Pituitary adenoma

Tumors of the pituitary gland

Pituitary adenoma
Bitempvf labelled.png
Visual field loss in bitemporal hemianopsia: a tumor—typically a pituitary adenoma—compressing the optic chiasm.
Specialty	Oncology, endocrinology
Symptoms	Headaches, vision loss, hormonal imbalances
Complications	Acromegaly, Cushing’s disease, hypopituitarism
Usual onset	Variable
Duration	Chronic
Types	Microadenoma, macroadenoma
Causes	Genetic mutations, sporadic development
Risk factors	Family history, Multiple endocrine neoplasia (MEN), Carney complex
Diagnosis	MRI, CT scan, hormone level tests
Differential diagnosis	Craniopharyngioma, meningioma
Prevention	None known
Treatment	Surgery, medication, radiation therapy
Medication	Cabergoline, bromocriptine, octreotide
Prognosis	Generally favorable with treatment
Frequency	~17% of the population (mostly asymptomatic)

Pituitary adenomas are benign tumors that develop in the pituitary gland. They account for 10–25% of all intracranial tumors, with an estimated prevalence of 17%.

Classification

Pituitary adenomas are categorized based on size, hormonal activity, and invasiveness:

• Size-based classification:
• Microadenomas (<10 mm) – Often asymptomatic and discovered incidentally.
• Macroadenomas (≥10 mm) – More likely to cause symptoms due to compression of nearby structures.

• Hormonal classification:
• Functional adenomas – Secrete hormones, leading to conditions such as:
• Prolactinoma (↑Prolactin) – Causes galactorrhea, infertility.
• Somatotrophic adenoma (↑Growth hormone) – Leads to acromegaly or gigantism.
• Corticotrophic adenoma (↑ACTH) – Causes Cushing’s disease.
• Thyrotrophic adenoma (↑TSH) – Rare, can lead to hyperthyroidism.
• Gonadotrophic adenoma (↑FSH/LH) – Usually asymptomatic.
• Nonfunctional adenomas – Do not secrete hormones but can cause mass effects.

• Invasiveness classification:
• Benign adenoma – Well-circumscribed, non-invasive.
• Invasive adenoma – Invades nearby tissues (e.g., cavernous sinus).
• Pituitary carcinoma – Extremely rare, metastasizing.

Symptoms

Pituitary adenomas may present with hormonal symptoms or mass effects:

Hormonal Symptoms

• Prolactinoma: Infertility, decreased libido, menstrual irregularities, galactorrhea.
• GH-secreting tumors: Acromegaly (enlarged extremities, coarsened facial features) or gigantism (excessive growth in children).
• ACTH-secreting tumors: Cushing’s disease (weight gain, moon face, purple striae).
• TSH-secreting tumors: Hyperthyroidism (nervousness, weight loss, heat intolerance).
• Hypopituitarism (from large adenomas): Fatigue, cold intolerance, hypotension.

Mass Effect Symptoms

• Headache
• Visual disturbances (e.g., bitemporal hemianopsia from optic chiasm compression)
• Cranial nerve palsies (from cavernous sinus invasion)
• Hydrocephalus (rare, in large tumors)

Diagnosis

Pituitary adenomas are diagnosed using a combination of imaging and hormone testing:

• Imaging:
• MRI (gold standard) – Best for detecting small tumors.
• CT scan – Used if MRI is unavailable.

• Hormone Testing:
• Prolactin levels – For suspected prolactinomas.
• IGF-1 and glucose suppression test – For GH-secreting tumors.
• 24-hour urine cortisol or dexamethasone suppression test – For Cushing’s disease.

Treatment

Treatment depends on tumor type, size, and symptoms:

1. Medication

• Prolactinomas: Dopamine agonists (e.g., cabergoline, bromocriptine) reduce tumor size and normalize prolactin levels.
• Acromegaly (GH-secreting tumors): Somatostatin analogs (octreotide, lanreotide) or GH receptor antagonists (pegvisomant).
• Cushing’s disease (ACTH-secreting tumors): Ketoconazole, metyrapone (cortisol synthesis inhibitors).

2. Surgery

• Transsphenoidal surgery (preferred) – Minimally invasive endoscopic removal via the nasal cavity.
• Craniotomy – Required for large, invasive tumors.

3. Radiation Therapy

• Stereotactic radiosurgery (Gamma Knife, CyberKnife) – Used for residual or recurrent tumors.
• External beam radiation – For aggressive adenomas that cannot be fully resected.

Prognosis

• Microadenomas have an excellent prognosis.
• Macroadenomas can cause permanent endocrine dysfunction if not treated early.
• Recurrence risk depends on size, invasiveness, and treatment success.

Epidemiology

• Pituitary adenomas affect ~1 in 6 people, though many remain undiagnosed.
• Clinically significant cases requiring treatment occur in ~1 in 1,000 people.

Related Conditions

• Acromegaly
• Cushing’s syndrome
• Prolactinoma
• Hypopituitarism

External Links

• NIH: Pituitary Tumors
• Pituitary Network Association