T- and NK-cell lymphoma update

The 2008 WHO classification of mature T- and NK-cell neoplasms recognizes 18 distinct clinico-pathological entities and a number of subgroups or provisional disease categories. The most important changes compared to the 2001 edition include recognition of chronic lymphoproliferative disorders of NK cells and EBV-positive T-cell lymphoproliferative disorder of childhood entities; redefinition of subcutaneous panniculitis-like T-cell lymphoma (TCL) as a neoplasm of T cells expressing α/β T-cell receptor and recognition of primary cutaneous γ/δ TCL, and separation of anaplastic large cell lymphoma into ALK positive and negative subtypes. With the help of molecular tools, investigators have unveiled some of the molecular events in T-cell lymphomagenesis. These include delineation of similarities between physiological T-cell subsets and some TCL and a number of gene specific genetic alterations. Although the findings have a long way to go before a clinical translation can be achieved, they raise a number of new potential diagnostic and treatment targets.