Pituitary and Sellar Lesions

The *pituitary gland*, located in the **sella turcica is a critical endocrine organ that regulates hormones controlling growth, metabolism, reproduction, and stress response. It is further controlled by releasing or inhibitory hormones from Hypothalamus. Pituitary gland has two lobes anterior and posterior lobe. There are 6 hormones that release from anterior lobe and 2 from posterior lobe.

*Sellar Lesions* can arise from the pituitary itself or surrounding structures and may cause hormonal dysfunction (excess secretion or deficiency) or local mass effects leading to visual impairment, cranial nerve palsies, hydrocephalus, stroke.

Types of Pituitary / Sellar Lesions

1. Pituitary Adenomas (Most Common)

– Benign tumors of pituitary cells, classified by:

– Size:

Microadenoma* (<1 cm)
Macroadenoma* (≥1cm)
Hormone secretion
Functional (secreting) adenomas that secrete active hormones like prolactinoma
Non-functional (non-secreting): they usually cause symptoma due to mass effect. Mostly patients remain asymptomatic till adenoma acheive a certain size and causes mass effect.
Classification on the basis of electron microscopy *

– On the basis of light microscopy

Type	Hormone Excess	Clinical Features
Prolactinoma	Prolactin	Galactorrhea, secondary amenorrhea, infertility, erectile dysfunction (ED)
Somatotroph	GH (Growth Hormone)	Acromegaly (adults), gigantism (children)
Corticotroph	ACTH	Cushing’s disease (central obesity, moon face, striae)
Thyrotroph	TSH	Secondary hyperthyroidism (rare)
Gonadotroph	FSH / LH	Usually non-functional (mass effects)

Non-Functional Adenomas

Non-functional pituitary adenomas do not secrete biologically active hormones. They usually present with mass effects, which include:

Headaches – due to stretching of the dura
Visual field defects – classically bitemporal hemianopia from compression of the optic chiasm
Hypopituitarism – compression of normal pituitary tissue leading to ↓ ACTH, TSH, FSH/LH, GH
Cranial nerve palsies – involving CN III, IV, VI if the cavernous sinus is affected
Hydrocephalus – caused by suprasellar extension and compression of the third ventricle

2. Craniopharyngioma

Nature: Benign, slow-growing cystic or solid tumor, arising from remnants of Rathke’s pouch
Epidemiology: Most common in children and young adults
Types:
1. Adamantinomatous – more common in children
2. Papillary – usually seen in adults

Clinical Features (Symptoms):

Headache
Visual impairment – due to compression of the optic chiasm
Endocrine dysfunction:
- Growth failure in children
- Hypothyroidism
- ADH deficiency → Diabetes insipidus
- Hypogonadism

3. Rathke’s Cleft Cyst

Benign, fluid-filled cyst arising from remnant of Rathke’s pouch
Often asymptomatic, but when symptomatic, it may mimic pituitary adenoma or craniopharyngioma

4. Meningioma

Arises from sellar/parasellar meninges
Slow-growing, compresses pituitary & optic structures

5. Pituitary Apoplexy

Sudden hemorrhage or infarction of a pituitary adenoma (or sometimes normal pituitary) → causes acute neurological or endocrine dysfunction
Medical Emergency!
Symptoms:
- Severe headache (thunderclap onset)
- Vision loss (optic nerve/chiasm compression)
- Ophthalmoplegia (cranial nerves III, IV, VI palsy)
- Hypotension (ACTH deficiency → adrenal crisis)
Treatment:
- High-dose glucocorticoids (IV hydrocortisone)
- Endoscopic transsphenoidal decompression in many cases

6. Metastasis to Pituitary

Rare, but can occur from breast, lung, prostate cancers

7. Aneurysm / Inflammatory Lesions

Can mimic pituitary masses
Examples: Inflammation (hypophysitis)

Diagnosis of Sellar Lesions

1. Pituitary Hormonal Workup

(to assess hypersecretion or deficiency)

Prolactin
IGF-1 (GH)
ACTH / Cortisol
TSH / Free T4
FSH / LH
Testosterone / Estradiol

2. Imaging

MRI brain with pituitary protocol (gold standard)
Dynamic MRI brain (Pituitary gland) – most useful in detecting microadenomas
CT brain / CT angiogram – for surgical planning (e.g., visualization of sphenoid sinus pneumatization, detection of calcifications, pituitary apoplexy, or aneurysms)

3. Visual Field Testing

Treatment Approaches

Lesion	Management
Prolactinoma	Dopamine agonists (cabergoline, bromocriptine); surgical excision in selected cases
Other Functional Adenomas	Surgery – Endoscopic transsphenoidal or Transcranial approach
Non-Functional Adenoma	Surgery is the mainstay of treatment, especially if the patient is symptomatic

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