Ectopic thyroid tissue in the lower neck with a coexisting normally located multinodular goiter. Brief literature review

Abstract

Ectopic thyroid tissue in the lower neck with a coexisting normally located multinodular goiter is a rare entity. We present a 27-year old asymptomatic woman with a recent history of a painless mass in the left side of her lower neck. Thyroid function tests were normal. An ultrasound of her neck showed a multinodular goiter and a 3.4 cm solid mass in the left lower cervical area. These findings were confirmed by an MRI scan of her neck. The Tc99m Pertechnetate scan showed the presence of a functioning area under the left lobe of the thyroid gland. The patient underwent surgery. The cervical mass was identified as a structure separate from the left lobe of the thyroid, without any attachments to the body of the gland and was uniformly resected. A subtotal thyroidectomy was also performed. The histology revealed that the separate structure represented ectopic thyroid tissue. The patient had an uneventful postoperative recovery, subsequent to which she was euthyroid and had normal calcium levels.

Ectopic Thyroid Presenting as a Submandibular Mass

“…Ectopic thyroid is defined as thyroid tissue not anterolateral to the second, third and fourth tracheal rings, in the midline [1,3,5,9]. It is the most common form of thyroid dysgenesis, accounting for 48-61% of all cases [6].…”

“…It is the most common form of thyroid dysgenesis, accounting for 48-61% of all cases [6]. Although its incidence is not known, studies on necropsy suggest that 7-10% of the adults can be asymptomatic carriers of thyroid tissue in the thyroglossal duct path [5,6,9].…”

“…Ectopic thyroid tissue usually occurs in the midline, from the foramen caecum to the mediastinum [1,5,7,9] as a result of abnormal median migration and is rarely present lateral [1,10]. A lingual location is most common, accounting for 90% of the reported cases [1,3,5,6,[8][9][10].…”

“…Embryologically, the thyroid gland is derived from a median cluster of cells and from two lateral cell clusters [1][2][3][4][5]. The median portion produces the largest part of the thyroid parenchyma while the lateral portions are derived from the fourth pharyngeal pouch accounting for 1-30% of the total thyroid weight [1,5].…”

“…The median portion produces the largest part of the thyroid parenchyma while the lateral portions are derived from the fourth pharyngeal pouch accounting for 1-30% of the total thyroid weight [1,5]. A number of anomalies can develop during thyroid formation [2,5], including ectopia of the thyroid tissue, a rare entity [3,[5][6][7], which may or may not coexist with a normal thyroid gland [3,5,6].…”