Thyroid gland involvement as the unique presentation of Langerhans cell histiocytosis is a rare phenomenon that can result in misdiagnosis. We report a case of Langerhans cell histiocytosis (LCH) presenting as a thyroid mass. It is a 52-year-old woman who presented an enlarged, diffusely firm, nontender, nonmobile, and not particularly nodular thyroid gland with mild compressive symptoms. Ultrasound and fine-needle aspiration showed a unique right node with benign signs. Patient was referred to our Ambulatory Surgery Department, where a hemithyroidectomy was performed. Histologic evaluation of the right thyroid gland revealed an involvement by LCH, confirmed by immunohistochemical analysis showing Langerhans cells that were positive for CD1a. LCH was a completely incidental occult finding apparent only after surgical resection and examination of the gland. Patient was evaluated, and no evidence of systemic affectation was found. LCH can rarely involve the thyroid gland in adults. Few cases have been reported in the literature. Most patients had evidence of LCH involving other anatomic sites.