Presentation
Congenital hypothyroidism on newborn screening. TSH level=710 mIU/L (normal range: 0.35-4.94).
Patient Data
36 MBq of Tc-99m pertechnetate was administered intravenously and planar images in anterior, left anterior oblique, and right anterior oblique projections were acquired 20 minutes post injection.
Well-circumscribed area of radiotracer concentration in the posterior floor of the mouth representing lingual thyroid. No radiotracer uptake is seen in the anatomical region of the thyroid gland. Thyroid uptake function=1% (normal: 0.4‒4%).
Case Discussion
Scan finding are suggestive of ectopic lingual thyroid with no evidence of radiotracer uptake in the anatomical region of the thyroid gland. Thyroid uptake function is within normal limits and correlation with laboratory result of elevated TSH level, is suggestive dyshormonogenesis in the ectopic thyroid tissue.