Solitary langerhans histiocytosis of the thyroid gland: a case report and literature review.

Langerhans cell histiocytosis (LCH) is a rare disease of antigen presenting cells, with an incidence rate of 4.0-5.4 per 1 million individuals. The most common endocrinological manifestation of classical LCH is associated with the posterior pituitary, presenting as Diabetes Insipidus. However, LCH can affect multiple organs and classification is based on the body system involvement. The disease is confirmed by electron microscopy or immunohistochemical reactivity of histiocytes to CD1a and/or S100. LCH rarely involves the thyroid gland, and management of such disease is controversial. Current literature documents 65 English language reported cases of LCH involving the thyroid gland. We present an unusual case of LCH of the thyroid gland, with variable diagnoses on fine needle aspiration (FNA) cytology, and literature review of all English reported cases.