Langerhans cell histiocytosis of thyroid: Case report with review of literature.

Langerhans cell histiocytosis (LCH) is a rare monoclonal disease of antigen presenting cells. Involvement of thyroid gland by LCH is exceedingly rare. Herein, we present a case of LCH involving the thyroid in a 38-year-old woman. Our patient presented clinically as a case of primary thyroid neoplasm. Presence of elongated, epithelioid neoplastic cells with grooved nuclei along with presence of background eosinophils were seen on fine-needle aspiration cytology (FNAC) and histopathology. Positive staining for CD1a and S100 immunohistochemistry confirmed the diagnosis of LCH. Patient was given combination chemotherapy and has responded well to the same without any complaints for last 6 months. With this report, our goal is to expand awareness of this rare tumor in the thyroid. Consideration at the time of FNAC and its correct diagnosis on subsequent excision is imperative for patient management.