In parathyroid carcinoma, which is the most reliable intraoperative feature distinguishing it from a parathyroid adenoma?
- A Large gland weight >3.5 g with cystic change and calcification
- B Markedly elevated intraoperative PTH (>1000 pg/mL) that falls by >50% after removal
- C Firm grey-white gland with fibrous bands and dense adhesion to surrounding tissues ✓
- D Pale yellow colour with a visible central vascular stalk
Correct answer: C. Firm grey-white gland with fibrous bands and dense adhesion to surrounding tissues
Explanation
Parathyroid carcinoma is distinguished intraoperatively by its firm, grey-white fibrous texture with dense adherence to the thyroid lobe and surrounding structures, unlike the soft, tan-yellow adenoma. Histological criteria (thick fibrous capsule, vascular invasion, perineural invasion, mitotic figures in 2+ mitoses/HPF) are required for definitive diagnosis. The key surgical principle is en bloc resection including adherent thyroid and isthmus to achieve clear margins, as incomplete resection leads to high local recurrence.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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