Review ArticleThe Pathology of NK-Cell Lymphomas and LeukemiasNava, Victor E MD, PhD; Jaffe, Elaine S MDAuthor Information From the Hematopathology Section, Laboratory of Pathology, National Cancer Institute, Bethesda, Maryland. The current address of Dr. Nava is Department of Pathology, Georgetown University Hospital, 3900 Reservoir Rd. NW, Washington, DC 20007. Reprints: Elaine S. Jaffe, MD, 10 Center Dr., MSC 1500, Bldg. 10, Rm. 2N-202, Bethesda, MD 20892 (e-mail: email@example.com). Advances in Anatomic Pathology: January 2005 - Volume 12 - Issue 1 - p 27-34 doi: 10.1097/01.pap.0000151318.34752.80 Buy Metrics Abstract Natural killer (NK) cell lymphomas and leukemias are a rare but clinically important group of neoplasms. Most of these tumors are aggressive, with a high rate of mortality. They include extranodal NK/T-cell lymphomas of nasal type and aggressive NK-cell leukemias. Both are Epstein-Barr virus (EBV) associated and show similar epidemiologic features. A closely related entity seen mainly in children is hydroa vacciniforme-like lymphoma, which also is EBV positive. EBV influences the pathophysiology of these tumors, through the induction of cytokines and chemokines. The differential diagnosis of NK-cell malignancies includes fulminant EBV-associated T-cell lymphoproliferative disorder, a condition referred to in the past as fatal infectious mononucleosis. Benign proliferations of NK cells can be seen in association with viral infection. The disease formerly referred to as blastic NK-cell lymphoma is now considered to be a malignancy derived from a dendritic cell precursor. © 2005 Lippincott Williams & Wilkins, Inc.