A apparent interval contralateral localization of a retrovisceral parathyroid adenoma: A diagnostic pitfall on sequential imaging

Parathyroid adenoma is the most common cause of primary hyperparathyroidism, and accurate preoperative localization is essential for successful minimally invasive parathyroid surgery. However, discordant imaging findings may lead to failed surgical exploration and significant diagnostic uncertainty. We report a rare case of a 54-year-old woman with biochemically confirmed primary hyperparathyroidism in whom initial ultrasound and contrast-enhanced computed tomography demonstrated a hypervascular soft tissue lesion posterior to the left thyroid lobe, suspicious for parathyroid adenoma. Based on these findings, minimally invasive left cervical exploration was performed, but failed to identify the lesion. Repeat multimodality imaging performed two weeks later demonstrated a hyperenhancing nodule posterior to the right thyroid lobe associated with postoperative inflammatory changes in the retroesophageal space. Careful correlation of sequential imaging studies suggested that the lesion was located within a loose retroesophageal connective tissue plane, allowing apparent interval contralateral displacement rather than true ectopic localization. Subsequent reoperation confirmed a right-sided parathyroid adenoma. This case highlights an unusual imaging pitfall in parathyroid localization and emphasizes the importance of repeat multimodality imaging following unsuccessful minimally invasive exploration.