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KAREN H.CALHOUNMDRONALD B.KUPPERSMITHMD
Carcinoma arising in a TGDR is rare. It is usually diagnosed after the excision of a presumed benign thyroglossal duct cyst. A 1994 review reported 155 cases in the world literature.1 Of these, approximately 80% were papillary or a follicular variant of papillary thyroid cancer. The same review quoted from the Dutch registry a TGDCa incidence of 0.48% (2/413). Unfortunately, since the literature consists of multiple case reports, long-term follow-up on a large series of patients is lacking. Well-differentiated carcinomas of the thyroid gland require long-term follow-up for the survival and disease-free interval data to be valuable. The extrapolation of data from well-differentiated thyroid cancers to TGDCa may not be valid.
The prevalence of TGDCa in the Mayo Clinic series was 0.7% (12/741).2 Of these 12 patients, 9 had a thyroidectomy during their treatment. Three of these had thyroidal foci of cancer. One of these had a 1.5-cm focus of papillary cancer in the thyroid and lymph node involvement. The other 2 patients had thyroid lesions smaller than 3 mm. An Italian study3 revealed associated foci of cancer in 40% of cases with only 1 tumor larger than 1 cm. Both of these studies recommended a Sistrunk procedure with a total thyroidectomy.
David Myssiorek, MD
Microscopic foci of thyroid cancer can be found in 2% to 5% of the population without known thyroid disease. Furthermore, encapsulated papillary lesions of the thyroid that are smaller than 1.5 cm can be effectively managed by a partial thyroidectomy alone. If one would not remove a thyroid lobe for documented thyroid cancer, why would one remove an entire thyroid gland for TGDCa?
The standard of care for thyroglossal duct cyst diagnosis is not FNA. Given the young age of many of the patients with these cysts and the low incidence of malignancy associated with them, routine FNA is not practical or cost-effective.
Thyroglossal duct carcinoma does not commonly metastasize, nor does it frequently result in death.4 Multicentric foci of papillary cancer within the thyroid is a known entity, but given the low rate of recurrence in patients who undergo partial thyroidectomy, it is probably of limited significance. The possibility of recurrent nerve damage, superior laryngeal nerve damage, and/or hypocalcemia following a total thyroidectomy probably would not justify this procedure as an adjunct to a Sistrunk procedure. Performing a subtotal thyroidectomy to avoid these complications defeats the rationale for performing a thyroidectomy—ease of surveillance.
Regardless of these research data, in most clinical studies, patients who underwent only a Sistrunk procedure did not have recurrence. In the Mayo Clinic series,2 although total thyroidectomy was advised as an adjunct procedure, there were no recurrences in the patients who did not have a thyroidectomy. Cure rates have been quoted at around 95%.5 The ultimate answer to the question will depend on long-term follow-up reports on patients treated by the Sistrunk procedure alone.
There are times when adding a total thyroidectomy to a Sistrunk procedure is warranted. Patients with a palpable mass in the thyroid gland, earlier exposure to radiation, lymph node metastases, and/or extracapsular spread of the TGDCa should be considered for total thyroidectomy. Although extremely rare, children with TGDCa have been described.6 Given the long life expectancy of a child and the need for continued surveillance, a total thyroidectomy in this situation seems prudent.
Myssiorek D. Total Thyroidectomy Is Overly Aggressive Treatment for Papillary Carcinoma in a Thyroglossal Duct Cyst. Arch Otolaryngol Head Neck Surg. 2002;128(4):464. doi:10.1001/archotol.128.4.464
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