Advances in the treatment and prognosis of anaplastic lymphoma kinase negative anaplastic large cell lymphoma.

Anaplastic lymphoma kinase negative anaplastic large cell lymphoma (ALK- ALCL) is a definite entity in the WHO 2016 Classification that represents 2-3% of non-Hodgkin lymphoma (NHL) and 12% of T-cell NHL cases. ALK- ALCL lacks ALK protein expression, but expresses CD30 and has morphologic features similar to ALK positive anaplastic large cell lymphoma (ALK+ ALCL). Some studies indicate that ALK- ALCL and ALK+ ALCL possess different molecular and genetic characteristics. Besides, ALK- ALCL is worse than ALK+ ALCL in terms of treatment outcome, prognosis, and long-term survival. This review is aimed at summarizing information about ALK- ALCL, especially with respect to the treatment and prognosis.