Ectopic Parathyroid Tissue Research Articles

Imaging Recommendations for Diagnosis and Management of Primary Parathyroid Pathologies: A Comprehensive Review.

Parathyroid pathologies are suspected based on the biochemical alterations and clinical manifestations, and the predominant roles of imaging in primary hyperparathyroidism are localisation of tumour within parathyroid glands, surgical planning, and to look for any ectopic parathyroid tissue in the setting of recurrent disease. This article provides a comprehensive review of embryology and anatomical variations of parathyroid glands and their clinical relevance, surgical anatomy of parathyroid glands, differentiation between multiglandular parathyroid disease, solitary adenoma, atypical parathyroid tumour, and parathyroid carcinoma. The roles, advantages and limitations of ultrasound, four-dimensional computed tomography (4DCT), radiolabelled technetium-99 (99mTc) sestamibi or dual tracer 99mTc pertechnetate and 99mTc-sestamibi with or without single photon emission computed tomography (SPECT) or SPECT/CT, dynamic enhanced magnetic resonance imaging (4DMRI), and fluoro-choline positron emission tomography (18F-FCH PET) or [11C] Methionine (11C -MET) PET in the management of parathyroid lesions have been extensively discussed in this article. The role of fluorodeoxyglucose PET (FDG-PET) has also been elucidated in this article. Management guidelines for parathyroid carcinoma proposed by the American Society of Clinical Oncology (ASCO) have also been described. An algorithm for management of parathyroid lesions has been provided at the end to serve as a quick reference guide for radiologists, clinicians and surgeons.

Robot-Assisted Thoracoscopic Resection of Ectopic Parathyroid Tissue in Mediastinum: A Scoping Review.

Ectopic parathyroid tissue in the mediastinum represents a rare and potentially serious clinical entity with challenging diagnostic and surgical management. The main surgical approach for this issue is open thoracotomy, which is a safe technique but carries risks and complications associated with such as extensive surgery. The purpose of this study is to demonstrate robotic thoracic surgery as an alternative and potentially advantageous method to treat patients with ectopic parathyroid adenomas compared with open and video-assisted thoracoscopic surgery approaches. A total of 13 reports in the literature were identified that provided details in terms of complications, surgical approach, and results of minimally invasive surgical resection of mediastinal ectopic parathyroid tissue.

SAT187 A Case Of CDC73 Mutation Related Primary Hyperparathyroidism With Ectopic Parathyroid Hyperplasia

Abstract Disclosure: T. Wu: None. N. Dhir: None. M. Bollineni: None. Introduction: Primary hyperparathyroidism is the most common cause of hypercalcemia, and most cases are sporadic. However, in 5-10% cases, it may occur as a syndromic and hereditary disease, like Multiple endocrine neoplasia type 1, type 2A, type 4, or CDC73 mutation related hereditary benign or malignant hyperparathyroidism. In patients with severe or early onset primary hyperparathyroidism, screening for genetic etiology should be considered. Case Presentation: A 35-year-old woman with a medical history of hypertension, kidney stones, and post-operative hypothyroidism presented to the endocrinology clinic due to recurrent hyperparathyroidism. She initially had a parathyroidectomy in 2008 and her calcium corrected at that time. She was again diagnosed with hypercalcemia due to primary hyperparathyroidism in 2021. She underwent re-exploration and had a right thyroid lobectomy with removal of three parathyroid glands. Her PTH was still 309 pg/mL (9-77 pg/mL) and calcium was 11.2 mg/dL (8.6-10.5 mg/dL), and she was started on Cinacalcet. The patient continued to have elevated calcium, bone pain, fatigue, and constipation. A 4D CT scan was ordered, which localized activity to a 1.5 cm arterial enhancing nodule in the anterior mediastinum, with intrathymic location. She underwent right video-assisted thoracoscopic total thymectomy with en bloc and the nodule was found to be ectopic parathyroid tissue. Post-operatively, her calcium normalized to 8.6 mg/dL and PTH was undetectable. She underwent genetic testing due to her recurrent hyperparathyroidism, which showed a CDC73 mutation. She is currently on calcitriol and calcium supplements, and serum calcium has been maintained in the low-normal range. Discussion: The CDC73 gene encodes a protein called parafibromin, which acts as a tumor suppressor, prohibiting cells from proliferating. Mutations in this gene are linked to jaw-tumor syndrome, familial isolated primary hyperparathyroidism (FIHP), and parathyroid carcinoma. These three CDC73-related disorders are clinically overlapping and inherited in an autosomal dominant manner. Biallelic mutations of the CDC73 gene are associated with a high risk of parathyroid cancer since the parafibromin protein is usually absent in parathyroid carcinoma and occasionally in atypical adenomas. FIHP tends to have a more severe clinical presentation with earlier onset (younger than 45 years). Additionally, patients with CDC73 related disorders are more prone to developing ossifying fibroma(s) of the jaw, uterine tumors, and various renal lesions. In summary, this case highlights the diagnostic and therapeutic challenges in a patient with persistent primary hyperparathyroidism after a failed second surgery. Genetic testing is vital for early detection, surveillance, and familial genetic counseling in patients with CDC73 related disorders. Presentation: Saturday, June 17, 2023

