Pituitary Tumors

Pituitary tumors account for approximately 10% of all intracranial tumors. Most are benign pituitary adenomas that arise from the anterior pituitary gland. Clinical manifestations result from local mass effect on surrounding structures, particularly the optic chiasm, or from hypersecretion or hyposecretion of pituitary hormones. Management requires a multidisciplinary approach involving endocrinology, neurosurgery, ophthalmology, radiation oncology, and pathology. Early diagnosis and appropriate treatment help preserve neurological function, restore endocrine balance, and improve quality of life.

Epidemiology

Pituitary tumors account for approximately 10% of intracranial tumors. They commonly occur in adults between 30 and 60 years of age and affect both sexes. Functional (hormone-secreting) and non-functional adenomas are the most common types. Prolactinomas are the most frequently encountered functional pituitary tumors.

Risk factors

Risk factors for pituitary tumors include:

• Increasing age

• Multiple Endocrine Neoplasia type 1 (MEN1)

• Family history of pituitary adenoma

• Genetic syndromes affecting endocrine glands

• Previous cranial irradiation (rare)

Pathophysiology

Pituitary tumors arise from adenohypophyseal cells and may be classified as functional (hormone-secreting) or non-functional.

Clinical manifestations occur through:

• Compression of the optic chiasm causing visual field defects.

• Compression of surrounding brain structures resulting in headache and neurological deficits.

• Hypersecretion of pituitary hormones causing endocrine syndromes such as prolactinoma, acromegaly, and Cushing's disease.

• Compression of normal pituitary tissue resulting in hypopituitarism.

• Invasion of adjacent structures, including the cavernous sinus, in large tumors.

Clinical presentation

Patients may present with symptoms related to local tumor expansion, hormone hypersecretion, or pituitary hormone deficiency. The presentation varies according to tumor size and functional status.

Symptoms

• Chronic headache

• Loss of vision

• Progressive visual field impairment

• Focal neurological deficits

• Menstrual irregularities or amenorrhoea

• Galactorrhoea

• Reduced libido and infertility

• Erectile dysfunction

• Features of acromegaly

• Features of Cushing's disease

• Symptoms of hypopituitarism including fatigue, weight loss, and cold intolerance

Clinical signs

• Bitemporal hemianopia

• Reduced visual acuity

• Cranial nerve palsies in tumors invading the cavernous sinus

• Features of acromegaly

• Features of hypercortisolism

• Galactorrhoea

• Features of hypopituitarism

• Focal neurological deficits

Differential diagnosis

• Craniopharyngioma

• Meningioma

• Rathke's cleft cyst

• Hypothalamic tumors

• Intracranial germ cell tumors

• Metastatic brain tumors

• Optic pathway glioma

• Aneurysm involving the parasellar region

Diagnostic criteria

The diagnosis is based on compatible clinical findings, biochemical evidence of pituitary hormone abnormalities where appropriate, and characteristic neuroimaging findings.

Diagnosis is established by:

• Clinical features suggestive of pituitary mass effect or endocrine dysfunction.

• MRI or CT demonstrating a pituitary lesion.

• Endocrine evaluation confirming hormone hypersecretion or hypopituitarism.

• Histopathological confirmation following surgical excision where tissue is obtained.

Investigations

• Full blood picture (FBP)

• Serum electrolytes

• Anterior pituitary hormone profile

• CT scan or MRI of the brain

• CT angiography or MR angiography

• Visual field assessment

• Histopathological examination following surgery

Management

Management depends on tumor size, functional status, endocrine abnormalities, visual impairment, and suitability for surgery.

Initial management includes:

• Assess airway, breathing, and circulation in critically ill patients.

• Assess neurological status and visual function.

• Evaluate pituitary hormone function.

• Manage acute endocrine abnormalities where present.

• Determine whether the tumor is functional or non-functional.

• Plan definitive treatment through a multidisciplinary team.

Non-pharmacological treatment

Surgical management

• Surgical resection is the primary treatment for most pituitary tumors except prolactinomas, which are usually managed medically.

• The trans-sphenoidal approach (endoscopic or microsurgical) is the preferred surgical technique because it is safer and better tolerated.

• Surgical resection is frequently subtotal in large tumors or tumors invading the cavernous sinuses.

• Histopathological examination should be performed on all resected specimens.

