PSAT202 A Rare Case of Four-Gland Parathyroid Adenomas

BACKGROUND: Amongst patients diagnosed with primary hyperparathyroidism, 80% have been identified to have a single parathyroid gland involvement, with 10% involving two glands or more. CASE: A 71-year-old female with medical history of hypothyroidism, multinodular goiter, CKD stage 3a, recurrent nephrolithiasis and hyperparathyroidism presented for evaluation of hypercalcemia. She was diagnosed with hyperparathyroidism 9 years prior to presentation however she preferred medical management with cinacalcet. For the past 5 months, she had been experiencing worsening fatigue, constipation, body aches and appetite loss. Further blood analysis revealed PTH 1176 pg/mL (14-64 pg/mL), TSH 2.69 uU/mL (0.35-4.94 uU/mL), free T4 1.12 ng/dL (0.60-1.89 ng/dL), vitamin D, 25-Hydroxy 24 ng/mL (30-80 ng/mL), serum calcium 12.6 mg/dl (8.9-10.4 mg/dL), ionized calcium 1.65 mmol/L (1.14-1.33 mmol/L), phosphorus 1.9 mg/dl (2.4-4.8 mg/dl), magnesium 1.0 mg/dl (1.8-3.0 mg/dL). Thyroid ultrasound revealed a left isthmus heterogenous solid nodule measuring up to 2.0 cm and a separate nodule superior to the isthmus measuring up to 0.6 cm. Subsequent NM parathyroid scan was limited due to diffuse uptake of enlarged nodular thyroid. Although limited, imaging did reveal a small focus of uptake lateral to the right lower pole concerning for parathyroid adenoma. A CT 4D neck with and without contrast demonstrated a suspicious parathyroid adenoma posterior to the inferior aspect of the left thyroid measuring up to 1.7 cm, an additional 0.8 cm questionable node, and a 4 cm multicystic mass inferior to the right thyroid lobe concerning for exophytic thyroid nodule or multi cystic parathyroid adenoma. Due to persistence of symptoms and significantly elevated PTH levels concerning for carcinoma, decision was made to undergo a four-gland parathyroid exploration and a right hemithyroidectomy. A right superior parathyroid adenoma was identified; after resection, intraoperative PTH levels failed to improve which prompted further exploration. Left superior and inferior parathyroid adenomas were identified and resected. An ectopic nodule located in the right superior mediastinum with surrounding normal parathyroid tissue was identified and dissected, leaving parathyroid tissue behind. Post operatively, PTH levels appropriately decreased to 54 pg/ml. Pathology of identified parathyroid glands had hypercellular parathyroid tissue with fibrous capsule, consistent with adenomas. Interestingly, the pathology of the presumed ectopic nodule was consistent with atypical parathyroid adenoma. Immunostatins with parafibromin demonstrated nuclear immunoreactivity in the lesional cells, consistent with a benign neoplasm. Patient developed symptomatic hypocalcemia following surgery. She was gradually weaned off calcitriol and is currently normocalcemic. CONCLUSION: It is extremely rare to have adenoma of 4 parathyroid glands simultaneously in the absence of genetic conditions associated with hyperparathyroidism. Age of onset of hyperparathyroidism and absence of other endocrine abnormalities clinically was reassuring, however; further biochemical and genetic testing will be considered in this patient. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.