Extranodal peripheral T-cell and NK-cell neoplasms
Jaffe, E.S.; Krenacs, L.; Kumar, S.; Kingma, D.W.; Raffeld, M.
American Journal of Clinical Pathology 111(1 Suppl 1): S46-S55
1999
ISSN/ISBN: 0002-9173 PMID: 9894469 Document Number: 502028
Mature or peripheral T-cell lymphomas are uncommon, accounting for only 10% to 15% of all non-Hodgkin lymphomas, and their classification has been controversial. In contrast to B-cell lymphomas, cytologic features have not been useful in defining disease entities, and cytologic grade has not been useful in predicting the clinical course. Similarly, many entities of T-cell or NK-cell derivation do not have a specific immunophenotype. Clinical features are of major importance, sometimes more important than the precise cell of origin, in defining T-cell and NK-cell neoplasms. Most extranodal T-cell/NK-cell lymphomas have a cytotoxic phenotype. The expression of cytotoxic molecules may predispose to apoptosis by tumor cells and normal bystander cells. Three major categories of extranodal T/NK cell tumors are nasal, intestinal, and subcutaneous panniculitis-like. Hepatosplenic gammadelta T-cell lymphoma is a more systemic disease derived from functionally immature cytotoxic cells. Many extranodal T-cell and NK-cell neoplasms are associated with Epstein-Barr virus (EBV); the association seems site dependent and shows some geographic variation. Tumors resembling any of the 3 prototypes may occur in a variety of extranodal sites. Extranodal T/NK cell lymphomas occur with increased frequency in the setting of immune suppression, especially after organ transplantation.