Table 1

Overview of endogenous Cushing

AetiologyAssociated biochemical featuresAssociated radiological featuresAssociated pathological features
Pituitary ACTH (∼70%)ACTH >15 pg/mL
CRH+
HDD+
Pituitary MRI±
BIPSS+
Pituitary corticotroph adenoma and Crooke's hyaline change in the non-tumorous corticotrophs; secondary diffuse±nodular adrenal cortical hyperplasia
Ectopic ACTH (∼10%) or CRH (<1%)ACTH >15 pg/mL
CRH−
HDD−
Pituitary MRI−
BIPSS−
Primary neuroendocrine tumour; secondary diffuse adrenal cortical hyperplasia
Primary adrenal hypercortisolism (∼20%)ACTH <5 pg/mL
CRH−
Pituitary MRI−
Adrenal CT or MRI+
Adrenal cortical hyperplasia, adenoma and carcinoma
  • ACTH, plasma corticotropin concentration; BIPSS, bilateral inferior petrosal sinus sampling; CRH, corticotropin releasing hormone stimulation test; HDD, high-dose dexamethasone suppression test.