Abstract
Langerhans cell histiocytosis (LCH) is a rare sporadic proliferative disorder of Langerhans cells. LCH rarely involves the thyroid gland. We report herein a case of a disseminated chronic form of LCH with a diagnosis established by histological examination of the thyroid gland. It is about a 37-year-old female who underwent total thyroidectomy for a thyroid nodule of the right lobe. Histological study showed a granulomatous thyroiditis, and the immunohistochemistry study revealed a strong positivity of histiocytes for the CD1 antigen and for the S100 protein. The incidence of LCH involving the thyroid gland, either as an isolated lesion or as a part of multisystemic disease, is extremely rare.