A rare cause of goiter: Langerhans cell histiocytosis of the thyroid. 
Goiter is a very common clinical problem; however, Langerhans cell histiocytosis (LCH) with thyroid involvement that presents as a goiter is very rare.  In this article, we report one case of thyroid LCH.  An 18-year-old male patient presented with goiter, polyuria, polydipsia, and lymphadenectasis of the neck, and LCH was confirmed by a lymph node biopsy and pathological investigation.  Without a thyroidectomy, the goiter shrank after nine cycles of chemotherapy.  In addition, we summarize the reported thyroid LCH cases in the literature from the last 10 years.  LCH usually involves other organs, such as the lungs, bones, skin, pituitary gland, and lymph nodes.  Thyroid LCH is more common in adults than in children, and it may coexist with a thyroid carcinoma.  Without any unique thyroid manifestations, either clinically or by imaging, it is difficult to distinguish thyroid LCH from other thyroid diseases.  Pathology is the gold standard for the diagnosis of LCH.  A fine needle aspiration biopsy (FNAB) may help to diagnosis LCH, although sometimes it leads to misdiagnosis.  Chemotherapy is recommended for multi-system LCH.  Younger patients with widespread disease or who are non-responsive to chemotherapy have poor outcomes.