Pituitary Tumours
Definition
Pituitary tumours account for ~10–15% of all intracranial neoplasms. [Ref]
Most are benign, different types of pituitary tumours: [Ref]
- Pituitary adenomas (~95%)
- Craniopharyngiomas (~4%)
Pituitary Adenomas
Definition
Pituitary adenomas are benign tumours of the pituitary gland, which most commonly arise from the anterior pituitary gland.
Aetiology
~95% cases are sporadic. [Ref]
~5% has a genetic / familial association: [Ref]
- MEN 1
- Carney complex
- Familial isolated pituitary adenoma syndrome
Classification
There are 2 main classification systems: [Ref]
- By size:
- <1cm = microadenoma
- ≥1cm = macroadenoma
- By functional status
- Functional adenomas secrete excessive pituitary hormones
- Non-functional adenomas do not produce hormones
Types of functional adenomas: [Ref]
| Origin | Relative frequency | Consequences |
|---|---|---|
| Lactoroph (prolactinoma) | ~50% | Secretes prolactin → hyperprolactinaemia |
| Somatotroph adenoma | ~10% | Secretes growth hormone → acromegaly / gigantism |
| Corticotroph adenoma | ~5% | Secretes ACTH → Cushing’s disease |
| Thyrotroph adenoma | <2% | Secretes TSH → secondary hyperthyroidism |
| Gonadotroph adenoma | Rare | Secretes LH and FSH |
The most common type of pituitary adenoma is prolactinoma.
Clinical Features
Peak incidence: 35-60 y/o
Clinical features depend on the tumour size and functional status [Ref]
- Microadenomas are typically asymptomatic
- Non-functional adenomas present with symptoms of mass effect
- Functional adenomas present with symptoms of mass effect and symptoms of hormone excess
Symptoms of Mass Effect
- Headache
- Visual disturbances (most common: bitemporal hemianopia)
- Cranial nerve palsies (if the tumour extends into the cavernous sinus)
- Hypopituitarism
Symptoms of Hormone Excess
Depends on the type of functional adenoma, see separate articles:
- Prolactinoma → see hyperprolactinaemia
- Somatotroph (GH-secreting tumour) → see acromegaly
- Corticotroph (ACTH-secreting tumour) → see Cushing’s syndrome
- Thyrotroph (TSH-secreting tumour) → see hyperthyroidism and thyrotoxicosis
Investigation and Diagnosis
Imaging of choice: pituitary MRI [Ref]
- Typically, a solid homogenous mass in the suprasellar region, with no calcifications (presence of calcification is usually in craniopharyngioma)
Biochemical testing (to evaluate for both hormone hypersecretion and hypopituitarism): [Ref]
| Purpose | Recommend testing |
|---|---|
| Testing for prolactinoma | Serum prolactin level
See hyperprolactinaemia for more details |
| Testing for acromegaly (GH-secreting tumour) | Serum IGF-1 level and OGTT
See acromegaly for more details |
| Testing for Cushing’s disease (ACTH-secreting tumour) | Midnight salivary cortisol / 24-hour urinary free cortisol / dexamethasone suppression test
See Cushing’s syndrome for more details |
| Testing for TSH-secreting tumour | TFT
See hyperthyroidism and thyrotoxicosis for more details |
| Assessment of hypopituitarism | Standard panel to evaluate for hypopituitarism (may overlap with the above tests):
Gold standard dynamic test: insulin stress test (assess for both adrenal and growth hormone axes) See the Hypopituitarism article for more information |
Formal visual field testing is also recommended for macroadenomas or lesions near the optic chiasm. [Ref]
Management
Management depends on the type of pituitary adenoma: [Ref]
| Type | 1st line management | 2nd line management |
|---|---|---|
| Non-functional adenoma | If asymptomatic → observation
If symptomatic → trans-sphenoidal surgery |
|
| Prolactinoma | Medical therapy with dopamine agonist
|
Trans-sphenoidal surgery |
| GH-secreting adenoma (acromegaly) | Trans-sphenoidal surgery | Medical therapy:
|
| ACTH-secreting adenoma (Cushing’s disease) | Medical therapy:
|
|
| TSH-secreting adenoma | Achieve euthyroid first, then trans-sphenoidal surgery (to reduce risk of thyroid storm) |
|
Dopamine agonists such as cabergoline are primarily used for prolactin-secreting pituitary adenomas, but they are also considered suitable second-line or adjunctive therapy for other types of hormone-secreting pituitary adenomas, although with less robust efficacy.
Craniopharyngiomas
Definition
Benign epithelial tumour arising from the remnant of the Rathke pouch, located in the sella and suprasellar region.
Craniopharyngioma is the most common childhood supratentorial tumour.
Clinical Features
Peak incidence: 5-14 y/o, and 50-74 y/o (bimodal distribution) [Ref]
Main clinical features: [Ref]
- Headache
- Visual impairment – classically bitemporal hemianopia
- Signs of raised ICP (e.g. nausea, vomiting, papilloedema)
Other clinical features of compression: [Ref]
| Compressed structure | Consequence |
|---|---|
| Pituitary gland | Causes hypopituitarism. Typical presentation in children:
|
| Hypothalamic nuclei (ventromedial) |
|
| Pituitary stalk |
|
| Interventricular foramina and/or aqueduct |
|
Craniopharyngiomas are often larger, cystic, and more infiltrative tumours located in the sellar and suprasellar region, frequently involving adjacent structures, and therefore commonly cause significant compression symptoms.
On the contrary, pituitary adenomas tend to be smaller and less invasive, causing less widespread compression.
In children presenting with headache + bitemporal hemianopia, craniopharyngioma is generally more likely than pituitary adenoma. Pituitary adenomas are rarer in children compared to adults
Investigation and Diagnosis
Imaging modality of choice: MRI [Ref]
- Typically, a mixed cystic-solid heterogeneous mass in the sellar and suprasellar region
- Calcification is common
- Compression of surrounding structures is common
Management
The management is complex and requires an MDT approach, including neurosurgery, endocrinology, neuro-oncology, radiation oncology, and neuro-ophthalmology.
An individualised approach to balance tumour control with preservation of hypothalamic, pituitary and visual function is necessary.