Sellar Region Lesions

• ~30 different lesions occur in or around the pituitary gland

• Five lesions make up the majority of lesions (~75%)

o Macroadenoma

o Meningioma

o Aneurysm

o Craniopharyngioma

o Astrocytoma

• Three key anatomical divisions

o Intrasellar

o Suprasellar

o Infundibular stalk

Pituitary adenoma

Definitions

• Size
• Microadenoma <10mm
• Macroadenoma >/= 10mm
• Giant >30-40mm

• Aggressive
• Based on Clinical features
• High rates of recurrence and/or resistance to conventional treatment
• Non-metastatic
• Invasive
• Defined by radiological/surgical/histopathological findings
• Invasion into sphenoid sinus/cavernous sinus
• Suprasellar extension does not = invasive
• Knosp grade 3 and 4
• 25-55% of pituitary tumours

• Atypical
• Atypical morphological features
• “invasive growth”, elevated mitotic index, high Ki-67 (MIB-1) index, p53 staining
• 2.7%-15% of adenomas

• Pituitary carcinoma
• Defined by cranio-spinal dissemination or systemic metastasis
• 0.2% of pituitary tumours

Epidemiology

• Peak incidence 30-60yrs

Pathology

• 2/3 secrete hormone
• 48% prolactin
• 10% GH
• 6% Corticotropin (ACTH)
• 1% Thyrotropin (TSH)
• 1/3 non-secreting

·

Adenoma Cell Origin	Frequency (%)	Hormone Product	Clinical Syndrome
Non-functioning	~33
Null cell	12	None	Pituitary failure
Oncocytoma	13	None	Pituitary failure
Functional	~66
Lactotrope/Prolactin	27	PRL	Hypogonadism, galactorrhea
Somatotrope	13	GH	Acromegaly/gigantism
Gonadotrope	10	FSH, LH, subunits	Silent or hypogonadism
Corticotrope	9.6	ACTH	Cushing's disease
Mixed growth hormone and prolactin cell	3.5	GH, PRL	Acromegaly, hypogonadism, galactorrhea
Acidophil stem cell	1.5	PRL, GH	Hypogonadism, galactorrhea, acromegaly
Mammosomatotrope	1	PRL, GH	Hypogonadism, galactorrhea, acromegaly
Thyrotrope	1	TSH	Thyrotoxicosis
Other plurihormonal cell		Any	Mixed

Diagnosis

Imaging

• CT
• Moderate but heterogenous enhancement

• MRI
• Macroadenoma
• T1 – isointense with cortex
• T2 – isointense (sometimes some heterogenous increased signal)
• Contrast – strong but heterogenous contrast enhancement
• Other structures:
• Cysts 15-20%
• Haemorrhage 10%
• Calcium 1-2%
• Microadenoma
• T1 – isointense
• Contrast - Hypointense relative to surrounding gland (enhance slowly)
• Dynamic T1 +C scanning can help differentiate

Hormonal testing

Physiology

Six major hormones:

	Cells	Stimulating	Inhibitors
Prolactin (PRL)	Lactotrope	Oestrogen, TRH, VIP	Dopamine (dominant)	Milk production
Growth hormone (GH)	Somatotrope	GHRH, Ghrelin	Somatostatin, IGF-I	IGF-I production Growth Insulin antagonism
Adrenocorticotropin hormone (ACTH)	Corticotrope	CRH, AVP, gp 130 cytokines	Glucocorticoids	Steroids
Leuteinizing hormone (LH)	Gonadotroph	GnRH, activins, oestrogen	Sex steroids, inhibin	Sex steroid production Germ cell maturation Follicle growth
Follicle-Stimulating hormone (FSH)
Thyroid stimulating hormone (TSH)	Thyrotrope	TRH	T3/4, dopamine, somatostatin, glucocorticoids	Thyroid hormone

Screening battery

· Prolactin

· IGF-1

· LH/FSH

· Testosterone/Oestrogen

· ACTH/morning cortisol

· TFTs