|Year : 2017 | Volume
| Issue : 2 | Page : 82-85
Thyroglossal cyst malignancy: Two case reports with review of literature
Lab Operation, SRL Limited, Shimla, Himachal Pradesh, India
|Date of Web Publication||22-Jan-2018|
SRL Limited, Shimla, Himachal Pradesh
Source of Support: None, Conflict of Interest: None
Thyroglossal cyst is formed from the remnant of thyroglossal tract around 8th–10th weeks of gestation. Thyroglossal cyst is the most common congenital mass found in neck midline. Development of carcinoma in thyroglossal cyst is rare, with an incidence of 0.7%–1.0%. Nearly 90% of the malignancies developing in thyroglossal cyst are thyrogenic in origin arising from the ectopic thyroid tissue. Squamous cell carcinoma accounts for <1% of all thyroglossal cyst malignancies. Thyroglossal cyst carcinomas of thyrogenic origin are managed with Sistrunk procedure along with thyroidectomy. Thyroidectomy is recommended because thyroid carcinomas, especially papillary carcinomas, are multifocal and multicentric. Thyroidectomy is not required in thyroglossal cyst carcinomas of nonthyroid origin. We report two cases of thyroglossal cyst with incidental finding of papillary carcinoma of thyroid origin due to their rarity with a review of literature.
Keywords: Papillary carcinoma, thyroglossal cyst, thyroglossal cyst carcinoma, thyroglossal tract
|How to cite this article:|
Puri S. Thyroglossal cyst malignancy: Two case reports with review of literature. J Head Neck Physicians Surg 2017;5:82-5
|How to cite this URL:|
Puri S. Thyroglossal cyst malignancy: Two case reports with review of literature. J Head Neck Physicians Surg [serial online] 2017 [cited 2019 Sep 15];5:82-5. Available from: http://www.jhnps.org/text.asp?2017/5/2/82/223763
| Introduction|| |
Thyroglossal tract is formed during early gestation when thyroid gland descends from the foramen cecum to its location below the thyroid cartilage. The tract involutes at 8th–10th weeks of gestation. Failure of thyroglossal tract to involute leads to the formation of thyroglossal remnant which may be a cyst, tract or duct, fistula, or an ectopic thyroid with cyst or duct. A thyroglossal duct cyst (TDC) is the most common congenital mass in midline neck and the most common anomaly in the development of the thyroid gland. Neoplasm in thyroglossal duct remnant was first described by Brentano and Uchermann in 1915. The median age at presentation is 40 years. Definitive surgical management requires excision of the cyst and the path's tracts and branches. The strong association between the tract and the hyoid bone requires the simultaneous removal of the central portion of the hyoid bone to ensure the complete removal of the tract (Sistrunk procedure). Recurrence is unlikely, except in cases with skin involvement or intraoperative cyst rupture. Thyroidectomy is done in tumors of thyrogenic origin.
| Case Reports|| |
A 24-year-old male presented to ENT outpatient department (OPD) with complaint of midline submandibular swelling progressively increasing in size for the last 2 years. The swelling was painless and not associated with difficulty in breathing or swallowing. An ultrasonography (USG) of neck was performed. USG showed a well-defined cystic lesion with a few septations and small hyperechoic area in anterior neck with an impression of thyroglossal cyst or lymphangioma–submandibular region [Figure 1]a. The swelling was excised and sent for histopathological examination (HPE). Grossly, a single gray-brown soft tissue was received measuring 4.5 cm × 3.0 cm × 2.0 cm [Figure 1]b. Cut surface was cystic with septae filled with thin brown fluid [Figure 1]c. Microscopic examination showed multiloculated cystic neoplasm with thin cuboidal to pseudostratified lining at most places, foci of papillary proliferation with hyalinized cores, and microcalcification. The nuclei had optically clear appearance and focal grooves. Cyst wall comprised of fibroconnective tissue [Figure 1]d. A diagnosis of papillary thyroid carcinoma with possibility of carcinoma arising in thyroglossal cyst was favored over metastatic papillary thyroid carcinoma. A repeat USG neck was done to assess the thyroid lobes. The thyroid lobes were normal in size and shape and the patient was euthyroid. The patient refused for thyroidectomy and is kept on regular follow-up with nuclear medicine OPD.
