An Unlikely Source of Iodine Uptake: A Bronchogenic Cyst Masquerading as Metastatic Thyroid Cancer

Martha Dillon; Rachel Zielinski; Jennifer Worth; Melinda Sanders; Omar Ibrahim; Tarunya Vedere

doi:10.1210/jcemcr/luae042

An Unlikely Source of Iodine Uptake: A Bronchogenic Cyst Masquerading as Metastatic Thyroid Cancer

JCEM Case Rep. 2024 Mar 16;2(3):luae042. doi: 10.1210/jcemcr/luae042. eCollection 2024 Mar.

Authors

Martha Dillon¹, Rachel Zielinski¹, Jennifer Worth², Melinda Sanders³, Omar Ibrahim⁴, Tarunya Vedere⁵

Affiliations

¹ Primary Care Internal Medicine Residency, University of Connecticut Health Center: UConn Health, Farmington, CT 06030, USA.
² Thoracic Surgery, Hartford Healthcare, Norwich, CT 06360, USA.
³ Pathology and Laboratory Medicine, University of Connecticut Health Center: UConn Health, Farmington, CT 06030, USA.
⁴ Interventional Pulmonology, University of Connecticut Health Center: UConn Health, Farmington, CT 06030, USA.
⁵ Endocrine Neoplasia, Endocrinology, University of Connecticut Health Center: UConn Health, Farmington, CT 06030, USA.

Abstract

Radioactive iodine therapy and posttreatment scanning are essential components of differentiated thyroid carcinoma treatment and detection of metastatic disease. False-positive results can be seen on an I-131 scan and are important for clinicians to be aware of. Here, we present a case of a 33-year-old female with follicular thyroid carcinoma who was noted to have an area of moderate uptake in the chest on a whole-body scan following remnant ablation with 30 mCi of I-131 (1.11GBq) concerning for a metastatic hilar lymph node. This was determined to be a mediastinal bronchogenic cyst on surgical pathology. It has been previously proposed that the expression of sodium iodide symporters in some bronchogenic cysts could be the mechanism by which iodine uptake is seen within them. We were able to demonstrate positive immunohistochemical staining for both sodium iodide symporter and the associated paired box gene 8 transcription factor in the cyst sample, which supports the proposed theory.

Keywords: bronchogenic cyst; follicular thyroid carcinoma; radioactive iodine; sodium iodide symporter.

Publication types

Case Reports