Session: MON 199-237-Disorders of Parathyroid Hormone & Calcium Homeostasis
Poster Board MON-209
Parathyroid carcinoma is an uncommon endocrine malignancy. A double primary and/or an intrathyroidal parathyroid carcinoma are yet more exceedingly rare.
We report a case of hypercalcemia secondary to primary hyperparathyroidism from double parathyroid carcinoma in a 54-year-old Filipino lady. She has a history of benign colloid nodular goiter status post subtotal thyroidectomy 30 years ago and was on thyroid hormone replacement therapy since then. She was diagnosed 3 years ago with staghorn nephrolithiases, with normal calcium levels. This year, she was noted to have hypercalcemia. She had elevated ionized calcium (1.39 mmol/l) and intact PTH (276 pg/ml). Thyroid ultrasound revealed left lobe solid nodules and right lobe complex nodule. Parathyroid 99mTc-(sestaMIBI) scintigraphy showed an avid focus in the left thyroid bed likely due to hyperactive parathyroid adenoma, malignancy cannot be ruled out, and a scintigraphic evidence of complex thyroid nodule in the right lobe. Bone (DEXA) densitometry revealed osteopenia. Surgery was performed using quick intraoperative intact PTH assay (QPTH). The intact PTH (54 pg/ml) and ionized calcium (1.14 mmol/l) levels fell to normal range after removal of both tumors. Histopathological examination revealed a multinodular colloid adenomatous goiter on the right thyroid lobe, a parathyroid carcinoma within the left thyroid lobe with a tumor size of 2 cm in its widest diameter, and a left superior parathyroid carcinoma measuring 1.1 and 2.3 cm in its widest diameter with lymphovascular invasion and tumor infiltration of surgical margins. There was no other evidence of distant metastasis or part of MEN Syndrome 1. To the best of our knowledge, this is only the sixth case report of double parathyroid carcinoma confirmed histologically.
Preoperative and intraoperative diagnosis of parathyroid carcinoma is challenging, especially if localized within the thyroid gland [1-2]. Current techniques such as thyroid ultrasound and sestaMIBI scanning may fail to differentiate an adenoma versus a malignancy . Fine needle aspiration [1,4] and intraoperative biopsies [1,5] are also of limited value in diagnosing parathyroid carcinoma, and in fact should be avoided to prevent needle track seeding[6,7]. Primary en bloc resection of the tumor, avoiding capsule rupture and spillage of the tumor cells, is the procedure of choice [6,7]. Other treatment modalities such as chemotherapy and radiotherapy have been largely ineffective in the treatment of parathyroid carcinoma [6,8]. Our case indicates that QPTH is the useful tool for detecting double parathyroid tumors even if one is located in the thyroid gland [1,5,9].
Nothing to Disclose: KAA, COR, JD, MLV
*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm
See more of: Abstracts - Orals, Featured Poster Presentations, and Posters