Kikuchi-Fujimoto Disease Coexistent with Papillary Thyroid Carcinoma in a Single Lymph Node

Cervical lymphadenopathy can be developed from various causes such as viral infection, bacterial infection, Kikuchi-Fujimoto disease, tuberculosis, malignancy, and reactive changes. In patients who have malignancy, metastatic lymphadenopathy is possible but it is rare that other concomitant diseases are in the same lymph node. We experienced a case of coexistence of Kikuchi necrotizing lymphadenitis and papillary thyroid carcinoma in a single cervical lymph node. A 38-year-old man who was previously diagnosed with papillary thyroid cancer with cervical lymph nodes metastasis presented with cervical lymphadenopathy. The lymph node biopsy showed tuberculous lymphadenitis. After finishing anti-tuberculosis medication, recurrent lymphadenopathy had developed and a surgical biopsy was performed. At that time, the diagnosis was Kikuchi necrotizing lymphadenitis combined with metastatic papillary carcinoma in a single lymph node.