Lingual Thyroid: 35-Year Experience at a Tertiary Care Referral Center

Barbara G. Carranza Leon, MD; Adina Turcu, MD; Rebecca Bahn, MD; Diana S. Dean, MD

Disclosures

Endocr Pract. 2016;22(3):343-349. 

In This Article

Discussion

Herein, we report the largest published case series of LT to date. The etiology of LT remains unclear, but genetic alterations in Foxe1, TITF-1, and PAX-8 have been proposed to contribute to the abnormal thyroid development.[18,19] The first case of LT was described in 1869 by Hickman,[3] who reported the death by suffocation of a newborn baby with an enormous thyroid mass located at the base of the tongue. In 1972, Baughman and colleagues[20] reported thyroid remnants in 18 cadaver tongues. The subsequent year, Neinas and colleagues[5] reported 15 patients with LT seen at Mayo Clinic Rochester, Minnesota, from 1907 to 1971. We identified 29 patients seen over 35 years at the same institution. The larger number of patients identified in our series is likely due to increased availability of imaging studies, improvement in the integration of our medical records, and an increase in the number of patients seen at our institution.

In concordance with previous reports,[15] we found a female to male ratio of almost 5 to 1. The percentage of patients diagnosed during puberty and adolescence (32%) in our series is lower than what has been previously reported (45.1%).[20] Our cohort had a similar prevalence of hypothyroidism at diagnosis (62%) to that previously reported (33 to 62%).[21] None of our patients were hyperthyroid on presentation; fewer than 10 cases of hyperthyroidism in LT have been reported.[9,22]

With one exception, the LT was the only functional thyroid tissue in our series. Previous reports indicated that 93 to 100% of patients with LT had no orthotopic thyroid tissue.[5] We found cough and hoarseness to be the most common presenting symptoms. Other series have reported symptoms including local discomfort, dyspnea, dysphagia, dysphonia, stridor, fullness of throat, and obstructive sleep apnea occurring at any time from infancy through the sixth decade.

Management of LT in the adult is controversial. Most experts agree that no treatment is required when LT is asymptomatic and the patient is euthyroid.[23] Asymptomatic patients require periodic evaluation, including thyroid function testing. Thyroid hormone supplementation is used in hypothyroid patients but might also be useful in euthyroid patients with local symptoms in an attempt to shrink the lingual mass. Ablative RAI therapy is an alternative approach for patients with obstructive symptoms who are deemed unfit for surgery or who decline surgery. The absorbed iodine reduces the size of the lesion by producing degeneration and fibrosis.

While in severely symptomatic cases surgery is the treatment of choice, it is not devoid of complications. Surgery is indicated in patients who fail or worsen on initial medical therapy or who have significant symptoms. The ectopic tissue may be removed either by an intra-oral or an external approach (trans-hyoid or lateral pharyngotomy). The transoral approach avoids injury to deep neck structures and associated complications (such as injury of the lingual nerve, fistula formation, deep cervical infection, and visible scar) and is feasible when the ectopic thyroid tissue is small. However, this approach allows poor exposure of larger masses and is associated with a higher risk of lingual arterial hemorrhage, which may be difficult to control.[24] The external approach has been used for larger and more posterior masses as it gives good visualization for excision and bleeding can be better controlled. The risk of contamination of the neck tissues with saliva and subsequent fistula formation is higher with an external surgical approach.[23] Irrespective of the surgical technique, the procedure should attempt to remove the entire mass in order to prevent regrowth of residual tissue. New minimally invasive procedures, such as transoral ultrasonic resection, transoral laser microsurgery, and transoral robotic surgery, are being introduced to treat symptomatic patients.[11,12,25,26] Radiofrequency ablation has also been described as a treatment option, as it disrupts cellular integrity, causing coagulative necrosis, scarring, and later, tissue contraction without the production of excess heat.[21,26] Auto-implantation of the ectopic gland has been performed with varying degrees of success.[20]

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