Intrathyroid thyroglossal duct cyst simulating a thyroid nodule.

A case of intrathyroid thyroglossal duct cyst is reported. A 50-year-old woman presented with a right lateral neck mass that was clinically indistinguishable from a thyroid nodule. Ultrasound-guided fine-needle aspiration biopsy (US-FNAB) revealed normal-looking squamous cells. Right thyroid lobectomy was performed and microscopic examination revealed a cyst lined by squamous epithelium that was consistent with a thyroglossal duct cyst. The lesion was completely surrounded by normal thyroid tissue. Our experience suggests that intrathyroid thyroglossal duct cyst should be remembered in the differential diagnosis of a thyroid nodule. Detection of benign squamous cells by US-FNAB may be useful for ruling out the possibility of a cystic thyroid tumor.