23rd May 2025

A 36-year-old male has been experiencing low mood, weight gain, rounding of his face over the last few years.

A 36-year-old male has been experiencing low mood, weight gain, rounding of his face over the last few years. His GP recently diagnosed tinea versicolor infection. Bloods revealed he is pre-diabetic. The patient was referred to the hospital for further investigations. Following administration of dexamethasone, his plasma cortisol levels were 2 micrograms/dL the next morning. After this, morning plasma ACTH levels were 8 picomol/L. 

What is the most likely cause of his symptoms?

Select the SINGLE most appropriate option from the list below. Select ONE option only.