• Clinical science

Pituitary adenoma

Abstract

Pituitary adenomas are benign tumors that often arise sporadically from the anterior pituitary gland. They are classified based on their size as microadenomas or macroadenomas, and whether they produce hormones as secretory (functional) and non-secretory (non-functioning) adenomas. Secretory adenomas produce the pituitary hormone of the corresponding cell type, which results in a state of hyperpituitarism. Non-secretory macroadenomas, however, destroy the surrounding normal pituitary tissue and result in hypopituitarism. Additionally, large macroadenomas compress the optic chiasm and can thus present with signs of mass effect such as bitemporal hemianopsia. The investigation of choice is a contrast-enhanced cranial MRI, which reveals an intrasellar mass. Assays of pituitary hormones are used to evaluate the patient for endocrine abnormalities, and perimetry is required to document visual field defects. Transsphenoidal surgical resection is the first-line therapy for most pituitary adenomas; however, non-secretory microadenomas generally only require follow-up, and prolactin-producing pituitary adenomas (prolactinomas) are best treated with dopamine agonists (e.g., bromocriptine, cabergoline). Pituitary irradiation is indicated only if the pituitary adenomas recur and/or if surgical therapy is contraindicated.

Epidemiology

References:[1]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

References:[2]

Pathophysiology

Type of secretory pituitary adenomas

Relative frequency (as a percentage of all pituitary adenomas)

Histology Pathophysiology
Lactotroph adenoma (prolactinoma) ∼ 40% Hyperprolactinemia
Somatroph adenoma ∼ 15%
  • Acidophilic
  • Express PIT-1
Growth hormoneacromegaly/gigantism
Corticotroph adenoma (Cushing's disease) ∼ 5%
  • Basophilic
  • Stain positive with PAS
ACTHsecondary hypercortisolism
Thyrotroph adenoma ∼ 1%[3]
  • Basophilic
TSH → secondary hyperthyroidism

Prolactinomas are the most common pituitary adenomas!

References:[3][4]

Clinical features

The symptoms associated with pituitary adenomas depend on the size of the tumor and whether the tumor produces hormones!

Type of pituitary adenoma Secretory adenomas Non-secretory adenomas
Microadenomas
  • Asymptomatic
Macroadenomas

References:[4]

Diagnostics

References:[3][2][4]

Differential diagnoses

References:[4]

The differential diagnoses listed here are not exhaustive.

Treatment

Following transsphenoidal resection and/or pituitary irradiation, patients may develop hypopituitarism and potentially require lifelong hormone replacement therapy!References:[2][1][1][5][6]