Can Medullary Thyroid Carcinoma Arise in Thyroglossal Duct Cysts? A Search for Parafollicular C-cells in 41 Resected Cases

Clinical Characteristics and Prognosis of Infants and Children <3 Years of Age With Thyroglossal Duct Cyst Complicated With a Parapharyngeal Mass: A Case Series Study

Thyroglossal duct cysts (TGDCs) are congenital and developmental abnormalities in infants and young children. This retrospective case series study examined the characteristics of 7 patients <3 years (mean age, 1.9 years) with TGDC complicated with a parapharyngeal mass treated at one hospital between January 2019 and 2022. Four patients had a painless mass around the neck, 2 had a painless mass associated with snoring, and 1 presented repeated swelling and pain. B-ultrasound suggested 6 cases of TGDC and 1 possible lymphangioma. All patients were treated with Sistrunk surgery to remove the TGDC. Six patients had no cyst recurrence during follow-up (6 months to 2 years). In conclusion, TGDC complicated with a parapharyngeal mass has complex and variable clinical manifestations. Completely removing the cyst while sparing thyroid cartilage and surrounding vascular and neuroanatomical structures is important to avoid complications. The patients are likely to be free from recurrence after surgery.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: The Neck and Lymph Nodes, Metastasis, and Melanocytic Tumors

The changes made in the fifth edition of the WHO Classification of Head and Neck Tumors demonstrate the recent diagnostic, histopathological, and molecular advances in the field, and this updated information will hopefully lead to improved and standardized tumor subtyping. This review summarizes the changes related tumors and tumor-like lesions of the neck and lymph nodes (Chapter 11), metastasis to the head and neck region (Chapter 15), and melanocytic tumors (Chapter 10).

Thyroid tissue outside the thyroid gland: Differential diagnosis and associated diagnostic challenges

The presence of thyroid tissue outside of the thyroid gland may occur in various clinical settings and anatomic locations and includes both benign and malignant differential diagnoses. Some of these entities include thyroglossal duct cyst, lingual thyroid, parasitic nodule, thyroid tissue within a lymph node and struma ovarii. In routine daily practice, these entities do pose diagnostic challenges for the pathologists. Differential diagnostic considerations depend largely on the location of lesion and the histologic features. A definitive diagnosis may remain unclear in some cases while knowledge is still evolving in others i.e., incidentally detected bland appearing thyroid follicles in a lateral neck lymph node. This article aims to elaborate on the various entities characterized by thyroid tissue outside of the thyroid gland, both benign and malignant, and the relevant differential diagnostic considerations.

[Ectopic tissue of the thyroid gland and the parathyroid glands]

Ectopic thyroid tissue results from developmental defects of the early stages of thyroid embryogenesis, in which the median thyroid anlage descends from the floor of the mouth to its final pre-tracheal position. The most common sites of ectopic thyroid tissue are accordingly in the area of the floor of the mouth and in the course of the thyroglossal duct. Rare localizations are intrathoracic (mediastinal, cardiac, pulmonary) and sub-diaphragmatic (including the adrenals, liver, gall bladder, and gastrointestinal tract). The most important differential diagnosis of ectopic thyroid is metastasis of differentiated thyroid carcinoma.By contrast, the term parathyroidectopy is not uniformly defined. Usually, the cervical-central localizations are referred to as "positional variants" (with the exception of the maxillary sinus and high parapharyngeal), whereas the cervical-lateral localizations (carotid sheath, vagus nerve) and those below the brachiocephalic and mediastinal positions (extraligamentary, aortopulmonary window, paravagal) and other rare localizations are classified as "ectopic parathyroid tissue". Parathyroidectomy is very common (in autopsy studies in 28 to 42.8% of all humans). In the context of primary hyperparathyroidism (pHPT), there is a prevalence of 6.3 to 16% of ectopic hyperfunctional parathyroid tissue (predominantly adenomas), which play an important role in the surgical treatment of pHPT.