We describe a rare case of intramammary and axillary lymphadenopathy caused by Kikuchi-Fujimoto disease (KFD). A 30-year-old woman presented with enlarged axillary lymph nodes and a right breast mass with tenderness. Computed tomography, ultrasonography, F-2-deoxy-fluoro-D-glucose positron emission tomography and fine-needle aspiration cytology were performed, and malignant lymphoma (ML) was suspected. Histological diagnosis of a needle biopsy and surgical specimen showed histiocytic necrotizing lymphadenitis. It is important to differentiate KFD from ML because of differences in treatment choice and clinical outcome.