An Intraoperative Diagnosis of Intrathyroid Parathyroid Adenoma in a 34-year-old Hispanic Female: A Case Report

Background: Up to 85% of primary hyperparathyroidism is caused by a single parathyroid adenoma, which most commonly occurs in the external aspect of the inferior pole of the thyroid. In rare cases, they are found within the thyroid gland. Even with recent advancements in ultrasound (US), Tc-99m sestamibi scintigraphy, and computed tomography (CT) scan, preoperative localization of intrathyroid parathyroid adenomas (IPA) may be difficult. Surgeons may occasionally be required to make an intraoperative diagnosis and perform an unplanned hemithyroidectomy. Case description: A 34yo Hispanic female was referred due to complaints of multiple episodes of nephrolithiasis, recent onset of arthritis in her hands and wrists, bilateral hearing loss, and fatigue. Her labs showed 130 pg/mL PTH, 11.0 mg/dL Ca, and 6.1 mg/dL ionized Ca. Further workup with US imaging and sestamibi scintigraphy revealed a single left parathyroid adenoma. The patient subsequently underwent a selective parathyroidectomy. Intraoperatively, the posterior aspect of the gland was looked over carefully to locate the parathyroid adenoma as previously seen on US. However, no adenoma was visualized on the superior or inferior poles. A decision was made to resect the left thyroid lobe. The resected specimen was then sent to pathology for an intraoperative frozen section examination, which confirmed the presence of the IPA. Conclusion: A definitive preoperative diagnosis of IPA may be limited with current imaging modalities. Our case report suggests that an IPA can be diagnosed intraoperatively using frozen section following a careful exploration.