Thyroid involvement in Rosai-Dorfman disease.

Rosai-Dorfman disease (RDD) with thyroid involvement is extremely rare; we herein present the sixth known case with a review of the previously reported five cases and discuss the clinicopathological characteristics of this entity. RDD with thyroid involvement has occurred only in females with a mean age of 56.3 years, which is significantly different from nodal RDD predominantly seen in young males. Besides this, autoimmune thyroiditis is frequently associated in RDD with thyroid involvement, which raises a suspicion of a common pathogenesis of both entities. RDD with thyroid involvement is commonly misdiagnosed preoperatively as thyroid malignancy with lymph node metastasis, which may lead to overtreatment and postoperative complication. Clinical presentations might be helpful for a preoperative differential diagnosis; while thyroid function, sonography, thyroid isotope scan, and fine needle aspiration have been less useful. All six cases were treated by surgery and complete remission was seen. However, two patients with a preoperative diagnosis of benign disease suffered from hypothyroidism due to total thyroidectomy.