Which markers constitute the IHC panel for primary parathyroid carcinoma?

• A. Inhibin and SF-1
• B. PTH and chromogranin
• C. SALL4 and LIN26
• D. Cyclin D1 and CD10

Answer: (B)

The key idea is identifying parathyroid origin through its hormone production and neuroendocrine characteristics. PTH staining shows the tumor is producing parathyroid hormone, which directly supports a parathyroid origin. Chromogranin A is a neuroendocrine marker that is commonly positive in parathyroid tissue, reinforcing the parathyroid nature of the tumor. The other marker pairs point to different tissues or tumor types—Inhibin and SF-1 for adrenal or gonadal lineage, SALL4 and LIN28 for germ cell tumors, and Cyclin D1 with CD10 for other lymphoid or non-parathyroid neoplasms—so they’re not as specific for parathyroid carcinoma. Therefore, combining PTH with chromogranin A provides the most appropriate IHC panel for primary parathyroid carcinoma.