• Patients should be monitored for postoperative hypopituitarism, which occurs in approximately 12% of patients.

Radiotherapy

Radiotherapy is indicated for:

• Residual tumor following subtotal resection.

• Recurrent pituitary tumors.

• Persistently elevated circulating hormone levels after surgery.

• Inoperable tumors.

Radiotherapy provides excellent control of tumor growth (>95%) but is less effective in reducing circulating hormone levels in functional tumors.

Follow-up MRI should be performed 3 months after surgery to assess residual tumor.

Pharmacological treatment

Functional tumors

Prolactinomas

Initial treatment should be with dopamine receptor agonists.

• Bromocriptine – 2.5 mg – PO – every 8 hours.

OR

• Cabergoline – 0.25 mg – PO – once or twice weekly – titrate according to prolactin levels measured every 2 weeks, aiming to maintain prolactin (PRL) <30 ng/mL.

Cushing's disease

Surgical management is recommended.

When surgery is not possible:

• Metyrapone – 250 mg – PO – once daily – dose may be escalated according to clinical response.

Acromegaly

Somatostatin analogues may be used.

• Octreotide SR – administer according to local treatment protocol.

Treatment efficacy should be assessed by:

• Basal growth hormone (GH) level <2.5 ng/mL.

• Glucose-suppressed GH <1.5 ng/mL.

• Normalization of serum insulin-like growth factor-1 (IGF-1).

Management according to underlying cause

Non-functional pituitary tumors

• Surgical resection is the preferred treatment.

• Radiotherapy may be required following subtotal resection or recurrence.

Prolactinomas

• Initial treatment with dopamine receptor agonists.

• Surgery is reserved for patients with drug intolerance, resistance, or significant compressive symptoms.

Cushing's disease

• Trans-sphenoidal surgery is the treatment of choice.

• Metyrapone may be considered when surgery is contraindicated or unavailable.

Acromegaly

• Surgical resection where feasible.

• Somatostatin analogue therapy when indicated.

• Radiotherapy for persistent or recurrent disease.

Postoperative complications

Diabetes Insipidus

Characterized by excessive urine output due to ADH deficiency, usually occurring immediately after surgery.

• Desmopressin – 0.05 mg – PO – every 12 hours – daily, titrated according to clinical response.

Syndrome of Inappropriate

Antidiuretic Hormone Secretion (SIADH)

Characterized by decreased urine output and hyponatraemia due to excessive ADH secretion, usually occurring immediately after surgery.

• Correct hyponatraemia.

• Furosemide – 40 mg – PO – according to clinical response.

Cerebral Salt Wasting (CSW)

Characterized by excessive urinary sodium loss and hyponatraemia, usually occurring immediately after surgery.

• Correct hyponatraemia with hypertonic 3% saline.

• Fludrocortisone – 0.05–0.1 mg – PO – every 12 hours – daily.

Referral

Refer all patients with suspected or confirmed pituitary tumors to a neurosurgical and endocrinology specialist.

Urgent referral is indicated for patients with:

• Progressive visual loss

• Pituitary apoplexy

• Acute deterioration in consciousness

• Severe endocrine dysfunction

• Large tumors causing significant mass effect

• Progressive neurological deficits

• Recurrent or residual tumors requiring radiotherapy

Complications

• Hypopituitarism

• Visual impairment

• Permanent visual loss

• Diabetes insipidus

• Syndrome of inappropriate antidiuretic hormone secretion (SIADH)

• Cerebral salt wasting (CSW)

• Cerebrospinal fluid leak

• Tumor recurrence

• Pituitary apoplexy

• Postoperative infection

Prognosis

The prognosis depends on tumor size, histological subtype, hormone secretion, completeness of surgical resection, and response to treatment. Most pituitary adenomas are benign and have favorable long-term outcomes when appropriately treated. Functional tumors often demonstrate good biochemical control with surgery and/or medical therapy. Long-term endocrine follow-up is essential because pituitary hypofunction may develop years after surgery or radiotherapy.

Prevention

There are no established measures to prevent pituitary tumors. Early recognition of persistent headache, visual disturbances, or endocrine abnormalities facilitates prompt diagnosis and treatment. Patients treated with surgery or radiotherapy should undergo lifelong endocrine surveillance because pituitary hypofunction may occur up to 15 years after treatment.