Thyrotoxicosis due to ectopic lateral thyroid tissue presenting 5 years after total thyroidectomy

Area of Science:

• Endocrinology
• Surgical Pathology

Background:

• Graves disease is a common cause of hyperthyroidism.
• Total thyroidectomy is a standard treatment for severe Graves disease.
• Recurrent hyperthyroidism post-thyroidectomy warrants investigation for alternative causes.

Observation:

• A patient with a history of Graves disease presented with recurrent hyperthyroidism 5 years after total thyroidectomy.
• Diagnostic imaging, including radioactive iodine scan, ultrasonography, and CT, identified ectopic thyroid tissue in the left mid-neck.
• Surgical excision and histopathologic examination confirmed benign ectopic thyroid tissue without malignancy.

Findings:

• Ectopic thyroid tissue was identified as the sole cause of thyrotoxicosis.
• Histopathology revealed chronic lymphocytic infiltrate, focal thyroid hyperplasia, and papillary infoldings, consistent with benign tissue.
• No evidence of malignancy was found in the excised ectopic thyroid tissue.

Implications:

• This case represents the first reported instance of ectopic benign thyroid tissue causing hyperthyroidism post-thyroidectomy.
• Clinicians should consider ectopic benign thyroid tissue in the differential diagnosis for persistent hyperthyroidism in patients who have undergone thyroidectomy.
• Prompt diagnosis and management of ectopic thyroid tissue can resolve thyrotoxicosis symptoms.