Ektopes Gewebe der Schilddrüse und der Nebenschilddrüsen

Abstract

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.

Rare concurrence of ectopic intrathyroidal parathyroid gland and papillary thyroid carcinoma within a thyroid lobe

“…During embryogenesis, the inferior parathyroid glands may migrate to variable anatomic locations such as superior mediastinum, carotid sheath, thymus, and even thyroid. [1,2] The incidence of ETPG within the thyroid parenchyma was reported to be 0.2% from a large anatomical series study. [3] Compared with ETPG, ectopic intrathyroidal parathyroid lesions, such as adenoma or carcinoma, can be more easily diagnosed through classical symptoms of hyperparathyroidism, imaging examinations, or fine needle aspiration cytology.…”

The value of ultrasound in combination with 99mTc-MIBI imaging department of ultrasound medicine, for the diagnosis of ectopic parathyroid glands in the thyroid gland in patients with secondary hyperparathyroidism

“…Parathyroid glands during embryonic development, the inferior parathyroid glands can migrate to various anatomical locations, such as the superior mediastinum, carotid sheath, thymus, and even the thyroid gland. [6,7] In a review of 56 autopsies performed at the Federal University of São Paulo, Brazil, at least one ectopic parathyroid gland was found in 42.8% of cases, and the ectopic sites were predominantly in the mediastinum and thymus (19.6%), the subperitoneal space of the thyroid (12.5%), and the parenchyma of the thyroid (5.4%). [8] The incidence of ETPG has been reported in the literature to range from 0.7% to 3.4%, and 70.6% occur in the right lobe of the thyroid gland, with a prevalence in the lower extreme 1/3.…”

The magic mirror: a novel intraoperative monitoring method for parathyroid glands

“…The rate of ectopic PGs attained is 35% due to abnormal migration during early development ( 34 ). The ectopic PGs may be present in the anterior mediastinum, tracheoesophageal groove or retroesophageal region, the retropharyngeal region, the axilla, along the course of the vagus nerves, near the carotid sheath, in the thymus, and within the thyroid gland ( 35 ). Furthermore, the tiny volume and the similar appearance to the adipose tissue and the lymph nodes lead to an increased difficulty for surgeons to identify ( 2 ).…”