BROWN TUMOR OF PRIMARY HYPERPARATHYROIDISM ASSOCIATED WITH ECTOPIC PARATHYROID TISSUE

This study presents an unusual case of primary hyperparathyroidism with a brown tumor caused by ectopic parathyroid tissue within the mediastinum. A 48-year-old male was admitted, complaining of a painful and hemorrhagic swelling in the anterior mandible, of unknown duration. The patient's medical history was uneventful. Spiral computed tomography revealed well-defined multilocular radiolucencies located within the anterior and body of the mandible, bilateral mastoid processes, and temporal bone, causing significant cortical expansion and thinning. An incisional biopsy of the anterior mandible showed a central giant cell lesion, and laboratory exams detected high values of parathormone, alkaline phosphate, and calcium. Further sestamibi-SPECT parathyroid scintigraphy was carried out and hyperfunctioning ectopic parathyroid tissue within the mediastinum region was detected. The patient was referred to an endocrinologist and is being prepared for thoracic surgery for analysis of the ectopic parathyroid tissue. This study presents an unusual case of primary hyperparathyroidism with a brown tumor caused by ectopic parathyroid tissue within the mediastinum. A 48-year-old male was admitted, complaining of a painful and hemorrhagic swelling in the anterior mandible, of unknown duration. The patient's medical history was uneventful. Spiral computed tomography revealed well-defined multilocular radiolucencies located within the anterior and body of the mandible, bilateral mastoid processes, and temporal bone, causing significant cortical expansion and thinning. An incisional biopsy of the anterior mandible showed a central giant cell lesion, and laboratory exams detected high values of parathormone, alkaline phosphate, and calcium. Further sestamibi-SPECT parathyroid scintigraphy was carried out and hyperfunctioning ectopic parathyroid tissue within the mediastinum region was detected. The patient was referred to an endocrinologist and is being prepared for thoracic surgery for analysis of the ectopic parathyroid tissue.

Retrosternal parathyromatosis in a patient with prior total parathyroidectomy

Abstract Parathyromatosis is a rare cause of recurrent primary hyperparathyroidism that often follows surgical removal of the parathyroid gland. Foci of parathyromatosis are most commonly found in the neck, mediastinum, and sites of autotransplantation. A 36-year-old male with renal failure and prior parathyroidectomy presented with generalized bone pain, for which laboratory investigations revealed hyperparathyroidism. Preoperative coil localization was utilized followed by thoracoscopy using fluoroscopy for resection of ectopic parathyroid tissue. The specimen was sent to histopathology, which revealed multiple nodules of hypercellular parathyroid tissue, consistent with the diagnosis of parathyromatosis. Parathyromatosis is a rare cause of recurrent hyperparathyroidism, with surgical removal being the only curative option. Follow-up is essential as it can commonly recur.

