Kikuchi-Fujimoto disease (KFD) is an enigmatic, benign and self-limited syndrome characterized by regional lymphadenopathy with tenderness, predominantly in the cervical region, usually accompanied by mild fever and night sweats.
Source : Orphanet J Rare Dis. 1: 18.
The disease - a.k.a. simply as Kikuchi disease - was first noted in the 1970s in Japan. As mentioned above, it features swollen lymph-nodes in the neck region.
Its cause remains unknown.
It's classified as benign, and usually disappears spontaneously after a few weeks or months. It's a nevertheless a concerning syndrome in that it's often misdiagnosed as more serious disease such as TB or Hodgkin's lymphoma - with patients receiving inappropriate and sometimes damaging treatments
See: Kikuchi-Fujimoto disease: a sheep in wolf's clothing J Otolaryngol Head Neck Surg. 1;41(3):222-6.