What are the management options for pituitary adenoma?

Management of Pituitary Adenomas

Transsphenoidal surgery is the first-line treatment for most pituitary adenomas, except for prolactinomas which should be initially treated with dopamine agonists. 1

Diagnostic Approach

Initial Evaluation

• MRI Imaging: Pre-contrast (T1 and T2) and post-contrast-enhanced (T1) thin-sliced pituitary MRI, including post-contrast volumetric sequences for increased sensitivity 1
• Hormonal Assessment: Evaluate for gonadal, thyroid, and adrenal function as well as prolactin and growth hormone secretion 2
• Visual Field Testing: For macroadenomas (≥10mm) that may compress the optic chiasm 1
• Genetic Testing: Offer to all patients with pituitary adenomas, especially important for somatotroph and lactotroph tumors (GH and prolactin-secreting) 1

Treatment Algorithm by Adenoma Type

1. Prolactinomas (32-66% of adenomas)

• First-line: Medical therapy with dopamine agonists (bromocriptine or cabergoline) 3, 4
  • Effective for tumor shrinkage even with visual field defects
  • Often results in rapid improvement (within days) of visual disturbances
• Second-line: Transsphenoidal surgery if resistant to medical therapy 2

2. Growth Hormone-Secreting Adenomas (8-16% of adenomas)

• First-line: Transsphenoidal surgery 1
• Pre-operative considerations:
  • Consider somatostatin analogues and/or GH receptor antagonists to control symptoms and reduce height velocity, especially if surgery is delayed 1
• Second-line/Adjunctive:
  • Somatostatin analogues for residual disease or when surgery is contraindicated 5
  • Pegvisomant (GH receptor antagonist) for resistance to somatostatin analogues 2
  • Radiotherapy for tumors that are symptomatic, growing, resistant to medical therapy, and surgically inaccessible 1

3. ACTH-Secreting Adenomas (2-6% of adenomas)

• First-line: Transsphenoidal surgery 2, 5
• Second-line:
  • Radiotherapy for subtotally resected tumors
  • Medical therapy with adrenal steroidogenesis inhibitors (mitotane, ketoconazole) while awaiting radiotherapy effects 2

4. TSH-Secreting Adenomas (1% of adenomas)

• First-line: Transsphenoidal surgery 5
• Second-line: Somatostatin analogues if not surgically cured 5
• Follow-up: Regular thyroid function tests and MRI surveillance 1

5. Non-functioning Adenomas (15-54% of adenomas)

• First-line for symptomatic macroadenomas: Transsphenoidal surgery 2, 5
• Incidental microadenomas: Observation with follow-up imaging 2
• Post-operative residual disease: Consider radiotherapy 1
• Surveillance: Gradually decreasing MRI frequency if stable 1

Surgical Approach

• Preferred technique: Transsphenoidal surgery, even in patients with incompletely pneumatized sphenoid sinuses 1
• Consider endoscopic rather than microscopic approach for potentially superior preservation of pituitary function 1
• Surgeon experience is more important than surgical technique 1
• Post-operative monitoring: Strict fluid and electrolyte balance monitoring is essential to detect complications like diabetes insipidus (26%) and SIADH (14%) 1

Radiotherapy Indications

• Primary indication: When tumor is symptomatic, growing, resistant to medical therapy, and surgically inaccessible 1
• Recommended protocol: External beam fractionated radiotherapy at 45-50.4 Gy in 1.8 Gy daily fractions 1
• Preferred modality: Proton beam therapy where available, or highly conformal photon therapy 1
• Single-fraction radiosurgery: May be appropriate in older patients in specific circumstances 1

Special Considerations

Giant Pituitary Adenomas

• Comprise 6-10% of all pituitary tumors 6
• Often require multimodal therapy combining surgery, medical treatment, and radiotherapy 6

Genetic Factors

• Nearly 50% of childhood-onset GH-secreting adenomas have identifiable genetic causes 1
• Common genetic abnormalities: AIP mutations (29% of gigantism cases), GPR101 duplication (10%) 1
• Genetic testing results should guide screening of family members 1

Post-Treatment Surveillance

• Non-functioning microadenomas: Follow for 1-3 years, can stop if stable 1
• Macroadenomas: Lifelong clinical surveillance with individualized MRI schedule 1
• Functioning adenomas: Regular hormonal assessments based on adenoma type 1

Pitfalls and Caveats

• Pituitary apoplexy requires urgent management; pediatric cases may be more severe than adult cases 1
• Changes in water metabolism are common complications of pituitary surgery; close monitoring is essential 1
• Repeated gadolinium administration for MRI follow-up raises concerns about deposition; consider unenhanced sequences during follow-up 1
• Physiological pubertal pituitary hypertrophy can mimic microadenomas in children and adolescents 1