Peripheral T-cell Lymphoma-Not-Otherwise Specified (PTCL-NOS), is a subtype of Peripheral T-cell lymphoma. Peripheral T-cell lymphoma (PTCL) is defined as a diverse group of aggressive lymphomas that develop from mature-stage white blood cells called T-cells and natural killer cells (see figure for an overview of PTCL subtypes). PTCL is a type of non-Hodgkin’s lymphoma (NHL). NHL affects two particular types of white blood cells: B-cells and T-cells. PTCL specifically affects T-cells, and results when T-cells develop and grow abnormally. PTCL-NOS, the most common subtype of PTCL, is aggressive and predominantly nodal...