Kikuchi-Fujimoto disease (KFD) is a rare, benign condition that often mimics infectious or malignant disorders. We report the case of a 36-year-old woman with atypical lymphadenopathy involving axillary, supraclavicular, and infraclavicular lymph nodes, without cervical involvement. Initial treatment with antibiotics and acetaminophen was ineffective. Laboratory tests excluded infection and other under- lying diseases, while ultrasonography confirmed lymphadenopathy. Excisional biopsy revealed histopathological findings consistent with KFD. Surgical removal of the affected lymph nodes resulted in complete symptom resolution. This case highlights the importance of considering KFD in unexplained lymphadenopathy and the diagnostic value of excisional biopsy.