Primary hyperparathyroidism related to ectopic thymic parathyroid tissue: about two cases

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Abstract #1373163: A Rare Case of Ectopic Parathyroid Adenoma in the Left Axillary Region

A parathyroid adenoma is a benign neoplasm that arises from parathyroid parenchymal cells. Parathyroid adenomas are the most common cause of primary hyperparathyroidism (PHPT). Ectopic parathyroid adenomas arise within the parathyroid glands located at the four poles of the thyroid [2]. Ectopic parathyroid adenomas result from aberrant migration of the gland during the early stages of development and can be identified in up to 16% of cases of PHPT [3]. They are commonly found in the mediastinum, within the thyroid, and along the path of the vagus or recurrent laryngeal nerves [4]. 45% of ectopic parathyroid adenomas are found in the paraesophageal region, 25% in the cervical thymus, 20% in the cervical mediastinum, 5% in the anterior portion of the mediastinum, and 5% at the level of the thymus [5]. A 64-year-old man with a past medical history of over 20-year history of recurrent nephrolithiasis, type II diabetes mellitus, dyslipidemia, hypertension, and pancreatic cancer presented to our outpatient endocrine clinic for evaluation of hyperparathyroidism. Further investigation of his history revealed that he had struggled with several bouts of urinary calculi throughout his life. These episodes required multiple surgical interventions to treat, including left nephrectomy and ureteral stenting. He had been evaluated for high serum calcium in the past and was diagnosed with PHPT by his urologist, who referred him to our clinic. Also complicating his health was a recent diagnosis of prostate cancer for which, he was undergoing radiation treatment. He had a family history of thyroid disorder in his mother but no family history of parathyroid disorders. Physical examination was unremarkable. Laboratory investigations revealed high serum calcium and high serum parathyroid hormone. Parathyroid scintigraphy with 99mTc-sestamibi revealed a subtle persistent focal region of increased uptake in the left axilla with no other areas of increased uptake, raising the suspicion for parathyroid adenoma in the left axilla. As discussed earlier, ectopic parathyroid adenomas result from aberrant migration of parathyroid tissue during embryological development. Additionally, ectopic parathyroid adenomas are a cause of failed surgery for hyperparathyroidism as well as persistent and recurrent hyperparathyroidism [3, 7-9]. Ectopic parathyroid tissue has a prevalence of 2-43% in anatomic series and has been detected in up to 16% of patients undergoing evaluation for hyperparathyroidism [3, 7, 10]. Ectopic parathyroid adenomas arising within the axilla may present with hypercalcemia and associated skeletal and renal involvement [11, 12]. The case that has been reported had a presentation of PHPT with recurrent nephrolithiasis. As mentioned earlier, 45% of ectopic parathyroid lesions are found in the paraesophageal region with 38% arising within the thymus [7, 10]. However, in this case, the patient presented with a possible ectopic parathyroid adenoma localized to the left axilla and no other areas of increased uptake on tc99m-sestamibi parathyroid scintigraphy.

Mandibular brown tumor revealing an ectopic parathyroid adenoma

The case report presents a 47-year-old female patient. She was suffering a painful clinical mandibular lesion. The histological diagnosis returned in favor of a brown tumor (osteitis fibrosa cystica). The patient did not present any signs of hypercalcemia. The biology report shows an hypercalcemia and an elevated parathyroid hormone (PTH) levels. The Sestamibi (methoxyisobutylisonitrile) scintigraphy returned in favor of an ectopic pathological parathyroid tissue in the upper mediastinal zone. The excision of this tissue revealed a parathyroid adenoma, which normalized the metabolic state and regressed the mandibular lesion. This case study highlights the importance of the dosage of parathyroid hormones and the calcemia in identifying the origin of osteitis fibrosa cystica.

PSUN76 Massive Four-Gland Parathyroid Hyperplasia: The Case of the Missing Glands

