Background: Kikuchi-Fujimoto disease, also called histiocytic necrotizing lymphadenitis, is a rare, self-limited disease of unknown etiology. It is usually characterized by unilateral cervical lymphadenopathy, which can mimic lymph node metastasis. Case presentation: We report a case of follicular thyroid carcinoma concurrent with Kikuchi-Fujimoto disease. A 57-year-old female received sequential neck surgery to complete thyroidectomy for her incidentally diagnosed follicular thyroid carcinoma. Neck ultrasound was conducted to evaluate residual tumor burden before radioiodine therapy. Lymph node metastasis was suspected due to malignant sonographic features with hyperechoic content, the absence of hilum and hypervascularity. Even negative cytology and undetectable thyroglobulin in the lymph node aspirate, this patient received neck lymph node dissection and the histopathological findings were compatible with Kikuchi-Fujimoto disease. Conclusions: Thyroid cancer concurrent with Kikuchi-Fujimoto disease is rare. Nevertheless, it should be taken into consideration in patients of follicular thyroid carcinoma with lymphadenopathy. Lymph node aspirate for cytology and thyroglobulin measurement may provide valuable evidence to exclude a diagnosis of lymph node metastases.