From suspected lymphoma to self-limiting lymphadenitis: Kikuchi-Fujimoto disease in focus.

Kikuchi-Fujimoto disease (KFD) is a rare, self-limiting form of necrotizing lymphadenitis that primarily affects young adults and often mimics lymphoma or autoimmune lymphadenitis both clinically and histologically. We report the case of a 28-year-old Caucasian woman with a history of Hashimoto's thyroiditis presenting with progressive cervical lymphadenopathy, fever, weight loss, and myalgia. Laboratory findings showed leukopenia, elevated transaminases, and increased LDH. Imaging revealed bilateral lymphadenopathy and mildly enlarged spleen. Histopathological examination of an excised lymph node demonstrated necrotizing lymphadenitis with crescent-shaped histiocytes, plasmacytoid dendritic cells, and karyorrhectic debris. Immunohistochemistry supported the diagnosis and excluded lymphoma, while electron microscopy did not provide evidence of infection. The patient recovered fully without specific treatment. This case highlights the importance of recognizing the characteristic features of KFD to avoid misdiagnosis and overtreatment. Given its potential association with autoimmune disease and recurrence, clinical follow-up is recommended.