Hydatid cyst of the thyroid gland in a child.

The hydatid cyst tend to form in the liver or lung but may be found in any organ of the body, including brain, heart, and bones. Thyroid gland involvement is rather rare. Cyst leakage or rupture may even associated with severe allergic reaction to parasite antigens, and may cause anaphylactoid reactions. Herein we reported an additional case of hydatid cyst of the thyroid gland that occurred in a 9-year-old boy who admitted with a painless and cystic thyroid mass. Hemithyroidectomy was performed, and histopathology confirmed the diagnosis of hydatid cyst. Diagnosis of that rare clinical entity is unlikely prior to surgical excision and histopathologic examination. Despite this fact, hydatid disease of the thyroid should be remembered in the differential diagnosis of the cystic thyroid masses, and a high index of suspicion is required.