CASR and adenoma: IHC demonstrated robust Thymosin expression in thymus, with heterogeneous/apical distribution in parathyroid tissue; CaSR showed strong membranous and cytoplasmic expression in parathyroid, but weak diffuse signal in thymus; PTH1R exhibited low-to-moderate expression in thymus and moderate heterogeneous expression in parathyroid, with apical accentuation in adenomas.