Langerhans Cell Histiocytosis of Thyroid Gland in a Child: A Case Report and Literature Review.

Introduction Langerhans cell histiocytosis (LCH) is a rare neoplastic disease of dendritic cells with indefinite etiology and pathogenesis.1 The incidence rate of the disease is 4.0–5.4 per 1 million individuals, and the mortality rate is about 3% in adults.2,3 LCH is often encountered in pediatric patients and can be observed as single-organ involvement or multisystemic disease. The disease affects almost every organ in the body, including bone, skin, lung, lymph nodes, hypothalamopituitary axis, liver, spleen, and other sites.2,4 Thyroid involvement in LCH is rare and usually seen in adults.5 When it occurs in children, it is often accompanied by multisystemic involvement.6,7 Because of its rarity, LCH with involvement of the thyroid gland can cause delays in diagnosis and misdiagnosis.