Category: Thyroid

Monitor: 1

1 - Recurrence of Graves' disease in ectopic thyroid tissue in an unusual submandibular location

Saturday, Apr 27
10:00 AM – 10:30 AM

Objective :

Ectopic thyroid tissue can be found  as a component of thyroglossal duct cysts, and anywhere along the course of the thyroglossal duct. The most frequent location is the base of the tongue or anterior neck (90% of cases), with rare (1-3%) lateralization in the neck. Submandibular location of thyroid tissue is extremely rare. Ectopic thyroid tissue behaves like a normal thyroid gland, but  autoimmunity  in ectopic tissues is rare.


Methods : N/A


Results : N/A


Discussion :

We saw a 29-year-old female  with Graves’ disease and who had total thyroidectomy with intolerance to methimazole due to persistent hives and angioedema with propylthiouracil 18 months ago. Radioactive iodine ablation therapy was not done because she was planning pregnancy. She started on levothyroxine 100 mcg after surgery and did well for  6 months. Next she presented with an enlarging lateral neck mass  with clinical signs of hyperthyroidism.  Physical exam: an anxious female with thyroidectomy scar tissue in the lower anterior neck,  no palpable thyroid tissue in the thyroid bed. There was a palpable, non-tender mass 3 cm in diameter in the anterior lateral neck.  Thyroid stimulating hormone (TSH) was <0.006 uIU/ml (normal, 0.45 - 4.5 uIU/mL) and free thyroxine (FT4) was 1.69 ng/dL (normal: 0,82 to 1.77 ng/dL). Despite reduction of the levothyroxine dose multiple times, thyroid function tests were consistent with thyrotoxicosis: TSH <0.006 mcIU/ml, FT4 2.38 ng/dL. Thyroid-stimulating immunoglobulin  level was 5.79 IU/L (normal, 0.55 IU/L). With suspicion of recurrent Graves’ disease, levothyroxine was discontinued, and she was treated with methimazole. FT4 improved to 1.23 ng/dL. Computerized tomography with intravenous contrast  showed a lobulated mass (3.6 cm x 2.8 cm x 2.6 cm)  in the right anterior lateral neck extending to the hyoid bone and invading the right parapharyngeal soft tissues. Fine needle aspiration and core biopsy of the mass showed normal thyroid follicle cells with no signs of malignancy.   Radioactive iodine thyroid uptake and scan with I-123  showed an iodine avid right lateral neck mass. Radioactive iodine ablation  with 20 mCI I-131 of the neck mass was done. TSH was elevated at 15.77 uIU/ml 1 month after ablation and she was started on  levothyroxine.


 


Conclusion : In this patient,  Graves’ disease with elevated TSI level caused submandibular ectopic tissue to grow and become clinically symptomatic. Clinicians should be aware  of this unusual location for ectopic thyroid tissue in the submandibular region. This case highlights the rare occurrence of autoantibodies stimulating ectopic thyroid tissue. This location of ectopic thyroid tissue should be considered in recurrent Graves’ disease.

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Sevil Aliyeva

PGY4 endocrinology fellow
Medstar Union Memorial Hospital Endocrinology
Ellicott, Maryland

First year endocrinology fellow in Medstar Union Memorial Hospital Endocrinology and Metabolism Fellowship. Graduated from Azerbaijan Medical University in 2005. Completed Internal Medicine residency program in Capital Health Regional Medical Center in 7/2018. I am board certified internal medicine physician in USA.

Pamela R. Schroeder

Program Director, Endocrinology and Metabolism Fellowship
Union Memorial Hospital
Baltimore, Maryland

Program Director

Malek Cheikh

Faculty
Medstar
Baltimore, Maryland

Endocrinologist, faculty in the MedStar system. Interested in metabolic bone disorders, diabetes and thyroid disorders

Sevil Aliyeva

PGY4 endocrinology fellow
Medstar Union Memorial Hospital Endocrinology
Ellicott, Maryland

First year endocrinology fellow in Medstar Union Memorial Hospital Endocrinology and Metabolism Fellowship. Graduated from Azerbaijan Medical University in 2005. Completed Internal Medicine residency program in Capital Health Regional Medical Center in 7/2018. I am board certified internal medicine physician in USA.