Graves' disease in ectopic thyroid tissue: a scoping review and a case study

Area of Science:

• Endocrinology
• Surgical Pathology
• Nuclear Medicine

Background:

• Persistent Graves' disease (GD) post-thyroidectomy is uncommon.
• Potential causes include incomplete surgery, ectopic thyroid tissue (ETT), or struma ovarii.

Purpose of the Study:

• To report a novel case of ectopic GD in a large paracardiac mass.
• To perform an in-depth histologic examination of the ectopic thyroid tissue.
• To review existing literature on GD in ETT.

Main Methods:

• Case presentation of a 34-year-old woman with severe thyrotoxicosis post-thyroidectomy.
• Utilized thyrotropin receptor antibodies (TSH-R-Ab) and thyroglobulin levels for diagnosis.
• Employed 99mTc-pertechnetate SPECT/CT for imaging the paracardiac mass.
• Performed surgical removal and histologic examination of the mass.
• Conducted a scoping review of PubMed for GD in ETT cases.

Main Results:

• The patient presented with severe thyrotoxicosis and elevated GD markers despite thyroidectomy.
• SPECT/CT revealed a 13 cm paracardiac mass with tracer uptake.
• Surgical removal of the mass led to euthyroidism.
• Histology showed a distinct Graves' pattern in the ectopic thyroid tissue, differing from the eutopic thyroid.
• Literature review identified 29 ETT cases, with 11 in the mediastinum; 11/29 patients had Graves' eye disease.

Conclusions:

• This is the first report detailing distinct histology between eutopic and ectopic thyroid tissue in Graves' disease.
• Persistent severe GD post-thyroidectomy can indicate a significant ectopic thyroid.
• Ectopic Graves' disease, particularly in the mediastinum, is rare and poses diagnostic difficulties.