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| CASE REPORT |
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| Year : 2020 | Volume
: 4
| Issue : 2 | Page : 57-60 |
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Imaging in malignant thyroglossal duct cyst
Ashitha Shankaralingappa1, Aruna Raman Patil1, Shrivalli Nandikoor1, Satish Nair2, Harini Raju3
1 Department of Radiology, Apollo Hospitals, Bengaluru, Karnataka, India
2 Department of ENT-HNS, Apollo Hospitals, Bengaluru, Karnataka, India
3 Department of Pathology, Apollo Hospitals, Bengaluru, Karnataka, India
| Date of Submission | 26-Sep-2019 |
| Date of Acceptance | 07-Jan-2021 |
| Date of Web Publication | 19-Feb-2021 |
Correspondence Address:
Dr. Ashitha Shankaralingappa
Department of Radiology, Apollo Hospital, 154/11, Opp. IIM, Bannerghatta Road, Bengaluru - 560 076, Karnataka
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/aiao.aiao_22_19
Thyroglossal duct cyst (TGDC) is the most common congenital neck mass, located in the midline of the neck. Majority are benign. Malignant TGDC is an extremely rare condition and is detected incidentally. We report here a case of papillary carcinoma within thyroglossal duct cyst. Keywords: Papillary carcinoma, thyroglossal duct cyst, thyroid
How to cite this article:
Shankaralingappa A, Patil AR, Nandikoor S, Nair S, Raju H. Imaging in malignant thyroglossal duct cyst. Ann Indian Acad Otorhinolaryngol Head Neck Surg 2020;4:57-60 |
How to cite this URL:
Shankaralingappa A, Patil AR, Nandikoor S, Nair S, Raju H. Imaging in malignant thyroglossal duct cyst. Ann Indian Acad Otorhinolaryngol Head Neck Surg [serial online] 2020 [cited 2023 Apr 2];4:57-60. Available from: https://www.aiaohns.in/text.asp?2020/4/2/57/309784 |
| Introduction | |  |
Thyroglossal duct cyst (TGDC) is the most common congenital anomaly in the development of the thyroid gland. They are second only to enlarged cervical lymph nodes as the cause of neck mass. Thyroglossal cysts constitute about 7% of midline masses in the neck of adults and 70% of the midline masses in the neck of children.[1] It presents as a painless midline neck swelling that moves with deglutition and protrusion of the tongue. Typical radiological finding is a simple midline cystic swelling in the neck. In general, duct cysts are benign, but 1% of cases may be malignant.[2] Papillary carcinoma is the most common primary TGDC carcinoma.
Here, we present a rare case of a 52-year-old male who presented with a TGDC in the infrahyoid region with features suspicious of neoplasm on Ultrasound (USG) and computed tomogram (CT) and later confirmed to be papillary thyroid carcinoma in the thyroglossal cyst on postoperative histopathology.
| Case Report | | |
A 52-year-old male patient presented with a midline neck swelling. The lesion was insidious to begin with and showed gradual progression for 6 months. There was no history of pain, dyspnea, dysphagia, change in voice, loss of weight, and loss of appetite. There was also no associated hypothyroid/hyperthyroid symptoms. The patient had no prior radiation history.
On examination, there was a solitary midline swelling of size around 4 cm × 6 cm, approximately 2 cm above the suprasternal notch and 1 cm below the hyoid. Swelling was moving upward on deglutition and protrusion of the tongue. The skin over the swelling was normal. No scars/sinus was seen over the swelling. There was no other palpable swelling in the neck. On investigation, the patient was euthyroid.
He was evaluated with ultrasonography of the neck which showed normal thyroid gland with no lesions. A well-defined cystic lesion measuring ~3 cm × 3 cm was noted in midline neck in the suprathyroid region. Thick internal echoes and partial internal septae were noted within cyst. A soft-tissue density measuring ~2.6 cm × 1 cm was noted along the anterior wall with minimal internal vascularity [Figure 1]. Features were suggestive of a complex cyst. | Figure 1: Ultrasound image of midline neck cystic lesion showing peripheral, vascular echogenic area (arrow)
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For further evaluation, contrast enhanced CT of the neck was done which revealed a well-defined midline and left para midline rim enhancing fluid attenuation lesion measuring ~ 3 cm × 4 cm with small enhancing internal soft-tissue components and calcific foci. Cyst was related to the left thyroid lamina with small extension across cartilage. Anteriorly, lesion was abutting strap muscles [Figure 2]a and [Figure 2]b. Normal thyroid gland was seen at the usual location. No enlarged cervical lymph nodes were found. | Figure 2: (a and b) Axial and transverse computed tomogram images showing midline and left paramidline neck cystic lesion with enhancing soft-tissue component within (arrow) and calcific foci (arrowhead)
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Provisional diagnosis of thyroglossal cyst with a secondary neoplastic change, suspicion of papillary thyroid carcinoma was considered due to vascular soft-tissue component with calcificaton.
