ALK and mature T-cell and NK-cell non-Hodgkin lymphoma: The nodal lymphoma group, as classified by the World Health Organization, contains four subtypes: peripheral T-cell lymphoma (PTCL) not otherwise specified (PTCL-NOS), angioimmunoblastic T-cell lymphoma (AITL) and anaplastic large-cell lymphoma (ALCL), either ALK-positive or ALK-negative [2].