Acromegaly — Coarse Facies, Prognathism, Macroglossia

A 48-year-old man presents to the endocrinology clinic with progressive coarsening of facial features, increased shoe size by 2 sizes over 5 years, and a wedding ring that no longer fits. On examination, he demonstrates characteristic acromegalic facies with prominent supraorbital ridges, enlarged nose, thickened lips, and the feature marked **C** in the diagram. He also reports bifrontal headaches, excessive sweating, and recent-onset type 2 diabetes mellitus. MRI pituitary reveals a 1.4 cm macroadenoma with suprasellar extension. Which of the following best describes the skeletal pathology at the structure marked **C** and its clinical significance in acromegaly?