Pituitary Adenoma

• primarily from anterior pituitary, 3rd-4th decades, M=F

• incidence in autopsy studies approximately 20%

• Classification

  • microadenoma <1 cm; macroadenoma ≥1 cm

  • endocrine active (functional/secretory) vs. inactive (non-functional)

• differential: parasellar tumours (e.g. craniopharyngioma, tuberculum sellae meningioma), carotid aneurysm

Clinical Features

• mass effects

  • H/A

  • bitemporal hemianopsia (compression of optic chiasm)

  • CN III, IV, V1, V2, VI palsy (compression of cavernous sinus)

• endocrine effects

  • hyperprolactinemia (prolactinoma): infertility, amenorrhea, galactorrhea, decreased libido

  • ACTH production: Cushing’s disease, hyperpigmentation

  • GH production: acromegaly/gigantism

  • panhypopituitarism (hypothyroidism, hypoadrenalism, hypogonadism)

  • associated MEN-1 syndrome

  • diabetes insipidus

• pituitary apoplexy (sudden expansion of mass due to hemorrhage or necrosis)

  • abrupt onset H/A, visual disturbances, ophthalmoplegia, reduced mental status, and panhypopituitarism

  • CSF rhinorrhea and seizures (rare)

  • signs and symptoms of subarachnoid hemorrhage (rare)

Investigations

• formal visual fields, CN testing

• endocrine tests (prolactin level, TSH, 8 AM cortisol, fasting glucose, FSH/LH, IGF-1), electrolytes, urine electrolytes, and osmolarity

• imaging (MRI with and without contrast)

Treatment

• Medical

  • for apoplexy: rapid corticosteroid administration ± surgical decompression

  • for prolactinoma: dopamine agonists (e.g. bromocriptine)

  • for Cushing's: serotonin antagonist (cyproheptadine), inhibition of cortisol production (ketoconazole)

  • for acromegaly: somatostatin analogue (octreotide) ± bromocriptine

  • endocrine replacement therapy

• Surgical

  • trans-sphenoidal, trans-ethmoidal, trans-cranial approaches for non-secreting adenomas causing mass effect and Cushing/acromegaly (50% cure rate)