Abstract Introduction Parathyroid adenoma (PA) and parathyroid hyperplasia (PH) are common causes of primary hyperparathyroidism (PHPT) for which the only definitive treatment is surgical removal. Surgery is often preceded by imaging for localization, including by ultrasound (US), Sestamibi scan (MIBI), positron emission tomography/computer tomography (PET/CT), and four-dimensional computed tomography (4D-CT). While it is common for parathyroid pathology to not be visualized on imaging, non-visualization is more typical of adenomas and hyperplasia of smaller size. Clinical Case A 65-year-old male without history of kidney dysfunction or family history of parathyroid disease was referred to surgery for parathyroidectomy to manage longstanding PHPT. Serology showed a parathyroid hormone (PTH) level of 581 pg/mL (reference range: 12-65 pg/mL) and calcium of 11.8 mg/dL (reference range: 8.6-10.5 mg/dL). Preoperative parathyroid localization US revealed a large well-defined 1.5 cm PA. The patient underwent parathyroidectomy, which detected a large right inferior parathyroid gland, confirmed with pathology to be an atypical parathyroid adenoma weighing 1800 mg. Postoperative PTH level was 550 pg/mL and calcium was 12.6 mg/dL. MIBI did not display any definite parathyroid adenoma or ectopic parathyroid tissue. Further evaluation with PET/CT did not demonstrate any evidence of metabolically active residual or ectopic parathyroid adenoma or metastatic disease, and repeat US showed did not reveal evidence of any abnormal parathyroid tissue. Ultimately, 4D-CT detected a multiglandular parathyroid with a 1.8×1.4×3.0 cm right superior adenoma weighing approximately 3931 mg, 1.2×0.8×2.1cm left superior adenoma weighing approximately 1048 mg, and a 0.3×0.4×0.4cm left superior adenoma weighing approximately 25 mg. The patient underwent re-exploration parathyroidectomy with removal of the right superior adenoma weighing 3105 mg and left superior adenoma weighing 1100 mg. The remaining left inferior gland was biopsied and the majority of it was implanted into the arm. Repeat serology one week post-operatively showed improvement of PTH level to 5 pg/mL and of calcium to 8.9 mg/dL and serology one year post-operatively showed a PTH level of 82 pg/mL and a calcium of 9.4 mg/dL. Conclusion We present a patient with massive four-gland PH who initially presented with findings more typical of PA, but ultimately had additional hyperplasic glands that were identified after removal of the adenomatous gland. These glands were unusually large to be seen in PH and yet still be undetected on multiple imaging modalities; no previously reported non-ectopic hyperplastic glands of this size have been documented that were not detected on US or MIBI. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

A rare case of asymptomatic hyperplastic ectopic parathyroid tissue within the thymus: what are the clinical implications?

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Large Mediastinal Ectopic Parathyroid Adenoma Causing Malignant Hypocalcaemia in a Young Female: A Case Report and Review of Literature

Ectopic parathyroid tissue can pose difficulties in diagnosis and management of patients with hyperparathyroidism. Due to the embryological origins of the inferior parathyroid glands from the 3^rd pharyngeal arch where they develop with the thymus; they can have variable anatomical locations, including the anterior mediastinum. While the incidence of ectopic parathyroid glands varies in the literature mediastinal parathyroid tissue is extremely rare.

Pseudodiverticulum of the Cervical Esophagus With Remnant of Branchial Tissues in a Newborn: A Case Report

Congenital pseudodiverticula of the esophagus are very rare. This case report describes the presentation, management and histopathology of a peudodiverticulum of the cervical esophagus in a neonate. The infant presented with respiratory distress and a right neck mass that required surgical excision. Pathology revealed a pseudodiverticulum that contained ectopic thymic, thyroid, and parathyroid tissue within the wall of the lesion. The presence of ectopic tissues of branchial origin and an aberrant right subclavian artery suggest an error in branchial development and neural crest cell migration.

Ectopic pure mediastinal parathyroid adenoma: A case report.

Introduction and importanceThe ectopic parathyroid adenoma is an important cause of refractory and recurrent hyperparathyroidism. The mediastinal location of ectopic parathyroid tissue is reported in up to 20% of cases of ectopic parathyroid adenomas. In around 2% of cases where cervical approach is unfeasible, the mediastinal route imposes a surgical challenge.Case presentationWe describe a case of a twenty-five-year-old male patient with manifestations of hyperparathyroidism. Computed tomography of the chest showed an anterior mediastinal mass. Nuclear scintigraphy detected a functioning parathyroid tissue in the mediastinum. The mass was excised en block with the surrounding adipose tissue using a three-port video-assisted thoracoscopic surgery. The patient showed a full symptomatic and laboratory recovery.Clinical discussionMediastinal parathyroid glands comprise a unique surgical entity with diagnostic and management difficulties.ConclusionMediastinal parathyroid gland is a rare yet important cause of refractory hypercalcemia. The current localization tools improve the thoracoscopic management of MPAs. VATS can provide access and exposure to ectopic parathyroid adenoma with low morbidity.

