How are pituitary microadenomas treated?

Treatment of Pituitary Microadenomas

For pituitary microadenomas, treatment should be tailored to the specific type of adenoma, with transsphenoidal surgery being the definitive treatment of choice for most types except prolactinomas, which are primarily treated with dopamine agonists. 1

Treatment Based on Adenoma Type

Prolactinomas

• Medical therapy with dopamine agonists (bromocriptine or cabergoline) is the first-line treatment for prolactin-secreting microadenomas 2, 3
• Bromocriptine has been established as effective for prolactin-secreting pituitary adenomas in patients aged 16 and older, with evidence supporting its use in children aged 11-15 years 2
• Treatment leads to normalization of prolactin levels and tumor shrinkage in most cases 2
• In a limited study of 14 children and adolescents (11-15 years) with prolactin-secreting adenomas, 9 had successful outcomes with bromocriptine, 3 had partial responses, and 2 failed to respond 2

Growth Hormone-Secreting Microadenomas (Somatotropinomas)

• Transsphenoidal surgery is the first-line treatment for GH-secreting microadenomas 4, 3
• If surgery fails to normalize GH levels, somatostatin analogs or GH-receptor antagonists (pegvisomant) may be used 4, 5

ACTH-Secreting Microadenomas (Corticotropinomas)

• Transsphenoidal surgery is the primary therapy, even if no microadenoma is visible on MRI 4, 6
• If surgery is unsuccessful, radiotherapy may be considered, with medical therapy (adrenal steroidogenesis inhibitors) used while awaiting the effects of radiation 4, 7

TSH-Secreting Microadenomas (Thyrotropinomas)

• Transsphenoidal surgery is the primary treatment option 1
• Medical therapy with somatostatin analogs may be used if surgery is not curative 1
• Regular monitoring with thyroid function tests and MRI surveillance is recommended 1

Non-Functioning Microadenomas

• For incidentally discovered non-functioning microadenomas, observation with MRI surveillance is appropriate 1
• MRI surveillance should be performed at 12 months and, if stable, at 1-2 year intervals for 3 years with gradual reduction thereafter 1
• Microadenomas generally follow a benign course and radiological surveillance can cease after 1-3 years if stable 1

Surgical Approach

• If surgery is indicated, transsphenoidal surgery is the technique of choice, even in patients with incompletely pneumatized sphenoid sinuses 1
• Endoscopic rather than microscopic transsphenoidal surgery should be considered for potentially superior efficacy in preserving pituitary function 1
• Surgery should be performed by experienced pituitary surgeons in centers with extensive experience (at least 50 pituitary operations per year) 1
• Strict fluid and electrolyte balance monitoring is essential peri-operatively and post-operatively 1

Post-Surgical Considerations

• Water metabolism changes and arginine vasopressin regulation disturbances are common complications after surgery 1
• Post-operative AVP deficiency (diabetes insipidus) occurs in approximately 26% of children undergoing transsphenoidal surgery 1
• SIADH (syndrome of inappropriate antidiuretic hormone secretion) occurs in about 14% of pediatric cases 1
• Risk factors for these complications include female sex, cerebrospinal fluid leak, surgical drain placement, posterior pituitary invasion by tumor, or manipulation of the posterior pituitary during surgery 1

Follow-up and Monitoring

• For non-functioning microadenomas, MRI surveillance at 12 months and then at 1-2 year intervals for 3 years if stable 1
• For functioning microadenomas, follow-up should include regular hormone level assessments specific to the tumor type 1
• After surgery for functioning microadenomas, post-operative MRI surveillance should be performed at 3 and 6 months, and 1,2,3, and 5 years 1

Special Considerations for Children and Adolescents

• Children with pituitary adenomas should be treated by a pituitary-specific multidisciplinary team with experts from both pediatric and adult practice 1
• The impact of treatment on the developing body and brain carries greater consequences for children and young people 1
• Genetic testing should be considered, as certain genetic conditions (MEN1, AIP mutations, DICER1 syndrome) are associated with pituitary adenomas in children 1

Remember that early diagnosis and appropriate treatment are crucial to reduce morbidity and mortality associated with pituitary microadenomas, especially in children and young people where the long-term impact on quality of life is particularly important.