|Year : 2012 | Volume
| Issue : 2 | Page : 68-70
Ectopic parathyroid adenoma
Caren Dsouza1, KR Bhagavan1, Gopalakrishnan2, K Rakesh1
1 Department of General Surgery, KS Hegde Medical College, Mangalore, India
2 Department of Cardiothoracic Surgery, KS Hegde Medical College, Mangalore, India
|Date of Web Publication||12-May-2012|
Department of General Surgery, KS Hegde Medical College, Mangalore
Adenoma is the commonest cause of primary hyperparathyroidism; 10% of these adenomas can be ectopic, leading to one of the major causes for persistent and recurrent hyperparathyroidism. Proper preoperative evaluation is important in order to localize the position of the glands. We report a case of a 21-year-old male who presented with features of primary hyperparathyroidism. On evaluation with metaiodobenzylguanidine scan, he was found to have a parathyroid adenoma in the mediastinum, anterior to the arch of the aorta. The adenoma was excised via a sternotomy incision.
Keywords: Ectopic parathyroid, metaiodobenzylguanidine scan, parathyroid adenoma
|How to cite this article:|
Dsouza C, Bhagavan K R, Gopalakrishnan, Rakesh K. Ectopic parathyroid adenoma. Thyroid Res Pract 2012;9:68-70
| Introduction|| |
Primary hyperparathyroidism is the third most common endocrine disorder in adults. About 85% of the primary hyperparathyroidism is due to adenoma.  In 10% of the cases, these adenomas can be in ectopic positions. These ectopic adenomas are often small and difficult to localize due to which they are the major cause of persistent hyperparathyroidism. ,, The ineffectiveness of surgical exploration without preoperative radiological scans is known. Use of Tc 99 MIBI scans with CT scan is sufficient in most cases to localize ectopic adenomas. We have discussed one such case of primary hyperparathyroidism secondary to an ectopic adenoma.
| Case Report|| |
A 21-year-old male presented with complaints of pain in the epigastrium and both loins for a period of 1 year. He also gave history of loose stools and steatorrhea during this period. He had been admitted for these complaints elsewhere and was diagnosed to have pancreatitis and bilateral renal calculi. Abdominal examination showed mild tenderness in the epigastric region. Other systemic examination was normal. His serum amylase was 290 mg/dL and serum calcium was 11.3 mg/dL. Ultrasonography of the abdomen revealed calculus pancreatitis with bilateral renal parenchymal disease with multiple renal calculi. Parathyroid hormone level was 249.3 pg/mL. Ultrasonography of the neck did not reveal any enlarged parathyroids. CT scan of neck and thorax was done, which showed intensely enhancing small triangular soft tissue density in the anterior mediastinum, anterior to ascending aorta, measuring 15 mm × 14 mm. A 99mTc MIBI Scan was done, which confirmed the presence of an ectopic parathyroid gland in the mediastinum [Figure 1].
Via a midline sternotomy, the thymus gland along with the perithymic fat tissue and a suspicious nodular tissue was removed [Figure 2]. The histopathological examination showed the presence of a well-circumscribed nodule comprising of highly cellular monomorphic tumor cells with round nuclei, abundant granular eosinophilic cytoplasm - chief cells, arranged in acini [Figure 3]. Postoperatively, there have been no complaints of abdominal pain. Regular follow-up calcium values have been within normal limits.
|Figure 3: Histopathology: Highly cellular monomorphic tumor cells with round nuclei, abundant granular eosinophilic cytoplasm - chief cells, arranged in acini|
Click here to view
| Discussion|| |
During embryogenesis, the four parathyroids descend to the neck .The superior parathyroids arise from the fourth branchial arch and are usually positioned behind the superior pole of the thyroid. The inferior parathyroids arise from the third branchial arch and descend along with the thymus into the neck, and their anatomy is usually variable. ,, Though they are usually found adjacent to the inferior pole of the thyroid, they could lie within the suprasternal fossa, thyrothymic ligament, thymus, or perithymic fat in case of an ectopic gland.  The inferior glands located below the thymus or in the mediastinum are seen in 20% of the patients, and only 2% of these can be excised via cervical incision. 
Primary hyperparathyroidism is the third most common endocrine disorder in adults.  Primary hyperparathyroidism results from inappropriate overproduction of parathyroid hormone from one or more parathyroid glands, and presents with hypercalcemia.  Of the classical symptoms, nephrolithiasis is the most common and occurs in 15-20% of newly diagnosed patients with hyperparathyroidism.  About 85% of the primary hyperparathyroidism is due to adenoma , but multi-gland disease can occur in 10-15% of cases and double adenomas in 4-5%.  Most of the parathyroid adenomas are small, weighing less than 1 g.  In 10% of the cases, these adenomas can be in ectopic positions. These ectopic parathyroids could be of major concern since they are responsible for majority of the persistent or recurrent hyperparathyroidism.
The success of surgery in primary hyperthyroidism is based on clear diagnosis and preoperative localization methods. The currently used diagnostic techniques, which are non-invasive, include Tc - 99m MIBI scanning, SPECT, ultrasonography, CT imaging, and MRI. ,,
MIBI scintigraphy is one of the most widely used investigations in preoperative localization of parathyroid adenomas including the ectopic glands.  MIBG localizes in both thyroid and parathyroid glands initially. On the delayed images, the MIBI washes off from the thyroid and the normal parathyroid glands, showing persistent radioactivity in the hyperfunctioning parathyroid glands. 
Adenomas as small as 0.3 g are detectable by these localization studies. 
The only curative treatment for primary hyperparathyroidism due to adenomas is surgical excision of the gland. 
Intraoperative gamma probe was first used in 1997 to help in the intraoperative localization of the ectopic adenomas and is now being used by many surgeons for localizing the glands, especially in mediastinal parathyroids, as it is visually difficult to detect small parathyroid adenomas in the mediastinal tissue and distinguish them from normal tissue. This method was not used by us due to unavailability, and hence we had to dissect the thymus and the perithymic fat tissue. Minimally invasive radio-guided parathyroidectomy using gamma probes is associated with a high success rate. ,
| References|| |
|1.||Vijayakumar V, Anderson ME. Detection of ectopic parathyroid adenoma by early Tc -99m Sestamibi imaging. Ann Nucl Med 2005;19:157-9. |
|2.||Uludag M, Isgor A, Yetkin G, Atay M , Kebudi A, Akgun I. Supernumerary ectopic parathyroid glands. Persistant hyperparathyroidism due to medistinal parathyroid adenoma localized by preoperative single photon emission computed tomography and intraoperative gamma probe application. Harmones (Athens) 2009;8:144-9. |
|3.||Ishibashi M, Uchida M, Nishida H, Hiromatsu Y, Kohno K, Okuda S, et al. Pre-surgical localization of ectopic parathyroid glands using three-dimensional CT imaging, 99Tcm sestamibi and 99Tcm tetrofosmin imaging. Br J Radiol 1999;72:296-300. |
|4.||Zhang F, Yang X, Jiang J. Hyperparathyroid crisis caused by ectopic parathyroid adenoma in a pediatric patient. Int J Pediatr Otorhinolaryngol Extra 2011;6:39-41. |
|5.||Feder JM, Sirrs S, Anderson D, Sharif J, Khan A. Primary hyperthyroidism: An overview. Int J Endocrinol 2011:8. |
|6.||Ghandur-Mnaymneh L, Kimura N. The parathyroid adenoma. A histopathologic definition with a study of 172 cases of primary hyperparathyroidism. Am J Pathol 1984;115:70-83. |
[Figure 1], [Figure 2], [Figure 3]