Thyroid involvement in Langerhans cell histiocytosis: a report of two cases and review of the literature.

Langerhans cell histiocytosis (LCH) is a disorder with unclear etiology and pathogenesis characterized by abnormal clonal proliferation and accumulation of antigen presenting Langerhans' cells at various tissues and organs. Almost all organs or systems may be involved, and the prognosis depends on the involved sites and the presence of organ dysfunction. Thyroid tissue is a rarely affected site in children, and without histopathological evaluation it may be difficult to distinguish from other thyroid disorders because of the similar physical examination, laboratory and imaging findings. Here we report on two patients with histopathologically proven thyroid involvement of LCH. Additionally, the differential diagnosis of diffusely enlarged or multinodular thyroid glands in children is discussed, and a review of the literature of thyroid involvement in LCH is given. In the differential diagnosis of enlarged thyroid glands, especially in the presence of other endocrinological manifestations, LCH must be taken into consideration.