Pathology of the Pituitary Gland Flashcards
What are the size classifications of pituitary tumours?
less/equal 1cm = microadenoma
>1cm = macroadenoma
What 2 structures can a non-functioning pituitary adenoma or a pituitary tumour compress?
Optic chiasma
Cranial Nerves 3,4,6
What cells are a pituitary adenoma derived form?
Cells from anterior pituitary
How are pituitary adenomas classified?
Cell type or hormone produced
What is the most common functional pituitary adenoma?
Prolactinoma
What are the other kinds of functional pituitary adenomas and what are their effects?
Growth hormone secreting adenoma - GH causes increase in IGF which stimulates growth of bone, cartilage and connective tissue giving gigantism or acromegaly
ACTH secreting adenoma - Leads to hypercortisolism, Cushing’s disease
What % of pituitary tumours are pituitary carcinoma?
<1%
List some causes of panhypopituitarism.
1y or metastatic tumours traumatic brain injury subarachnoid haemorrhage surgery or radiation granulomatous inflammation infarction/ haemorrhage (Sheehans syndrome) Hypothalamic lesions
Define panhypopituitarism.
Decreased secretion of all of the pituitary hormones.
What is a carinopharyngioma derived from?
Remants of Rathke’s pouch (makes anterior pituitary)
List 5 things about carinopharyngiomas.
Slow growing, often cystic, may calcify Some arise within the sella but most suprasellar Bimodal incidence (5-15, 60-70s) Headaches and visual disturbances Excellent prognosis - benign tumour
What are the 2 kinds of diabetes insipidus?
Central or nephrogenic
What is central diabetes insipidus?
ADH deficiency
Can be caused by trauma (including surgery), tumours and inflammatory disorders of hypothalamus and pituitary
What is nephrogenic diabetes insipidus?
Renal resistance to ADH effects
What does SIADH secretion mean?
Syndrome of Inappropriate ADH secretion
Ectopic production of ADH - paraneoplastic syndrome
With Acromagaly, which cancer are you at increased risk of?
Colon cancer
How do non-functioning pituitary adenomas arise?
Sporadic or associated with MEN1
Give some causes of prolactinoma.
Physiological: pregnancy, breast feeding, stress, sleep
Drugs (dopamin antagonists, anti-psychotics, antidepressants, oestrogen, coccaine)
hypothyroidism (2y prolactinoma)
Pituitary stalk lesion
How does a prolactinoma arise in a female?
Early presentation Galatorrhoea Menstrual irregularity Ammenorrhoea Infertility
How does a prolactinoma present in a male?
Late presentation Galactorrhoea visualy field abnormality headache impotence or ED Ant Pit malfunction
What investigations are required for a suspected prolactinoma?
Serum prolactin
MRI
Visual field (bitemporal hemianopia)
Pituitary function tests (several hormones)
How is a prolactinoma treated?
Dopamine agonists - Cabergoline, Metaclopramide - prolactin normaisation and tumour shrinkage
What treatment is required for acromegaly?
Pituitary surgery Retest GTT – if still>1mcg then needs drugs: Somatostain analogues: Octreotide Dopamine agonists: Cabergoline GH antagonist: Pegvisomant
How does acromegaly present?
Thickened skin and enlarged jaw and facial aspects
Sweating
Sleep apnoea/ snoring
Visual disturbance
Headaches – increased blood flow and tumour expansion
What causes acromegaly?
Anterior pituitary gland produces excess growth hormone
What is the definitive test for acromegaly?
glucose tolerance test: suppression test of GH – paradoxical rise in GH occurs: normal GH suppresses to 1mcg/l
What blood test can be useful in the aiding the diagnosis of acromegaly?
IGF1
What can panhypopituitarism lead to?
GH -- growth failure TSH -- hypothyroidism LH/FSH -- hypogonadism ACTH -- Hypoadrenal (ife-threatening) ADH -- Diabetes Insipidus
Give some symptoms and signs of panhypopituitarism.
Menstraul irregularities Infertility/ impotence Gynaecomastia (M) Loss of facial hair (M) Loss of axillary and pubic hair hypothyroid faces abdo obesity dry skin and hair growth retardation (children)
What drugs can be given for panhypopituitarism?
Thyroxine Hydorcortisone ADH GH (rarely given) OCP Testosterone for males (Sustanon, testogel)
What are the risks of testosterone replacement?
Prostate enlargment (not cancer)
Polycythemia
Hepatitis (oral tabs only)
What can cause diabetes insipidus?
Familial – isolated or DIDMOAD
Acquired (idiopathic, RTA, surgery, skull #)
Rare (tumour, Sarcoid, meningitis, ext radiation)
What are the symptoms of DI?
Polyuria
Polydipsia
Signs of dehydration (sometimes)
Blurred vision (rarely)
What are the symptoms of Cushing’s disease?
Weight gain (central) HTN Alopecia Easily bruised Back pain Conjunctival oedema (chemosis) proximal myopathy thin skin striae facial plethora acne amenorrhoea altered psyche
What causes primary Cushing’s disease?
Adrenal adenoma
Pituitary adenoma
Ectopic ACTH (usually carcinoma - lung)
Name 3 causes of secondary Cushing’s disease?
Steroid meds
Alcohol – pseudocushing’s
Depression
What screening tests are used for Cushing’s disease?
Dexamethasone 1mg overnight
24hr urinary free cortisol
Morning & midnight cortisol
What test is used to provide a definitve diagnosis of Cushing’s disease?
Low dose dexamethasone
When Cushing’s disease is caused by a pituitary adenoma, is it likely to be a micro or macro adenoma?
microadenoma
When Acromegaly is caused by a pituitary adenoma, is it likely to be a micro or macro adenoma?
Macroadenoma
A pituitary adenoma = 1cm is known as what?
Mesoadenoma
What test is used to differentiate between the causes of Cushing’s disease?
Short synacthen test
What are the 4 endocrine causes of HTN?
Phaechromocytoma
Cushing’s
Conn’s syndrome
Acromegaly
Chronic suppression of pituitary ACTH production and adrenal atrophy leads to what?
unable to respond to stress (illness/surgery)
need extra steroid when ill
CANNOT stop steroid suddenly - gradual
What treatment can be used for the different types of Cushing’s disease?
Pituitary: hypophysectomy and external radiotherapy if recurrence
Adrenal: adrenalectomy
Ectopic: remove source or bilateral adrenalectomy
Metyrapone – if other Tx fails or while waiting for radio to work
