What is the recommended workup and treatment for a pituitary adenoma?

Workup and Treatment of Pituitary Adenomas

Pituitary adenomas require a comprehensive multidisciplinary approach with transsphenoidal surgery as the first-line treatment for most adenomas except prolactinomas, which are primarily treated with dopamine agonists like cabergoline. 1, 2, 3

Initial Diagnostic Workup

Imaging

• MRI of the pituitary gland:
  • Pre-contrast T1-weighted and T2-weighted sequences
  • Post-contrast with gadolinium enhancement (macrocyclic agents preferred)
  • 3-Tesla MRI if available for better resolution 1

Visual Assessment

• Visual acuity testing (logarithm of the minimum angle of resolution)
• Visual field testing (Goldmann perimetry preferred)
• Fundoscopy
• Consider optical coherence tomography for baseline assessment if severe deficits 1

Hormonal Evaluation

• Complete hormonal panel:
  • Serum prolactin
  • IGF-1 and GH suppression test
  • 24-hour urinary free cortisol and/or nocturnal salivary cortisol
  • TSH and free T4
  • FSH, LH, estradiol/testosterone 4, 2, 3

Additional Testing

• For suspected Cushing's disease: Consider bilateral inferior petrosal sinus sampling (BIPSS) 4
• Genetic testing if:
  • Family history of pituitary adenomas
  • Young age at presentation
  • Multiple endocrine neoplasia suspicion
  • Consider screening for MEN1, AIP, CABLES1, CDKN1B, and DICER1 mutations 1

Classification of Pituitary Adenomas

By Size

• Microadenomas: <10 mm
• Macroadenomas: ≥10 mm
• Giant adenomas: >4 cm 1, 2, 3

By Function

• Functioning adenomas (hormone-secreting):
  • Prolactinomas (32-66%)
  • Growth hormone-secreting (8-16%)
  • ACTH-secreting (2-6%)
  • TSH-secreting (1%)
• Non-functioning adenomas (15-54%) 2, 3

Treatment Approach

Prolactinomas

1. First-line: Medical therapy with dopamine agonists
   • Cabergoline (preferred) or bromocriptine 5, 2, 3
2. Second-line: Consider surgery if:
   • Resistance to medical therapy
   • Intolerance to dopamine agonists
   • Significant mass effect despite medical therapy 2, 3

All Other Functioning Adenomas

1. First-line: Transsphenoidal surgery
   • Endoscopic approach preferred over microscopic for better preservation of pituitary function 1
2. Second-line: Medical therapy based on adenoma type:
   • GH-secreting: Somatostatin analogs, pegvisomant, or cabergoline
   • ACTH-secreting: Ketoconazole, mifepristone, or pasireotide
   • TSH-secreting: Somatostatin analogs 1, 2, 3

Non-functioning Adenomas

1. Symptomatic (mass effect, hypopituitarism):
   • Transsphenoidal surgery 2, 3
2. Asymptomatic incidentalomas:
   • <10 mm: Observation with serial imaging
   • ≥10 mm or growing: Consider surgery 2, 6

Radiotherapy

• Indications:
  • Incomplete tumor resection
  • Recurrence after surgery
  • Uncontrolled growth despite medical therapy
  • Contraindication to surgery 1
• Options:
  • Conventional fractionated radiotherapy
  • Stereotactic radiosurgery
  • Proton beam therapy 4

Perioperative Management

• Strict fluid and electrolyte monitoring
• Watch for diabetes insipidus, SIADH, or triphasic response
• Monitor for hypopituitarism 1

Long-term Follow-up

• Lifelong monitoring for:
  • Tumor recurrence (can occur up to 15 years after treatment)
  • Hormonal status
  • Development of hypopituitarism
  • Visual function if previously affected 4
• After radiotherapy: Periodic assessment of radiation efficacy with temporary withdrawal of medical therapy 1
• Mental health monitoring (especially for Cushing's disease patients) 4

Special Considerations

Pediatric Patients

• Transsphenoidal surgery is safe and effective even with incompletely pneumatized sphenoid sinuses
• Consider transition planning to adult services 1

Genetic Syndromes

• MEN1: Higher risk of prolactinomas and non-functioning adenomas
• AIP mutations: Often associated with GH-secreting tumors
• DICER1: Associated with pituitary blastoma 1

Common Pitfalls to Avoid

1. Misdiagnosis: Consider differential diagnoses including craniopharyngioma, Rathke's cleft cyst, meningioma, and lymphocytic hypophysitis 4, 7

2. Inadequate hormonal evaluation: Always assess for both hormone hypersecretion and hypopituitarism 4, 2

3. Overlooking visual assessment: All macroadenomas require formal visual field testing 1, 4

4. Insufficient follow-up: Recurrences can occur many years after initial treatment 4

5. Ignoring mental health: Hormonal imbalances can significantly impact psychological wellbeing 4