An Exploration into the Origins and Pathogenesis of Anaplastic Large Cell Lymphoma, Anaplastic Lymphoma Kinase (ALK)-positive

T cell Non-Hodgkin lymphoma is a heterogeneous disease ranging from malignancies arising from thymic T cells halted in development, through to mature, circulating peripheral T cells. The latter cases are diagnostically problematic with many entering the category of peripheral T cell lymphoma, not otherwise specified (PTCL, NOS). Anaplastic Large Cell Lymphoma is one of the exceptions to this whereby aberrant expression of Anaplastic Lymphoma Kinase and distinctive presence of cell surface CD30 places this entity in its own class. Besides expression of a well-studied oncogenic translocation, ALCL, ALK+ may also have a unique pathogenesis with a thymic origin like T lymphoblastic lymphoma but a peripheral presentation akin to PTCL. This review discusses evidence towards the potential origin of ALCL, ALK+ and mechanisms that may give rise to its unique phenotype.