Pathology Flashcards
What embryological structure forms the anterior pituitary?
Rathke’s Pouch
Differentiate the trophic and non-trophic hormones secreted by the anterior pituitary
Trophic: TSH, ACTH, FSH, LH
Non-trophic: GH and Prolactin
What type of cells make up the posterior pituitary gland?
modified glial cells and axonal processes
What hormones does the posterior pituitary gland secrete?
Secretes ADH (vasopressin) and oxytocin
The hormone secreting cells in the anterior pituitary are either Acidophils or Basophils. Classify them into both groups.
ACIDOPHILS:
Somatotrophs – secrete GH
Mammotrophs – secrete PROLACTIN
BASOPHILS:
Corticotrophs – secrete ACTH
Thyrotrophs – secrete TSH
Gonadotrophs – secrete FSH / LH
What name is given to a cell which does not absorb acidic nor basic dye?
Chromophobe
What pathologies of the anterior pituitary usually result in HYPERfunction?
Adenoma
Carcinoma
What conditions of the anterior pituitary often cause HYPOfunction?
- Surgery/radiation
- Sudden Haemorrhage into gland
- Ischaemic necrosis
- Sheehan Syndrome (post-partum necrosis)
- Tumours extending into sella turnica
- Inflammatory conditions (e.g. Sarcoidosis)
How does the posterior pituitary cause Diabetes insipidus?
- Lack of ADH secretion
- Can lead to life threatening dehydration
What condition is characterised by ectopic secretion of ADH by tumours?
Syndrome of Inappropriate ADH secretion (SIADH)
Pituitary adenomas are always sporadic. TRUE/FALSE?
FALSE
can also be associated with MEN1 gene mutation
Pituitary adenomas can secrete more than one hormone. TRUE/FALSE?
TRUE
although some tumours can be non-functioning also
What symptoms can large adenomas cause locally?
- Atrophy of surrounding normal tissue due to pressure
- Visual field defects
- Infarction leading to panhypopituitarism
What is the most common FUNCTIONAL tumour found in the anterior pituitary?
Prolactinoma
How does a prolactinoma usually present?
Infertility
lack of libido
amenorrhea
A tumour secreting GH causes an increase in what peripheral hormone? And what can this cause?
- Insulin Like Growth Factors (IGF)
- Stimulates growth of bone, cartilage and CT
- causes Gigantism (if bones yet to fuse) or acromegaly
What type of tumours usually secrete ACTH?
Microadenoma
OR Bilateral adrenocortical hyperplasia
What hormones do pituitary carcinomas usually secrete?
Prolactin or ACTH
Pituitary carcinomas tend to metastasise early. TRUE/FALSE?
FALSE
metastasise LATE after multiple recurrences
Craniopharyngiomas are slow growing. TRUE/FALSE
TRUE
Also often cystic and may calcify
Where do most Craniopharyngiomas arise?
Most are suprasellar
What symptoms are usually present in Craniopharyngiomas?
- Headaches and visual disturbances
- Children may have growth retardation
Craniopharyngiomas have a good prognosis. TRUE/FALSE?
TRUE (If <5cm)
Risk of SCC after radiation
What is “Nephrogenic” Diabetes Insipidus?
Renal resistance to the effects of ADH
How much does one adrenal gland roughly weigh?
4-5 grams
What are the two distinct anatomical regions of the adrenal gland?
Cortex and Medulla
What conditions can cause hyperfunction in the adrenal cortex?
Hyperplasia
Adenoma
Carcinoma
Adrenal cortex hypofunction can be acute or chronic. What are the causes of each?
Acute
- Waterhouse-Friderichsen (septic infection)
Chronic
- Addison’s disease
Congential Adrenocortical Hyperplasia is Autosomal Dominant. TRUE/FALSE?
FALSE
Autosomal Recessive
Describe the pathogenesis of Congential Adrenocortical Hyperplasia
Enzyme deficiency
=> cant make aldosterone/ cortisol
=> all shunted to androgen production
Reduced cortisol stimulates ACTH release and cortical hyperplasia
What does the androgen production in CAH lead to?
