Parathyroid adenoma localized in the lower neck in a patient with lingual thyroid demonstrated with Tl-201/Tc-99m pertechnetate scintigraphy

The authors describe a patient with a known lingual thyroid and hypothyroidism in whom hyperparathyroidism developed. A large parathyroid adenoma was detected using Tl-201 scintigraphy, whereas ultrasonography and computerized tomography failed to detect the lesion. In this patient, the thyroid remained in its original embryonal site in the pharyngeal floor, while the parathyroid glands migrated normally to their final anatomical location. In adult life, both glands showed abnormal function: the thyroid gland was hypofunctioning, and the parathyroid gland was hyperfunctioning due to parathyroid adenoma. A lingual thyroid is often associated with hypothyroidism. However, the association of a parathyroid adenoma in a normally located parathyroid gland, with an ectopic thyroid is uncommon. Tl- 201/Tc-99m scintigraphy was able to distinguish between the different locations of the two structures and to establish the diagnosis.