Cushingoid Striae — Iatrogenic Steroid Excess

A 45-year-old woman on long-term prednisolone (40 mg daily for 18 months) for systemic lupus erythematosus presents with progressive weight gain, proximal muscle weakness, and easy bruising. On examination, the structure marked **A** in the diagram—wide purple striae (>1 cm) with deep violaceous color over the abdomen and thighs—is noted. Which of the following best explains the pathophysiology of these striae in Cushing syndrome?