Persistent Calciphylaxis and Secondary Hyperparathyroidism in End Stage Renal Disease Patient Due to Ectopic Mediastinal Parathyroid Adenoma- A Case Report

Intruducion: Secondary hyperparathyroidism (SHPT) is prevalent in patients with end-stage renal disease (ESRD) with reported prevalence of 90%. SHPT treatment is usually medical. Although 5% ends up with parathyroidectomy. Indications of parathyroidectomy in ESRD patients include persistent elevation of PTH more than 800, Calcyphylaxis, Osteitis Fibrosa Cystica, and persistent anemia. Among these patients who require surgery, 5–20% present with persistent or recurrent disease and require further re-exploration and excision of parathyroid tissue. We present a case of persistent Calciphylaxis and SHPT in ESRD patient despite Parathyroidectomy which prompted diagnosing an ectopic mediastinal parathyroid adenoma. Case Presentation: 49 year-old male with ESRD for 15 years complicated with SHPT, presented due to worsening Caciphylaxis of bilateral lower extremities despite Cinacalcet, IV sodium thiosulfate, and Phosphate binder. Serum Calcium level was 9.0 mg/dl with corrected levels of 10.2 mg/dl, Phosphorus level of 9.3 with Intact PTH level 1,369 pg/ml. Ultrasound of parathyroid glands was normal. Due to failure of medical treatment, He underwent Total parathyridectomy and left arm parathyroid autograft. Intraoperative PTH level went down to 300 (less than 50%). Calciphylaxis never improved. 5 months later, Parathyroid hormone was elevated 1338 pg/ml, Calcium level 6.9 mg/dl and Phosphorus level 10.0 mg/dl. 99mTc-sestamibi parathyroid scan didn’t show any activity in thyroid gland area and no increased uptake at the autograft area. Although it showed a small focus of persistent activity in substernal area suggestive of ectopic parathyroid tissue. Patient was referred for removal of ectopic adenoma. Discussion: Persistent SHPT is identified as the persistence or recurrence of symptoms, lab abnormalities and radiologic findings within 6 months after parathyroidectomy. Pathophysiology of recurrence is not well studied but one theory suggests that in SHPT, altered Calcium-phosphate hemostasis leads to hyperplasia of parathyroid tissue including ectopic and supernumerary tissue. This aforementioned altered hemostasis continues even after parathyroidectomy and cause hyperplasia and hyperfunction of the residual parathyroid tissue left accidentally by seeding within surgical site or implanted autograft or It can present with ectopic adenoma, even if they were undetected prior to or in the first intervention. Ectopic parathyroid tissue is an uncommon etiology of persistent or recurrent secondary hyperparathyroidism, it is reported in many cases where it was missed at initial workup. Prevalence reported up to 14% in patients with persistent SHPT. It is warranted further investigations to look for ectopic parathyroid tissue in patients with ESRD who present with recurrent or persistent secondary hyperparathyroidism after total parathyroidectomy with reimplantation.

In Search of a Missing Adenoma

Background: The most common cause of primary hyperparathyroidism (PHPT) is overproduction of PTH by a parathyroid gland adenoma. While definitive therapy is parathyroidectomy, 4% of patients develop persistent PHPT - a sustained hypercalcemic state that is detected within six months of parathyroidectomy. A missed parathyroid adenoma is the most common cause of persistent PHPT, and accurately locating these glands presents a diagnostic challenge. We describe a rare case of persistent PHPT due to a missed mediastinal parathyroid adenoma.Case: A 54-year-old woman with a history of PHPT presented with abdominal pain, nausea, and decreased oral intake. She underwent parathyroidectomy six months ago with reimplantation of one parathyroid gland into the right sternocleidomastoid muscle (SCM). She was now hypercalcemic to 13.9 mg/dL (8.5–10.5) with intact PTH 1273 pg/mL (15.0–65.0), vitamin D 25-OH 31.4 ng/mL (>30.0), and normal PTHrP. She was not taking calcium, and other causes of hyperparathyroidism were excluded. Sestamibi scintigraphy localized only to the right SCM, and the initial impression was recurrent HPT due to the previously implanted gland. Follow-up CT neck with and without contrast failed to localize any regrowth in the SCM, but did reveal a 1.4 cm mediastinal soft tissue mass, suspicious for an ectopic parathyroid adenoma. She subsequently underwent video-assisted thoracoscopic excision, and pathology was consistent with ectopic hypercellular parathyroid tissue. Post-operatively, her PTH down-trended and calcium normalized.Conclusion: This case describes a small yet biochemically aggressive mediastinal adenoma causing persistent PHPT. While sestamibi scans have ~90% sensitivity for localization of ectopic adenomas, they can fail to identify a small culprit lesion in 12% of patients, whereas CT imaging with and without contrast has increased sensitivity for adenomas <2 cm. Thus, diagnosing persistent PHPT requires sestamibi scan in combination with other imaging modalities for accurate diagnosis of missed adenomas.

