Aberrant migration of parathyroid glands from their embryologic origin may result in undescended parathyroid glands. We present a case of an ectopic parathyroid adenoma at the level of the pyriform sinus. A 41-year-old female was evaluated for primary hyperparathyroidism. Following non-localizing ultrasound and planar sestamibi imaging, the patient underwent SPECT/CT and 4-D computed tomography demonstrating evidence of an ectopic parathyroid adenoma. The surgical approach was modified based on the location. Following extirpation, PTH fell from 80 to 16 pg/mL, and the 15-min post-excision level remained stable at 14pg/mL, indicating a biochemical cure. While rare, undescended parathyroid adenoma should be considered when preoperative imaging fails to identify a target adenoma or after unsuccessful surgery. The combined use of 99m Tc-MBI or 4D CT and other anatomical scans may improve diagnostic accuracy. Due to the potential need to perform a second incision to conduct a four-gland exploration, preoperative patient discussion regarding surgical risks may differ from that of a standard parathyroidectomy.
Keywords: ectopic parathyroid; parathyroid adenoma; parathyroidectomy; primary hyperparathyroidism; undescended parathyroid gland.
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