Malignant Biochemical Profile of a Rare Benign Lesion: A Case Report of a Patient with a Functioning Cystic Parathyroid Adenoma

Presentation Number: MON 303
Date of Presentation: April 3rd, 2017

Mary Angelynne Esquivel*1 and Ricardo Rafael Correa-Marquez2
1Alpert Medical School of Brown University/Rhode Island Hospital, East Providence, RI, 2Alpert Medical School at Brown University, East Providence, RI



Neck swelling and compressive symptoms are the usual presentation of cystic parathyroid adenomas. They are subdivided into functioning and nonfunctioning, depending on their ability to secrete parathyroid hormone (PTH) or not. The vast majority of these lesions are non-functioning, and present as nodular cervical masses. Functioning cystic parathyroid adenomas are rare (9%) and predominantly occur in males. These lesions cause primary hyperparathyroidism, and at times, can result in acute hypercalcemic crisis or hyperparathyrotoxicosis.

Clinical Case:

A 51 yo Caucasian female with obesity and no other medical history, presented from an outpatient clinic for further evaluation and management of asymptomatic hypercalcemia (serum calcium 13.2 [Nl: 8.5-10.5 mg/dL] and albumin 4.3 [Nl: 3.5-5.0 g/dL] noted on routine laboratory testing. Further workup showed findings consistent with primary hyperparathyroidism as follows: calcium 14.3 mg/dL, PTH 1348 (Nl: 14-72 pg/mL) and low phosphorus 1.2 (Nl: 2.4-4.8 mg/dL). Other labs revealed vitamin D 25 OH 15.4 (Nl: 30.00-100 ng/mL), alkaline phosphatase 204 (Nl: 34-104 IU/L), creatinine 0.64 (Nl: 0.44-1.03 mg/dL) and BUN 13 (Nl: 6-24 mg/dL). Neck ultrasound showed findings consistent with a cystic parathyroid adenoma with a small portion of solid component, located inferior and extrinsic to the right lower pole of the thyroid gland measuring 4.3x4.2x2.5cm. Continuous aggressive IV fluid hydration and a dose of IV zoledronic acid 4 mg were instituted, which ultimately resulted in gradual normalization of serum calcium to 10.1 mg/dL within 5 days. Right parathyroidectomy was subsequently performed with intra-operative PTH monitoring (initial PTH 3487 pg/mL, final PTH 247 pg/mL). Laboratory results on post-op day 1 were: calcium 9.1 mg/dL and PTH 28 pg/mL. Pathology showed a right inferior parathyroid adenoma with a large cystic component, measuring 3.5x2.6x1.5cm, weighing 12.5 grams. Postoperative course was unremarkable and without complications. Follow up labs 3 months post-op showed PTH 96 pg/mL, calcium 9.5 mg/dL, phosphorus 3.0 and vitamin D 25 OH 28 ng/mL. Optimization of calcium and vitamin D intake was recommended, with plan for follow-up laboratory testing.


Functioning parathyroid cystic adenomas are rare, benign, lesions, whose biochemical profile can resemble that of parathyroid carcinomas (ie severe hypercalcemia with significantly elevated parathyroid hormone levels). Surgical resection is recommended for asymptomatic patients if they meet the criteria outlined for asymptomatic primary hyperparathyroidism. The understanding of its diagnostic and therapeutic approach constitutes a valuable knowledge for all healthcare providers, especially those dealing with calcium disorders and neck lesions.


Nothing to Disclose: MAE, RRC