Video-assisted thoracoscopic surgery for primary hyperparathyroidism with ectopic parathyroid adenoma in thymus

Introduction. Primary hyperparathyroidism is rare pathology in children (2?5:100,000). In more than 85% of patients, a single adenoma is present, and its extirpation is usually the only treatment a patient requires. In approximately 15?80% of cases, ectopic mediastinal parathyroid tissue can be found inside the thymus. Case outline. Our patient was a 13-year-old boy, who presented with multiple bone fractures in the previous period of time, and fatigue. Parathyroid hormone levels preoperatively were extremely high (1320 pg/ml ? more than 19 times higher than normal). Serum calcium was also elevated (total 3.55 mmol/l; ionized 1.41 mmol/l). He was examined and diagnosed as primary hyperparathyroidism by a pediatric endocrinologist. Imaging procedures for the preoperative localization of parathyroid adenomas were done (99mTc sestamibi scintigraphy and magnetic resonance imaging suggested ectopic mediastinal parathyroid adenoma). The patient underwent video-assisted thoracoscopic surgery procedure. After exploration of the mediastinum and chest, no ectopic parathyroid tissue was found, so total thoracoscopic thymectomy was performed. Final pathological section confirmed parathyroid adenoma inside the thymus. Conclusion. We believe that if no parathyroid tissue is found during surgical exploration of mediastinum, in a child with preoperatively detected parathyroid adenoma in anterior mediastinum, recommendation is to think about possible intrathymic localization and consider removing the thymus. Greater sample size is necessary for higher reliability of this statement.

Mediastinal Paratiroid Adenomlarının Tedavisinde SPECT/BT Rehberliğinde Uygulanan Minimal İnvazif Girişimler

Locating and removing ectopic parathyroid tissue may result in more than 20% failure. Seven cases which were detected by single photon emission computed tomography/computed tomography (SPECT/CT) imaging with Tc-99m sestamibi and treated with minimally invasive surgical methods were presented. The cases that underwent SPECT/CT due to high parathormone (PTH) level after total/subtotal parathyroidectomy operation, and detected to have mediastinal ectopic parathyroid were included. The success of the surgery was assessed with preoperative and postoperative PTH levels. Video-assisted thoracic surgery (VATS) was performed on five of the cases and video-assisted mediastinoscopy (VAM) was performed on remaining two. The mean age was 52.4±19.0. There were six women and one man. Mediastinal adenomas ranging from 1.5 to 6 cm in size, were successfully treated after single attempt. If the mediastinal ectopic parathyroid adenomas are fully localized before surgery, it can be treated with minimally invasive surgical methods.

