Lingual thyroid is a rare cause of obstructive sleep apnea (OSA).
A 49-year-old nonobese female was referred to our Sleep Disorders Center for the evaluation of three years of progressive snoring, snort arousals, and apneas that had become non-positional. Seven months prior to evaluation, she noted a sensation of tongue enlargement. She denied dysphagia, stridor, or orthopnea while awake, but she preferred sleeping in a reclining chair to avoid the sensation of her tongue “compressing the back of her throat”. The patient noted progressive daytime somnolence. Her Epworth Sleepiness Scale (ESS) was 15. Her weight remained at 140 pounds (63.5kg, body mass index =23.3). On physical examination, the patient’s voice was slowed, slurred, and without audible stridor. Her tongue base appeared slightly enlarged and a firm, midline mass could be palpated in the posterior tongue base. No thyroid tissue could be palpated in her anterior neck. No other abnormalities were noted. On flexible laryngoscopy, a large, white, vascular mass was noted on the tongue base, nearly obstructing the posterior oropharynx. The scope was passed beyond the mass and the larynx was normal. A thyroid uptake scan demonstrated iodine uptake in the lingual mass, with no evidence of thyroid tissue elsewhere, including in its normal position. There were no symptoms of thyroid hormone excess or deficiency. Based upon these findings, the patient was diagnosed with a lingual thyroid and referred to our institution for further evaluation and treatment recommendations. A magnetic resonance image (MRI) of the head and neck with and without gadolinium demonstrated a 3.5cm x 3.8cm x 4cm mass arising from the tongue base that demonstrated heterogeneous enhancement (Figure 1). No adenopathy or other radiographic abnormalities were noted on the MRI. The patient’s levels of thyroid stimulating hormone (TSH) and free thyroxine were within normal range. Polysomnography demonstrated her to have an apnea-hypopnea index of 79 per hour and, on oximetry, 62 desaturations greater than three percent per hour. Nasal continuous positive airway pressure (CPAP) at 8cm of water pressure relieved obstructive events. The patient was started on nasal CPAP to treat her severe obstructive sleep apnea (OSA). Supplemental thyroxine was prescribed in an attempt to suppress endogenous thyroid stimulating hormone production and thereby shrink the mass. Despite a month of suppressive therapy, the patient noted no change in the size of her tongue and she felt that her sleep and breathing had worsened despite CPAP. The patient was therefore admitted to the hospital for surgical removal of her lingual thyroid. Her procedure included the transoral removal of the 7cm x 5cm x 1.5cm mass and an awake tracheotomy. Pathology demonstrated only benign thyroid parenchyma. Her procedure was uncomplicated, and the tracheostomy was removed prior to discharge home. Eight weeks following the procedure, snoring and apneas had disappeared and her daytime somnolence was gone (ESS=8). An overnight pulse oximetry performed on room air was normal.
Ectopic thyroid tissue, including lingual thyroid, develops because of the incomplete or failure of descent of thyroid tissue during embryogenesis. The tissue can be located at any point along the normal path of descent (thyroglossal duct) from the foramen cecum of the tongue to the isthmus of the thyroid, with the tongue base being the most common location.
Clinicians should evaluate for OSA in patients with upper airway masses and abnormalities in an effort to identify the condition and to assess its response to CPAP.
T.W. Barnes, None.