Background: Castleman's disease is a rare disorder of the lymphoid system characterized by noncancerous growths that may develop in lymph node tissues throughout the body.It is most common in the neck, mediastinum, and abdominal lymph nodes.Case Report: Here we describe a 40-year-old woman with asymptomatic cervical Castleman's disease in the left thyroid gland, who was found to have nodular goiter and underwent therapeutic surgery to remove the mass. Conclusion:After the occurrence of this case, our clinician should not only master the diagnosis of common diseases, but also have an understanding of the clinical characteristics of rare diseases.