Ectopic Parathyroid Adenoma in Piriform Sinus: Case Report and Review of the Literature

Abstract

During routine blood work, a 53-year-old female patient was noted to have asymptomatic hypercalcemia and subsequently found to have hyperparathyroidism. Localization studies for a suspected parathyroid adenoma included 99m Tc Sestamibi scintigraphy, Single Photon Emission Computed Tomography (SPECT)/computed tomography (CT) study, and ultrasound of the neck, which were initially read as negative for parathyroid adenoma. A contrast-enhanced CT scan of the neck was performed to locate the suspected parathyroid adenoma and demonstrated a soft tissue lesion within the right piriform sinus. Flexible fiber optic nasolaryngoscopy revealed a submucosal lesion in the right piriform sinus. Following these findings, the initial 99m Tc Sestamibi scintigraphy and SPECT/ CT were reviewed with confirmation of a focal area of increased activity superior to the right thyroid lobe, corresponding to a nodule in the right piriform sinus that demonstrated increased activity on SPECT/CT. The patient was brought to the operating room for surgical management where a laryngoscope and operating microscope were utilized. The encapsulated lesion was dissected and excised in total. The parathyroid hormone and ionized calcium levels normalized postoperatively. Pathology confirmed a parathyroid adenoma. Parathyroid adenomas are the most common cause of primary hyperparathyroidism. Sixteen percent of parathyroid adenomas can be situated in an ectopic location. Ectopic parathyroid adenomas in the piriform sinus are rare with only a few previously documented cases. We document a rare case of ectopic parathyroid adenoma in the piriform sinus overlooked on initial imaging studies. These lesions can be challenging to localize, however, an understanding of embryology, close scrutiny of possible ectopic locations, and the application of complementary imaging techniques may prove useful for surgeons and clinicians.

Case Report: Nine-year-old with parathyroid adenoma within the piriform sinus

“…99 Tc-sestamibi parathyroid scan combined with single photon emission computed tomography has the highest positive predictive value of the available imaging techniques but can be negative or misleading in patients with a gland in an ectopic position like in our case, a small gland, parathyroid hyperplasia, or multiple parathyroid adenomas ( 13 , 14 ). Our group had previously reported on a series of eight patients with parathyroid adenomas in rare and unusual locations associated with various pharyngeal structures ( 7 ).…”

Resection of an elusive parathyroid adenoma in the aortopulmonary window

“…The prevalence of ectopic and supernumerary parathyroid adenomas is not widely documented in the literature. A case report in 2019 discussed an unusual finding of an ectopic parathyroid adenoma situated in the piriform sinus 2. A 2005 case series of 213 patients with PHPT identified 16% with an ectopic parathyroid adenoma but much depends on the definition of eutopic glands 4…”

“…The most common causes of hypercalcaemia are primary hyperparathyroidism (PHPT) and malignancy. PHPT occurs in all age groups and both sexes but increases in incidence with age mainly due to an increase among women, so that there is an overall 3:1 female predominance 1–3. More than 85% of PHPT patients have a solitary parathyroid adenoma, the remainder a variety of configurations of multiple gland disease or rarely a parathyroid carcinoma.…”

“…More than 85% of PHPT patients have a solitary parathyroid adenoma, the remainder a variety of configurations of multiple gland disease or rarely a parathyroid carcinoma. Most parathyroid disease is located in the neck in a eutopic position, with supernumerary or ectopically located parathyroid gland adenomas being rare 1–3. Surgical resection of the hyperfunctioning parathyroid is the only definitive cure but this can be challenging when localisation investigations are negative or misleading.…”