Submandibular (Undescended) Ectopic Parathyroid Glands: Elusive to Surgeons and Localization Studies

Abstract

Objectives: High cervical parathyroid adenomas, known as undescended adenomas, occur with a frequency of less than 0.1%, but account for 7% of failed parathyroidectomies. Such cases are scarce in the otolaryngology-head and neck surgery literature. Preoperative localization of undescended adenomas using Technetium 99-c sestamibi scintigraphy (sestamibi) is difficult due to uptake and retention of sestamibi by salivary gland tissue. Methods: We present a review of the literature and two surgeons’ experience involving undescended parathyroid glands complicating the treatment of patients with primary (cases 2,3) and secondary (case 1) hyperparathyroidism. In case 1, a 52-year-old dialysis-dependent male experienced recurrent secondary hyperparathyroidism, requiring three operations over two years to excise all parathyroid glands. The right inferior gland was localized to the submandibular region prior to the final operation. In case 2, two sestamibi–single-photon emission computed tomography scans were proven incorrect when a contralateral undescended adenoma was located in a 54-year-old female at surgical exploration. In case 3, a 49-year-old male with a non-localizing scan underwent a failed neck exploration, complicated by acute pancreatitis postoperatively. The surgeon’s suspicion of an undescended adenoma was confirmed by computed tomography; the adenoma was excised. Results: When sestamibi scans are inconclusive, the contour and symmetry of uptake in and around the submandibular glands should be scrutinized. Thallium-pertechnetate subtraction scanning (TPSS) as a second line modality may be useful. Undescended glands must be considered during an unyielding, thorough parathyroid exploration. Conclusions: Surgeons should consider the possibility of undescended adenoma, and use the aforementioned localization techniques when sestamibi scans are inconclusive.