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 (NK cells) (see figure for an overview of PTCL subtypes). PTCL is a type of non-Hodgkin's lymphoma (NHL).[2] PTCL specifically affects T-cells rather than B-cells, and results when T-cells develop and grow abnormally.
PTCL-NOS, the most common subtype of PTCL, is aggressive and predominantly nodal. There are two morphologic variants: the T-zone lymphoma variant and the lymphoepithelioid cell variant.[4][5]
T-zone lymphoma is so named for its involvement in a specific area of the lymph node that consists of a dense accumulation of T-cells.[6]
Lympho-epithelioid lymphoma, also called Lennert's lymphoma, is rare and generally affects older individuals.[7]
^Rodriguez, J.; Gutierrez, A.; Martinez-Delgado, B.; Perez-Manga, G. (2009). "Current and future aggressive peripheral T-cell lymphoma treatment paradigms, biological features and therapeutic molecular targets". Crit Rev Oncol Hematol. 71 (3): 181–198. doi:10.1016/j.critrevonc.2008.10.011. PMID19056295.
^Swerdlow SH, WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 2008