Skull Base Surgery Atlas (stanford.edu)

How is pituitary carcinoma diagnosed in 2023?

• Purely clinically. It is not a histological diagnosis. It is diagnosed based on the presence of distal recurrences in the brain (eg posterior fossa) or spine.

After prolactinoma resection the prolactin level decreases substantially but remains elevated 24 hours after surgery. What does this say about likely extent of resection? 

• There is likely some residual. The half life of prolactin is very short and you would expect to see the level normalize quickly postop if you got a GTR

Cushing Disease

Causes of hypercortisolism: 

1. Iatrogenic is the most common
2. Endogenous
   1. Central, i.e. from the pituitary, 70% of the time
   2. Peripheral, i.e. from the adrenal gland, 29% of the time
   3. Paraneoplastic, 1% of the time. This is associated with very high ACTH levels

Symptoms: 

1. Weight gain
2. Abdominal striae
3. Easy brusing
4. Buffalo hump
5. Moon facies
6. Hypertension
7. Hirsutism

Mimics of Cushing: 

• PCOS
• Alcoholism causes an elevated ACTH level and central adiposity

Diagnosis of Cushing disease: 

1. Low dose dexamethasone suppression test
2. 24-hour urinary cortisol
3. Late night salivary cortisol x2

Dexamethasone suppression testing: 

• Low dose is used to diagnose Cushing disease.
  • Dexamethasone level is used to verify that the patient did, in fact, take the dexamethasone
  • If the AM cortisol is low, this is appropriate suppression and is what is seen in a normal individual
  • If the AM cortisol is high, the patient has Cushing disease
• High dose is to distinguish central from peripheral causes
  • If the AM cortisol is low, the diagnosis is central Cushing
  • If the AM cortisol is high, the diagnosis is peripheral Cushing