Abstract
Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy is a rare disease involving the lymph nodes. Extranodal RDD involving the thyroid is extremely rare. So far, six cases of RDD involving thyroid have been reported in the literature; all have occurred in females with a mean age of 56.3 years. Clinically, radiologically and cytologically, all the cases were initially diagnosed as thyroid malignancies with lymph nodal metastasis. The final diagnosis was made histologically only after total thyroidectomy. We herein, present a seventh case of RDD involving the thyroid in a 15-year-old female, diagnosed first on fine needle aspiration cytology (FNAC). We conclude that FNAC is a useful diagnostic procedure for RDD involving thyroid; it can avoid an unnecessary thyroidectomy.