Unusual endolaryngeal extension of a large thyroglossal duct cyst.

INTRODUCTION Thyroglossal duct cysts account for approximately 70% of congenital neck abnormalities. Hoarseness of voice and the extension of the cyst into the larynx are very uncommon. CLINICAL PICTURE We present a patient with a long history of a large thyroglossal cyst who developed progressive hoarseness of voice. The cyst had protruded into the larynx producing the appearance of a laryngeal neoplasm. Computed tomography (CT) clearly demonstrated the nature of the cyst and its encroachment into the larynx. TREATMENT This was safely excised with a Sistrunk procedure and a temporary tracheostomy to maintain a secure airway, in view of the possibility of postoperative supraglottic oedema. CONCLUSION Endolaryngeal extension of the thyroglossal duct cyst is rare. Evaluation of unusual large midline neck masses should include a CT scan. The intralaryngeal component of the cyst can be easily dissected off from the neighbouring structures during dissection in the Sistrunk procedure. A tracheostomy may be needed.