A 48-year-old man has primary hyperparathyroidism with serum calcium of 15.2 mg/dL, intact PTH of 1400 pg/mL, a palpable hard left neck mass, and hoarseness of three months' duration. Sestamibi shows intense uptake in the left lower neck. The most likely diagnosis and appropriate initial operation are:

• A Parathyroid adenoma, focused minimally invasive parathyroidectomy
• B Medullary thyroid carcinoma, total thyroidectomy with central node dissection
• C Parathyroid hyperplasia, four-gland exploration with subtotal resection
• D Parathyroid carcinoma, en bloc excision of the mass with ipsilateral thyroid lobectomy without capsular breach ✓

Explanation

Marked hypercalcaemia above 14 mg/dL, PTH five to ten times the upper limit, a palpable hard gland, and hoarseness suggesting recurrent laryngeal nerve invasion form the classic constellation of parathyroid carcinoma. Treatment is en bloc resection of the tumour, ipsilateral thyroid lobe, and involved soft tissue, taking care never to breach the capsule because rupture seeds local recurrence. A benign adenoma rarely presents as a palpable hard fixed mass with nerve palsy, which eliminates option A.

Reference: Williams Textbook of Endocrinology, 14th ed.

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Written and medically reviewed by the StethoPrep medical team.