Cushing syndrome with moon facies and buffalo hump

A 38-year-old woman on oral prednisolone 20 mg daily for 3 years due to steroid-dependent asthma presents with weight gain, easy bruising, and proximal muscle weakness. Examination reveals moon facies, supraclavicular fat pads, and a prominent **dorsocervical fat pad forming a buffalo hump (marked C)**, along with truncal obesity and thin extremities. Fasting glucose is 176 mg/dL, blood pressure 162/98 mmHg, and 8 AM ACTH is suppressed at <5 pg/mL with low morning cortisol. DEXA scan shows osteoporosis (T-score -2.8). Which of the following best describes the pathophysiology underlying the development of the structure marked **C** in this patient?