PSAT212 Hyperparathyroidism Secondary to Ectopic Parathyroid Adenoma

BACKGROUND: In the majority of cases, primary hyperparathyroidism is caused by a parathyroid adenoma, most commonly located within the parathyroid glands. However, in some cases, the parathyroid adenoma can be located aberrantly. CLINICAL CASE: A 78 year old female was referred due to hypercalcemia (ionized calcium 1.63mmol/L). Patient has been known to have elevated calcium (both total and ionized) levels for 3 years and osteoporosis. Initial work up on presentation had been unremarkable hence no further investigation was done and treatment was given. Prior to consult, patient had symptoms of bone pains, particularly in her lower extremities. Kidney function was normal. Patient had never had kidney stones but x-ray demonstrated compression fracture of L2 vertebrae. Work up for hypercalcemia was done, revealing the following results: PTH 196.60 pg/mL, TSH 1.810 mIU/mL, FT4 16.46 pmol/L, FT3 3.55 pmol/L, 24 hour urine calcium 88.40 mg/24 hours, and 25 (OH) D 18.32 ng/dL. Neck ultrasound showed findings of normal-sized thyroid gland with mild parenchymal change, benign cystic nodules and no definite evidence of parathyroid nodule. Parathyroid subtraction imaging was done and demonstrated no scintigraphic evidence of parathyroid adenoma or hyperplasia. Patient was prescribed with calcimimetics (Cinacalcet). However, the patient experienced nausea and body pains and opted to discontinue the medication. Further investigation was performed. Radionucleotide parathyroid imaging using Technitium-99m sestamibi was done which revealed slightly increased tracer activity in the lower midline neck on SPECT imaging, an atypical scintigraphic finding of an aberrantly located parathyroid adenoma possibly in the tracheoesophageal or retroesophageal region. There was no definite scintigtaphic evidence of parathyroid adenoma or hyperplasia in the thyroidal beds or ectopic parathyroid in the mediastinum. A second parathyroid scan with SPECT-CT was performed in another institution and showed a 1.2×1.0 cm, sestamibi avid nodule inseparable from the esophagus and left posterior aspect, anterior to the T2 vertebra, consistent with a thoracic retro-esophageal hyperfunctioning parathyroid adenoma. Patient refused surgery at this point and was given medical management with hydration, Vitamin D correction and antiresorptive agent. CONCLUSION: Multiple imaging may be needed to reach an accurate diagnosis for persistent hypercalcemia and elevated parathyroid hormone levels with an absence of lesions in the neck. If the criteria for surgery are met, as with parathyroid adenomas within the parathyroid gland, surgical resection is also the gold standard of therapy for ectopic parathyroid adenomas. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.