Malignant degeneration of thyroglossal duct cysts: Clinical aspects, imaging findings and management: Case series

INTRODUCTION AND IMPORTANCE

Thyroglossal duct cysts (TDCs) are congenital anomalies that can rarely undergo malignant transformation, with approximately 1 % of operated TDCs demonstrating malignant degeneration. Therapeutic management and follow-up methods are still controversial subjects.

CASE SERIES PRESENTATION

We report 3 cases of a papillary carcinoma of thyroid occurring in a thyroglossal duct cyst. The diagnosis was suspected preoperatively in 2 patients, hence the indication of frozen section examination. All patients underwent Sistrunk procedure associated with total thyroidectomy and central neck dissection. Concomitant papillary thyroid carcinoma was found in 2 patients. A complementary treatment by radioactive iodine 131 with frenetic hormone therapy was undertaken in all the cases. The follow-up showed no recurrence.

CLINICAL DISCUSSION

The clinical presentation of thyroglossal duct cyst carcinoma is often nonspecific, posing challenges in early diagnosis. The chosen treatment strategy, involving the Sistrunk procedure, total thyroidectomy, and central neck dissection, along with adjuvant therapy using radioactive iodine 131 and frenetic hormone therapy, was effective in preventing recurrence.

CONCLUSION

The management of degenerated TDC is based on a multidisciplinary approach. Papillary carcinomas of TDC generally have a good prognosis.

Synchronous carcinoma of thyroglossal duct cyst and native thyroid gland

The unobliterated portion of embryological thyroglossal duct may present as cystic swelling later in life and may contain functional thyroid follicles. This cyst requires excision along with the entire thyroglossal duct remnant and adjacent portion of hyoid bone. At times, the excised specimen could demonstrate a focus of carcinomatous change inside the cyst wall. Very rarely, this thyroglossal duct cyst carcinoma could be associated with malignancy of native thyroid gland. This case report illustrates an interesting case of synchronous carcinoma of thyroglossal duct cyst and native thyroid gland. It also sheds light on the controversies related to the pathophysiology of such association and the dilemmas surrounding the management of thyroglossal duct cyst carcinoma, with or without concurrent carcinoma of thyroid gland.

Approach to FNA of Thyroid Gland Cysts

Fine needle aspiration is a well-known procedure for the diagnosis and management of thyroid lesions, representing the first diagnostic tool for the definition of their nature. In clinical practice, a thyroid nodule can be classified as solid, cystic, and partially cystic based on its internal components. Different thyroid imaging reporting systems and cytologic diagnostic systems have focused their attention on solid nodules, which are more frequently linked with a malignant outcome. In fact, numerous papers demonstrated that nodules with microcalcifications, a taller-than-wide shape, hypoechogeneity, and irregular margins, are more likely to be malignant on histology. Nevertheless, according to the literature, the risk of malignancy in a partially cystic thyroid nodule ranges between 3.3 and 17-5%, including, for instance, the possible diagnosis of a cystic papillary thyroid carcinoma and other malignant entities. Therefore, in the current review article, we are going to discuss the approach to thyroid cystic lesions on fine needle aspiration cytology.

Evidence and controversies in management of thyroglossal duct cyst carcinoma

PURPOSE OF REVIEW

The aim of this study was to analyse the rational of the possible therapeutic approaches to thyroglossal duct cyst carcinomas (TGDCCa), especially in consideration of their potential airway involvement, discussing the most debated issues concerning employment of thyroidectomy, neck dissection and adjuvant treatments.

RECENT FINDINGS

The literature is unanimous in defining the Sistrunk procedure as the baseline of surgical treatment of TGDCCa, and in equating the vast majority of thyroid-like TGDCCas to classic thyroid cancers from a biological point of view, while the rarer squamous cell carcinomas seem to behave more aggressively. Thyroidectomy, neck dissection and radioactive iodine treatment are considered for high-risk lesions, with the addition of customized partial resection of laryngeal cartilages when airway involvement is encountered. Furthermore, the analysis of thyroid mutational markers has promise for accurate prevision of more aggressive clinical behaviours.

SUMMARY

Even if rare, clinicians should be aware of TGDCCa due to the possibility of incidental diagnosis and, in the case of more advanced clinical scenarios, for its potential airway involvement. Sistrunk procedure combined with thyroidectomy, neck dissection and adjuvant therapy provide excellent results in high-risk patients. Additional study of pathological thyroid markers in TGDCCa is desirable to allow more individualized treatments.