|Figure 1: (a) Ultrasonography showing a well-defined cystic lesion with a few septations and small hyperechoic area in the anterior neck. (b) Gross features showing a single gray-brown soft tissue. (c) Cut surface is cystic with septae filled with brown fluid. (d) Histopathological examination showing cyst wall lined by papillary proliferation, nuclei having optically clear appearance and focal grooves|
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A 56-year-old male presented to ENT OPD with complaint of midline swelling of neck for the last 4 years. There was no difficulty in breathing, swallowing, or change in voice. On examination, there was 3 cm × 3 cm firm, nontender, midline swelling at the level of hyoid bone which moved with protrusion of tongue. On USG, an anechoic cystic lesion measuring 2.7 cm × 2.3 cm × 2.0 cm within the strap muscle cranial to thyroid gland with fine internal echoes and amorphous eccentric calcified specs was identified. Thyroid function tests (TFTs) were within the normal range. A fine-needle aspiration (FNA) was performed from the midline swelling. Aspiration smears showed colloid and benign follicular cells with possibility of thyroglossal cyst. Sistrunk procedure was performed and the excised cyst was submitted for HPE. Grossly, the cyst was gray-brown, measured 3.0 cm × 3.0 cm × 2.5 cm and was filled with brown mucoid material. Microscopic examination showed a fibrous cyst wall with thyroid tissue and cholesterol clefts. The lining was thrown into papillae with psammoma body formation. The lining cells showed optical clearing, grooving, and intranuclear cytoplasmic inclusions [Figure 2]a and [Figure 2]b. This focus measured <1 cm. A HPE diagnosis of thyroglossal cyst with findings suspicious of papillary microcarcinoma was reported. The histopathological findings were confirmed with immunohistochemistry which showed immunopositivity for CK19 [Figure 2]c and immunonegativity for anti-p63 [Figure 2]d and CD56. A repeat USG was done which showed normal-sized thyroid lobes. Since papillary carcinoma is known to be multifocal and multicentric, there was a risk of thyroid cancer, so total thyroidectomy was performed and the specimen was submitted for HPE. HPE of thyroid lobes showed benign thyroid parenchyma with macro- and micro-follicles lined by attenuated-to-hyperplastic follicular epithelium.
|Figure 2: (a) Histopathological examination showing fibrous cyst wall lined by papillae with psammoma bodies. (b) The lining cells showed optical clearing, grooving, and intranuclear inclusions. (c) Immunohistochemistry showing immunopositivity for CK19 and (d) immunonegativity for anti-p63|
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| Discussion|| |
Thyroglossal duct is an embryonic structure which traces the path of descent of thyroid gland. The duct is obliterated at the 8th–10th weeks of gestation. Thyroglossal duct fails to involute in 7% of cases. TDC is the most common congenital mass found in the neck midline; however, 10% of them can be found in the lateral neck. TDC is found in the thyrohyoid (60%), suprahyoid (2%), suprasternal (13%), and intralingual (25%) regions.
Malignant transformation in TDC is uncommon, incidence varies from 0.7% to 1.0%. Primary carcinoma of the thyroglossal duct is defined by criteria suggested by Widström et al.: histological identification of TDC by the presence of epithelial lining in duct with normal thyroid follicles within the wall of cyst, normal thyroid tissue adjacent to the tumor, and HPE of the thyroid gland showing no sign of primary carcinoma.
Two theories are described to explain the thyrogenic origin of TDC carcinomas. First is the de novo theory based on the fact that in 62% of cases, ectopic thyroid tissue can be identified histopathologically. This is supported by the absence of medullary carcinoma in TDC which arises from parafollicular cells.
The second is the metastatic theory which suggests that the TDC carcinoma is metastatic from an occult thyroid gland malignancy.
Mobini et al. concede that squamous cell carcinoma (SCC) is probably the only true carcinoma of thyroglossal duct, since other malignancies develop in ectopic thyroid tissue. Nearly 90% of TDC carcinomas originate from ectopic thyroid tissue. The most common tumor arising from ectopic thyroid tissue is papillary carcinoma (75%–80%), but other thyroid tumors such as follicular, Hürthle cell, and mixed papillary–follicular carcinomas have been reported. Thus, SCC of thyroglossal duct is very rare and has a poor prognosis with a mortality of 30%–40%. The incidence of thyroid carcinoma along with TDC carcinoma is <1%; however, the frequency of thyroid carcinoma along with TDC is increasing, thus making thyroid gland evaluation an important component of TDC workup. Thus, preoperative evaluation should include detailed head and neck examination, TFTs, radiological examination, and FNA of TDC and thyroid if any nodule or swelling is apparent.
A Sistrunk procedure with clear surgical margins and adjunct treatment with radioactive iodine is the standard regimen for TDC papillary carcinoma. It involves resection of the cyst, the body of the hyoid bone, and a cone of the base of the tongue muscle up to the foramen cecum. Sistrunk procedure may be combined with total thyroidectomy. Multicentricity and multifocality are common in papillary thyroglossal carcinomas, as a second malignant lesion is present in 10% of cases with thyroid cancer, thus supporting thyroidectomy in these cases. No additional treatment to Sistrunk procedure for pure TDC of squamous cell origin is recommended. In contrast, for de-differentiated thyroid malignancy in a TDC, total thyroidectomy is indicated whether thyroid is involved clinically or radiologically or not. In case of large tumors >1 cm, invasion through the duct cyst wall, or suspected foci in the thyroid gland, a total thyroidectomy followed by I 131 ablation and thyroid-stimulating hormone suppression is the frequently proposed treatment. Recurrence is unlikely, except in cases with skin involvement or intraoperative cyst rupture.
| Conclusion|| |
Development of malignancy in TDC is rare. A high index of suspicion, imaging, and FNA of midline neck swelling should be performed. All midline neck lesions should be examined histopathologically to know the origin and nature of lesion. Surgeons should be aware of TDC in surgical planning, postoperative treatment, and should include it in the differential diagnosis of anterior midline neck mass. Regular follow-up to detect any recurrence in the thyroid gland is essential, particularly in cases where the thyroid gland is not resected.
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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
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[Figure 1], [Figure 2]