Dual thyroid ectopia: A pictorial case series and review of literature

Abstract

Ectopic thyroid (ET) is a developmental anomaly of the thyroid gland with the presence of thyroid tissue at sites other than the normal cervical location anterior to second and third tracheal ring due to abnormal migration of the gland. It may be found along the path of descent of the developing thyroid primordium from the foramen caecum to the isthmus of the thyroid and up to the base of the diaphragm. Dual thyroid ectopia, where ET tissue is simultaneously present at two different abnormal locations, is a very rare developmental defect. Only a few cases have been reported worldwide. ET is predominantly seen in females and during puberty when the hormonal demand is high. Patients with ET may remain asymptomatic or present with swelling in the neck, symptoms such as dysphagia, dysphonia, dyspnea, and features of hypothyroidism. The diagnosis is usually made on clinical examination, laboratory tests, imaging studies, and cytology. Careful clinical evaluation is essential as ET may be the only functioning thyroid tissue. Thyroid scintigraphy is an important imaging tool and the gold standard for the diagnosis of ET tissue, as it has high sensitivity and specificity. Early and accurate diagnosis of ET is essential to start hormone replacement and avoid unnecessary surgery. The authors report here a series of four patients with dual ET tissue, diagnosed on thyroid scintigraphy.

Accessory Thyroid Tissue Detected Using 131I SPECT/CT Imaging

“…[1][2][3] Ectopic thyroid tissue could be located anywhere from the foramen caecum of the tongue to the diaphragm base, although the majority is in the lingual and sublingual location. [2][3][4][5] A number of rare sites of ectopy has been reported, including within organs of the thorax, abdomen, and pelvis, as well as structures such as the pituitary gland and vertebral body. 4,6,7 Dual ectopic thyroid is considered a rarer form of thyroid ectopia characterized by the presence of both an orthotopic and ectopic gland, with 70% of ectopic thyroid cases lacking thyroid tissue at the orthotopic pretracheal site.…”

“…The axial (G) and coronal (H) fusion images further precisely localized the ectopic thyroid to the region of the embryonic thyroglossal duct. Ectopic thyroid tissue is caused by disruption to thyroid migration during embryonic development, resulting in thyroid tissue ectopic to the orthotopic thyroid bed anterolateral to the second to fourth tracheal rings [1][2][3]. Ectopic thyroid tissue could be located anywhere from the foramen caecum of the tongue to the diaphragm base, although the majority is in the lingual and sublingual location [2][3][4][5].…”

“…Ectopic thyroid tissue is caused by disruption to thyroid migration during embryonic development, resulting in thyroid tissue ectopic to the orthotopic thyroid bed anterolateral to the second to fourth tracheal rings [1][2][3]. Ectopic thyroid tissue could be located anywhere from the foramen caecum of the tongue to the diaphragm base, although the majority is in the lingual and sublingual location [2][3][4][5]. A number of rare sites of ectopy has been reported, including within organs of the thorax, abdomen, and pelvis, as well as structures such as the pituitary gland and vertebral body 4,6,7.…”