MON-LB058 Mediastinal Parathyroid Adenoma Presenting as a Neuroendocrine Tumor

Introduction: Tertiary hyperparathyroidism caused by renal failure can lead to ectopic parathyroid tissue hyperplasia creating a diagnostic challenge. Here we describe a case of mediastinal parathyroid hyperplasia presenting as a neuroendocrine tumor. Case Presentation: A 40-year-old male presented for endocrine workup of a possible mediastinal paraganglioma. At age 22 he was diagnosed with resistant hypertension followed by rapidly progressive renal failure. Hemodialysis was initiated following a failed kidney transplant at age 30. He was treated by nephrology for secondary hyperparathyroidism with calcitriol and cinacalcet and serum calcium was within the normal range. Parathyroid hormone (PTH) was 598 pg/mL (12-65 pg/mL). The patient developed shortness of breath and a right pleural effusion while awaiting a second transplant and a CT of the chest was completed. This revealed a 3.1x4.0x5.0 cm heterogenous mediastinal mass within the superior thorax, medial to the proximal thoracic esophagus, and posterior to the trachea at the level of T2. It did not communicate with the thyroid gland. An FNA of the mass showed cohesive groups of atypical cells with small uniform nuclei and a moderate amount of chromatin arranged in nests and acini. No mitotic figures were identified. Cells were positive for chromogranin and focally for CK7, and negative for CK20, synaptophysin, and TTF-1. Cytology was interpreted as a well differentiated neuroendocrine tumor/typical carcinoid. A Galium-68 DOTATATE scan revealed moderate tracer uptake in the mass only. His endocrine workup was notable only for a mildly elevated chromogranin A with normal serum catecholamines, calcitonin, and serotonin, as well as normal adrenal cortical function. The patient underwent thoracotomy with mediastinal mass resection. He developed severe postoperative hypocalcemia treated with calcium infusion and increased calcitriol doses. Pathology revealed a low-grade neuroendocrine tumor consistent with parathyroid hyperplasia with at least one lymph node positive for involvement. The tumor showed positive staining for PTH, chromogranin, and synaptophysin with Ki67 <1%. Conclusion: This case demonstrates a rare occurrence of mediastinal parathyroid hyperplasia related to tertiary hyperparathyroidism of renal failure. Early calcitriol replacement and PTH level monitoring represents the mainstay of prevention of tertiary hyperparathyroidism. Severe post-op hypocalcemia is a hallmark of disease and more extensive immunostaining of mediastinal masses should be applied in cases suggestive of parathyroid etiology, especially in patients with long-standing renal failure. Despite a low Ki67, lymph node involvement suggests the possibility of parathyroid carcinoma. Follow-up Gallium-68 DOTATATE scan and parathyroid scan are imperative to evaluate for recurrence or residual disease. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. s presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.

SUN-494 Multiple Ectopic Parathyroid Foci: An Unexpected Finding Leading to Primary Hyperparathyroidism

Background: A patient with severe hypercalcemia and extremely elevated PTH levels found to have multiple foci of ectopic parathyroid tissue. Clinical Case: A 60-year-old female with a history of hypothyroidism and hypertension was transferred from another facility for evaluation for a parathyroidectomy. Vital signs were within normal limits. Initial evaluation revealed a corrected calcium of 8.2 mg/d, albumin level of 2.4 g/dL (n 3.2 - 4.6 g/dL). Creatinine was within normal limits. PTH level of 908 pg/dL (n 9.0 - 77.0 pg/dL), 25-vitamin D level of 15 ng/mL. The patient was recently admitted to another facility for septic shock secondary to UTI. She was found to have bilateral renal stones, for which she underwent ureteral stent placement. Further workup revealed severe hypercalcemia of 20.0 mg/dL and a PTH level >2,500 pg/dL. She was treated with IV fluids, bisphosphonates, calcitonin and cacimimetics. She was discharged with the plan for an outpatient parathyroidectomy. Prior to the parathyroidectomy, the patient was readmitted for acute respiratory failure. A parathyroid NM scan was performed and revealed no persistent uptake to suggest a parathyroid adenoma. She was subsequently transferred and admitted to our facility.During the admission, ENT and endocrinology were consulted. A NM scan was repeated, which showed a questionable right lower pole thyroid focus concerning for a parathyroid adenoma. 4D CT scan had concordant findings. Due to the exceedingly elevated PTH level, there was concern for parathyroid carcinoma. Patient underwent right thyroid lobectomy, parathyroidectomy with four-gland exploration, right central neck dissection, and reimplantation of ½ left super parathyroid to the left sternocleidomastoid. After the surgery, calcium and vitamin D supplementation were initiated. Her calcium levels remained stable throughout the hospital course. Operative parathyroid pathology revealed normal parathyroid glands with no malignancy, in addition to 12 foci of ectopic parathyroid glands. Conclusion: Treatment of primary hyperparathyroidism with parathyroidectomy is efficacious in 80-97% of initial explorations. The ability to locate ectopic glands are linked to the failure or success rates. Although ectopic parathyroid glands are common (15%), multiple ectopic glands, as in this case, are rarely reported.

Abstract #178 Case of Recurrent Hyperparathyroidism Secondary to Ectopic Parathyroid Tissue Requiring Multiple Surgeries

Abstract #178 Case of Recurrent Hyperparathyroidism Secondary to Ectopic Parathyroid Tissue Requiring Multiple Surgeries