Intrathyroid cysts of thyroglossal duct origin.

Thyroglossal duct cysts develop from a persistent portion of the thyroglossal tract and have been described as occurring anywhere from the base of the tongue to the manubrium. We present two patients who presented with a cystic thyroid nodule due to an intrathyroid thyroglossal duct cyst. A fine-needle aspiration biopsy was performed, which revealed benign squamous cells. Upon exploration, the first patient was found to have a 2-cm cyst within the thyroid isthmus, and in the second patient, a 1-cm cyst was found in the right thyroid lobe. Pathologic analysis revealed the cyst to be lined by a squamous epithelium consistent with a thyroglossal duct cyst. The lesions were completely surrounded by normal thyroid tissue. There was no evidence of a remnant of the thyroglossal duct extending from the thyroid in the region of the cyst. Both patients were treated by thyroid lobectomy and isthmusectomy and have remained without evidence of recurrence. Intrathyroid thyroglossal duct cysts should be included in the differential of patients with cystic thyroid lesions. Fine-needle aspiration revealing benign squamous cells is usually diagnostic and may detect an occult carcinoma arising within the cyst. Surgical resection is curative and should include a Sistrunk procedure if a thyroglossal duct tract is present.