Papillary Carcinoma Thyroglossal Cyst: A Rare Presentation in an 11-Year-Old Girl Child.

Thyroglossal cyst is the most common congenital neck anomaly in children with equal sex incidence, but papillary carcinoma of the thyroglossal cyst in children is rare with only 10 cases reported so far. Even in adults, the incidence of malignancy in the thyroglossal cyst is only 1%. Most cases are diagnosed following surgery on histopathological examination; there is no consensus on the management owing to this rarity and indolent but unpredictable behavior of thyroid cancers. Here, we present one such rare case. Copyright:

INTRODUCTION

Carcinoma in the thyroglossal cyst is rare with an incidence of 1% in adults and 39 years as the mean age of presentation.[1] In children, they are once in lifetime event with only 10 reported cases.[2] Diagnosis is usually incidental on postoperative histopathological examination.[3] Papillary carcinoma is most common followed by squamous cell carcinoma.[3] Treatment is controversial with no established guidelines; Sistrunk procedure is considered adequate if the lesion is confined to thyroglossal cyst whereas total thyroidectomy with or without lymph node dissection followed by radioiodine ablation in other cases.[4]

Here, we present a case of 11-year-old girl with papillary carcinoma in the thyroglossal cyst with normal thyroid and no nodes. The patient underwent Sistrunk procedure and is currently under observation and doing well.

CASE REPORT

An 11-year-old female child presented with a swelling in front of neck of 1 year duration; on examination, a solitary nontender globular swelling measuring 5 cm × 4 cm was noted in the submental triangle in front of hyoid bone with well-defined borders [Figure 1], smooth surface, and nontender, it moved with deglutition and with protrusion of the tongue, thyroid gland was clinically normal, there was no lymphadenopathy, and oral cavity was unremarkable. Provisional diagnosis of the thyroglossal cyst was made. Routine investigations and thyroid function test were within normal limits; ultrasound of the neck showed midline swelling in the infrahyoid region with solid and cystic components with hypoechoic mural nodule and multiple foci of calcifications; thyroid gland was unremarkable. Fine-needle aspiration cytology of the swelling showed features of papillary carcinoma. Contrast-enhanced computed tomography scan revealed a lobulated cystic lesion measuring 55 mm × 44 cm × 35 mm in the anterior neck just below the hyoid bone with solid component showing intense enhancement (170–180 HU) [Figure 1b]. With above findings, the patient was planned for Sistrunk procedure. Intraoperatively, there was swelling measuring 5 cm × 4 cm in the submental triangle with a stalk extending to the body of hyoid bone [Figure 1c], and going through it, there was no infiltration of surrounding structures and no obvious lymphadenopathy. Postoperative course was uneventful, drain was removed on the postoperative day (POD) 2, and the patient was discharged on POD3. Histopathological report showed a 5.5 cm × 4 cm × 5 cm swelling with solid and cystic components with multiple small papillary projections; on gross examination, microscopic picture showed papillary carcinoma-classical type [Figure 2a] with lymph vascular invasion, and two lymph nodes were identified of which one showed papillary carcinomatous deposits [Figure 2b]. After multidisciplinary discussion, the patient was advised total thyroidectomy and bilateral lymph node dissection, but her parents refused surgery; after 2 years of follow-up, the patient is clinically normal and repeat ultrasound of the neck did not show any abnormality in the thyroid or lymphadenopathy.

Figure 1

(a) Clinical picture and (b) computed tomographic scan showing lobulated cystic swelling in the anterior neck, just below hyoid bone with solid component showing intense enhancement (marked with solid arrow), and (c) intraoperative picture showing cyst attached to hyoid bone

Figure 2

(a) Low-power view of thyroglossal cyst with cyst lined by flattened epithelium and papillary projections. (b) Section of the lymph nodes showing metastatic colloid follicles below capsule

DISCUSSION

Thyroglossal duct cyst carcinoma (TGDCa) is a rare condition with an incidence of 1%, with slightly higher female incidence of 1.6:1.[13] The TGDCas are considered to be caused by the mutations in genes, such as the thyroid transcription factors TITF1, TITF2 and PAX8, responsible for the development of the thyroid follicular cells.[15]

Most cases of TGDCa carcinoma are diagnosed during the third and fourth decades of life.[3]

Usually, the diagnosis is only made postoperatively after excision of the cyst.[3] Ultrasonography (USG) is the initial investigation of choice.[25] On USG, a benign TGDCa can be anechoic, homogenously hypoechoic, homogenously hyperechoic (pseudo-solid), or heterogeneous in appearance. If calcification is seen within, malignancy needs to be suspected.[5] The other possibilities to be considered during USG examination are dermoid cyst, epidermoid cyst, and synovial sarcoma.[5]

There are two theories of origin of TGDCa First – the de novo theory, based on the fact that in 62% of cases, ectopic thyroid tissue can be identified histopathologically,[5] and this is supported by the absence of a medullary carcinoma in the thyroglossal cyst. The second theory is metastatic theory which suggests that thyroglossal cyst carcinoma is metastatic from an occult primary thyroid gland.[5] There are differences in the presentation of thyroglossal duct carcinoma compared to thyroid carcinoma such as younger age of presentation, large size, surrounding muscle invasion, involvement of level I, II, and III lymph nodes, and rare involvement of central compartment lymph nodes.[4]

Strict criteria are required to diagnose primary TDC carcinoma, as proposed by Joseph and Komorowski.[4] These are a thyroglossal remnant, ectopic thyroid nests within the cyst wall, and a clinically normal thyroid gland.[4]

Although the Sistrunk technique is the standard surgical procedure for thyroglossal duct cyst removal, there are no standardized criteria for thyroid gland and lymph node surgery once cancer is incidentally found in the thyroglossal duct cyst[2] and also when a diagnosis of malignancy in the thyroglossal duct cyst is obtained preoperatively.[3] In general, management of the patients depends on the spread of tumor.[3] Limited tumors are managed by regular monitoring, while the more aggressive ones are managed by total thyroidectomy and radioiodine ablation.[4]

There are reports of managing incidental TGDCa by Sistrunk operation alone for nonmetastatic disease with thyroxin suppression. Regular follow-up to detect any recurrence in the thyroid gland is essential in cases where the thyroid gland is not resected.[4] Others suggest a radical approach and recommend thyroidectomy with or without radioiodine ablation in all cases.[4] Thyroidectomy is recommended in cases where (a) the thyroid gland is found to be nodular, with a cold nodule in a thyroid iodine uptake scan, (b) enlarged lymph nodes are present, or (c) a history of neck irradiation exists, (d) the presence of other high-risk features such as age more than 45 years and positive margins on histopathology examination.[5]

CONCLUSION

This rare disorder needs a consensus opinion and multidisciplinary team management. Thyroidectomy in thyroglossal duct carcinoma is still a controversial subject. Considering excellent prognosis of thyroid malignancies and need of lifelong thyroid replacement, we recommend a conservative approach in children.

Consent and ethical clearance

Informed consent was obtained from the father of the child for the publication of case report and photographs. Ethical committee review not required, as it is a retrospective case report.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient's father has given consent for images and other clinical information to be reported in the journal. The patient's father understands that the names and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.