ALK and mature T-cell and NK-cell non-Hodgkin lymphoma: It comprises a set of disorders that includes peripheral T-cell lymphoma not otherwise specified (PTCL-NOS), angioimmunoblastic T-cell lymphoma (AITL), anaplastic lymphoma kinase (ALK-) positive and ALK-negative forms of anaplastic large cell lymphoma (ALCL), and enteropathy-associated TCL2.