An unexpected finding from a submental mass.

This case describes a fit and well 17-year-old male who underwent surgical resection of a longstanding, painless, right lateral neck swelling. Believed to be either a vascular malformation, ranula or enlarged sublingual gland from pre-operative MR studies, histopathological examination of the mass revealed it as normal thyroid tissue. Post-operative imaging confirmed the absence of any remaining thyroid tissue. Hypothyroidism was confirmed with subsequent thyroid function tests. Interestingly, a "thyroid storm" which presented unknowingly during the surgical removal of the lesion did not trigger suspicion that thyroid tissue was being handled at the time. Normal, ectopic thyroid tissue in the lateral neck is rare but should be considered a differential diagnosis for neck lumps, particularly if it also presents as an intraoral swelling, as in this case. The presence of the orthotopic thyroid gland should be confirmed with diagnostic imaging prior to surgical excision of unknown neck masse.