Ectopic thyroid nodes in the mediastinum – report of two cases

Abstract

Introduction Ectopic thyroid is a rare anomaly characterized by presence of thyroid tissue outside its normal location, which could be the consequence of developmental abnormality, sequestration of thyroid nodes from nodal thyroid goiter or mechanical implantation of thyroid tissue after resection or trauma. Ectopic thyroid is commonly incidentally detected and causes differential diagnostic dilemma towards the neck and mediastinal tumors. The object of this report was to present two types of ectopic thyroid nodes located in the upper mediastinum, incidentally discovered by computed tomography (CT).

Outline of cases A hyperdense nodular lesion was found in the anterior upper mediastinum in a 42-year-old woman with adenocarcinoma of the esophagogastric junction in whom CT was performed due to staging purposes. Metastatic left supraclavicular lymph node was considered in the differential diagnosis. However, as the node was located in front of the neck fascia and just below the thyroid gland and showed similar density to thyroid tissue, the diagnosis of accessory thyroid gland was made, which was later confirmed by multiple repeated CT scans during the two-year follow-up period. In a 52-year-old woman presenting with intermittent chest pain and cough, contrast-enhanced CT scan revealed nodal thyroid goiter and three nodes of similar CT texture, located in the upper mediastinum, below the thyroid gland. Accordingly, the diagnosis of parasitic mediastinal goiter thyroid nodes was made.

Conclusion Ectopic thyroid nodes are presented by CT as well-circumscribed nodes of the same density as the thyroid gland, typically located anteriorly in the upper mediastinum.

Keywords: thyroid gland; computed tomography; ectopic thyroid nodes; accessory thyroid gland