Virilisation
Precocious Puberty
Describe the pathogenesis of acquired Adrenocortical Hyperplasia
Endogenous ACTH production from:
- Pituitary adenoma
OR Ectopic ACTH from:
- Paraneoplastic syndrome (small cell lung carcinoma)
Causes Bilateral adrenal enlargement to meet Cortisol demands from all excess ACTH
Adrenocortical tumours are usually an incidental finding in adults. TRUE/FALSE
TRUE
Describe the appearance of an adrenocortical adenoma
- Well circumscribed
- Usually small (2 to 3cm)
- Yellow/brown surface (lipid)
- Composed of cells resembling adrenocortical cells
- Can be functional, but unlikely
Where do adrenocortical carcinomas usually spread to?
Local invasion – retroperitoneum, kidney
Metastasis – vascular (liver, lung and bone)
Peritoneum and pleura
Regional lymph nodes
What is the 5 year survival for adrenocortical carcinomas?
20-35%
50% are dead within the first 2 years
Adrenocortical Adenomas and Carcinomas look very similar. What can help to differentiate between them?
- Large size (often >20cm)
- Haemorrhage and necrosis
- Frequent mitoses, atypical mitoses
- Lack of clear cells
- Capsular or vascular invasion
What syndrome is related to an oversecretion of aldosterone from the adrenal cortex?
Conn’s
= Primary Aldosteronism
What are the most common causes of Conn’s syndrome?
60% = diffuse or nodular hyperplasia of both adrenal glands 35% = Adenoma RARE = carcinoma
What hormone is secreted to excess in Cushing’s syndrome?
Cortisol
What are the most common causes of Cushing’s?
Exogenous Cause: Iatrogenic (steroid therapy)
Endogenous Cause:
- ACTH secreting pituitary adenoma
- Ectopic ACTH (e.g. Small cell lung cancer)
- Adrenal adenoma/carcinoma
- Adrenal gland atrophy => no lesions
What can cause ACUTE adrenocortical insufficiency?
- Rapid withdrawal of steroid treatment
- increasing dose of steroid treatment
- Acute adrenal Crisis if pts have chronic disease
- Massive adrenal haemorrhage
- Newborn
- Anticoagulant treatment
- Septiceamic infection – Waterhouse Friderichsen
What are the most common causes of Addison’s disease?
- Autoimmune adrenalitis
- Infections (TB/fungal/HIV)
- Metastatic malignancy (Lung, breast)
What are the more unusual causes of Addison’s disease?
Amyloid
Sarcoidosis
Haemochromatosis
How much of the gland is already destroyed by the time Addison’s disease presents?
90%
What vague symptom differentiates Addison’s disease from hypopituitarism?
Raised Pigmentation
=> patients often seem tanned (or even orange)
Biochemically, how do patients with Addison’s Disease present?
Hyperkalaemia (High K+)
hyponatraemia (Low Na+)
Volume depletion => hypotension (Low BP)
Hypoglycaemic
How do patients in Acute Addison’s crisis present?
- Vomiting
- abdominal pain
- hypotension
- shock and death
What innervates the Adrenal medulla?
Pre-synaptic fibres from sympathetic nervous system
What cells are found in the adrenal medulla and what do they secrete?
Neuroendocrine (chromaffin) cells
=> secrete catecholamines
What two types of tumour are most commonly found in the adrenal medulla?
Phaechromocytoma
Neurblastoma
What do Phaechromocytomas secrete?
Secrete catecholamines
Phaechromocytomas can rarely cause secondary Hypertension. TRUE/FALSE?
TRUE
What complications can arise from the secondary hypertension of Phaechromocytoma?
Cardiac failure
infarction
arrhythmias
How should a Phaechromocytoma be investigated for in the lab?
Detection of urinary excretion of catecholamines and metabolites
Why is Phaechromocytoma known as the 10% tumour?
10% are extra-adrenal 10% are bilateral 10% are malignant 10% are NOT associated with hypertension 25% are familial
How do Phaechromocytomas usually look?
Yellow, red/brown due to haemorrhagic and necrotic nature
Tumour turns dark brown due to oxidation of catecholamines in tumour cells
Where do Phaechromocytomas metastasise to?
skeletal metastasis
regional lymph nodes
liver
lung
What subtypes of Multiple Endocrine Neoplasia does a Phaechromocytoma usually present in?
MEN2a
MEN2b
What are the 3 zones found in the adrenal cortex?
Zona Glomerulosa
Zona Fasciculata
Zona Reticularis
What hormones are secreted by the Zona Glomerulosa?
Mineralocorticoids
=> Aldosterone
What hormones are secreted by the Zona Fasciculata?
Glucocorticoids
=> Cortisol
What hormones are secreted by the Zona Reticularis?
Sex Steroids + Glucocorticoids