The patient underwent Sistrunk's procedure. Intraoperative findings revealed a 4 cm × 3 cm lesion over thyroid cartilage with track extending into the hyoid body on the posterior surface. Mass was excised from the cartilage and the tract was traced till hyoid and excised totally along with the body of the hyoid [Figure 3] and [Figure 4]. | Figure 4: Gross image showing resected cyst (arrow) and body of hyoid bone (arrowhead)
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Postoperative histopathological gross examination showed a cyst with thick internal content and two soft to firm papillary excrescences in the periphery [Figure 5]. On microscopy, the papillae were lined by single layer of tumor cells with nuclear enlargement and crowding without pleomorphism. Few tumor cells showed nuclear grooving. Occasional psammoma bodies were seen. Cystic area showed thyroid follicles [Figure 6],[Figure 7],[Figure 8]. | Figure 5: Gross image of cyst: Cut surface showing papillary excrescences attached to the cyst wall periphery (arrow)
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 | Figure 6: Microscopic whole section image showing cyst wall (arrowhead) with focal papillary structures (arrow)
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 | Figure 7: Narrow to broad papillae with fibrovascular core (arrow). (Scanner view ×4 H and E)
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 | Figure 8: (a and b) Papillae lined by single layer of tumor cells which are columnar and show nuclear enlargement, overlapping, and overcrowding (arrowhead). Occasional tumor cells show intranuclear pseudoinclusions (arrow) (×40, high power view, H and E)
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The histopathological features were suggestive of papillary carcinoma thyroid in thyroglossal cyst.
The patient was discharged without any complications and advised for follow-up.
| Discussion | | |
The thyroid gland develops from the first pharyngeal arch in midline as endodermal invagination of foregut at the foramen cecum of the tongue. Subsequently, the thyroid descends in front of the pharyngeal gut as a bilobed diverticulum to its adult location below the hyoid bone, anterior to the trachea, and thyroid cartilage by the 7th week. During this migration, the thyroid remains connected to the tongue by a narrow canal, the thyroglossal duct. This duct later disappears. If this duct fails to atrophy it may give rise to a TGDC, tract, fistula, or ectopic thyroid tissue anywhere along the course from the base of the tongue to the thyroid gland.
TGDC can get complicated by superimposed infection, fistulous communication to the skin in case of severe infections with external cyst rupture and rarely may show malignant transformation.
The most common primary TGDC carcinoma is papillary carcinoma (75%–80%), other cancers include mixed papillary, follicular carcinomas (7%), squamous cell carcinoma (5%), follicular carcinoma (1.7%), and Hurthle cell carcinoma and anaplastic carcinoma (0.9%) with latter showing poor prognosis.[3],[4]
The cause of the occurrence of TGDC carcinoma is unclear. The predominate theories proposed are either de novo development from ectopic thyroid tissue found within the TGDC wall which is supported by the absence of a medullary carcinoma in the TGDC as it arises from parafollicular cells or metastases from an occult primary thyroid gland carcinoma.[5],[6] Rarely, metaplasia of columnar lining of the thyroglossal cyst can lead to squamous cell carcinoma even in the absence of thyroid tissue in the ductal epithelial lining.[4]
Thyroglossal cyst carcinoma is more common in third to sixth decades with slight female predominance. Clinical presentation of TGDC carcinoma is usually similar to benign TGDC.
TGDC should be evaluated preoperatively with USG, CT scan, magnetic resonance imaging, and fine-needle aspiration cytology in all cases to aid in diagnosis and to identify normal thyroid gland.
On imaging, benign cyst shows thin, smooth wall and internal fluid attenuation contents. Infected cyst shows thick external wall with rim enhancement, internal septations, high attenuation debris, and may be associated with inflammatory changes of the surrounding soft tissue. The presence of nodularity or vascular soft-tissue mass, calcification is suspicious of neoplastic change.
The management of thyroglossal duct carcinoma depends on the origin of TGDC carcinoma (primary ectopic or metastatic from thyroid gland proper).[7]
In the presence of high-risk factors such as age >45 years, male, size >4 cm, extracapsular invasion, positive nodal status, history of irradiation, the presence of cold nodules in thyroid on thyroid scan, Sistrunk's surgery with total thyroidectomy and modified neck dissection, postoperative radio-iodine ablation with thyroid suppression is considered.[8],[9],[10] In low-risk cases age <45 years, cyst size <4 cm, no extracapsular infiltration, and no neck node, Sistrunk's operation is sufficient but requires regular and close follow-up.[11]
In the present case, the patient did not had associated thyroid nodules or neck nodes or history of radiation. Hence, the patient was advised for regular follow-up.
| Conclusion | | |
TGDC carcinoma is an extremely rare condition and usually an incidental finding. On imaging, benign TGDC is midline, wall is thin, smooth, and internal contents show fluid attenuation. The presence of enhancing solid component is highly suspicious of malignancy. Furthermore, the presence of calcifications is seen in 60% of cases of papillary carcinoma arising from thyroid tissue that corresponds to psammoma bodies on histopathology.[12]
Hence, carcinoma should be considered in TGDC s that have high attenuation values, enhancing solid components and calcifications.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that 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.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
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