During reoperation for persistent primary hyperparathyroidism, an ectopic parathyroid adenoma is most frequently found in which location?

• A Retro-oesophageal space behind the pharynx
• B Carotid sheath at the skull base
• C Thymus or anterior superior mediastinum ✓
• D Intrathyroidal, requiring lobectomy

Explanation

The inferior parathyroids arise from the third pharyngeal pouch together with the thymus and descend with it, so they have a long, variable migration path. Missed inferior glands are therefore most often located within the thymus or anterior mediastinum, retrievable through a cervical thymectomy approach. Superior glands arise from the fourth pouch and migrate only a short distance, making them far more constant in position near the cricothyroid junction or tracheo-oesophageal groove, which makes option A less likely overall.

Reference: Sabiston Textbook of Surgery, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.