ALK and anaplastic large cell lymphoma: Nodal PTCL is the common subtype of PTCL, including PTCL not otherwise specified (PTCL-NOS, 25%), angioimmunoblastic T-cell lymphoma (AITL, 18%), anaplastic large-cell lymphoma (ALCL), and both ALK positive (6%) and ALK negative (5%) [1, 3].