DN-ALCLs represent a distinct subtype of ALK - ALCLs. Identifying ALK - ALCL subtypes by using p-STAT3 staining and DUSP22 rearrangement is a promising approach that may contribute to risk stratification and better treatment decisions in the future clinical practice.