Natural killer cell neoplasms.

Neoplasms of natural killer (NK) cells are a group of uncommon but highly aggressive malignancies with a strong geographic predilection, and predominantly involving extranodal sites, particularly the nasal/nasopharyngeal region, and sometimes extranasal areas such as the skin and gastrointestinal tract. This group of tumors is characterized: 1) pathologically by an angiocentric and angiodestructive infiltrate of lymphoid cells that can span a...