A Unique Case of Thyroid Dysgenesis in a Neonate

Double tongues

A 1-year-old Chinese boy presented with a mass at the base of his tongue with dysphagia. The distal end of the lesion could be put out of his mouth, making a "double tongue" appearance. Before surgery, serum test showed euthyroidism. Thyroid scintigraphy showed good function of the orthotopic thyroid, yet no uptake by the lesion, excluding ectopic thyroid. En bloc resection was performed. Histopathology demonstrated aberrant salivary tissues. Our case indicates that differential diagnosis between ectopic salivary tissues and ectopic thyroid should be borne in mind when treating patients with double tongues.

A high prevalence of dual thyroid ectopy in congenital hypothyroidism: evidence for insufficient signaling gradients during embryonic thyroid migration or for the polyclonal nature of the thyroid gland?

BACKGROUND

Thyroid ectopy results from the failure of the thyroid precursor cells to migrate from the primordial pharynx to the anterior part of the neck. Most ectopic thyroids are revealed by congenital hypothyroidism and present as a single round mass at the base of the tongue, with no other thyroid tissue. However, some cases have dual ectopy, with part of the tissue having partially migrated. We hypothesized that this occurs more frequently than previously reported.

METHODS

To determine the prevalence of dual ectopy, we reviewed the pertechnetate scintigraphies of 81 patients with congenital hypothyroidism from thyroid ectopy diagnosed between 2002 and 2011 at our institution.

RESULTS

We report a series of seven cases (9%) of dual ectopy, representing an incidence ranging from 1:50,000 to 1:70,000.

CONCLUSIONS

Almost one in 10 cases with congenital hypothyroidism due to thyroid ectopy has dual ectopy. This suggests that two populations of cells diverged at an early stage of development, which may arise from insufficient signaling gradients in surrounding tissues during early organogenesis or may indirectly support the polyclonal nature of the thyroid.