A 29-year-old Japanese man developed fever, nausea, vomiting, diarrhoea, right lower quadrant abdominal pain and rebound tenderness. With the clinical suspicion of appendicitis, an abdominal CT scan was performed, which revealed mesenteric lymphadenitis. The patient was hospitalised and treated with antibiotics, but was ultimately found to have Kikuchi-Fujimoto disease (KFD). This diagnosis was facilitated by the use of positron emission tomography scan that identified an accessible inguinal lymph node for biopsy and histopathological evaluation. Invasive abdominal surgery was thereby averted and the patient made a complete recovery on subsequent follow-up. Review of the published literature reveals that pseudoappendicitis due to KFD is a rare occurrence that has generally required abdominal surgery to establish the diagnosis, thus supporting the potential value of the approach taken here.