Langerhans cell histiocytosis with thyroid involvement in a 3 year-old child - a case report.

Langerhans cell histiocytosis (LCH), a monoclonal disease of histiocytes, may involve several organ systems but rarely primarily involves the thyroid gland. This report presents an extremely rare case of LCH of the thyroid in a 3-year-old boy who presented with a neck mass for several weeks. LCH of the thyroid should be considered in the differential diagnosis of a child with a thyroid mass. Pulmonary examination should be done in these patients.