Pathology of the Endocrine System Flashcards
How is balance of endocrine systems maintained?
By feedback inhibition
How are endocrine organs linked?
By feedback axis
3 things that can go wrong in endocrine pathology
Hyperfunction
Hypofunction
Effect of a mass lesion
Definition of hyperplasia
Increased number and secretory activity of cells
Definition of atrophy
Diminution of cells due to lack of stimulation
How would tissue damage of an endocrine organ be caused?
Inflammation Autoimmune disease Compression Trauma Infarction
Two types of neoplasia of endocrine organs
Adenoma (benign)
Carcinoma (malignant)
Types of adenoma
Functioning
Non functioning
Types of carcinoma
Primary
Metastatic
What does the thyroid gland produce?
Thyroxine T4
Triiodothyronine T3
Calcitonin
What secretes calcitonin?
C cells
Causes of hyperthyroidism
Graves disease 70%
Toxic multinodular goitre 20%
Toxic adenoma
Who gets graves disease?
F > M
Peak 20-40 years
Is there a genetic predisposition to get graves disease?
Yes
Pathology of graves disease
Autoimmune production of anti TSH receptor antibodies
Stimulate activity, growth and inhibit TSH binding
Histology of graves disease
Increased cell activity
Increased cell numbers
Causes of hypothyroidism
Hashimotos thyroiditis
Iatrogenic - surgery, drugs
Iodine deficiency
Congenital hypothyroidism
Who gets Hashimotos thyroiditis?
F > M
45 - 65 y/o
Pathology of hashimotos thyroiditis
Autoimmune destruction of thyroid epithelial cells
Cytotoxic T cells, cytokine and antibody mediated destruction
Circulating antibodies to thyroglobulin and thyroid peroxidase
Size of the thyroid in hashimotos disease
Originally - the gland gets bigger even though it is being destroyed, as it is trying to compensate
This does result in destruction however and fails and therefore the gland then gets smaller
Histology of hashimotos
Hurthle cell change
- swollen
Intense infiltrate of lymphocytes and plasma cells
What is goitre?
An enlarged thyroid
Pathology of multinodular goitre
Iodine deifiency/goitrogens/other causes
Impaired synthesis of T3,T4
Increased TSH
Hypertrophy and hyperplasia of epithelium
What may develop in multinodular goitre?
Autonomous “toxic nodule”
Pathology of multinodular goitre
Area of the thyroid that is no longer responding to TSH stimulation and reduction
Pumps out thyroxin regardless
What may the dominant nodule in a multinodular goitre be?
Cyst
Follicular adenoma
Carcinoma
Investigations of a thyroid nodule
TFTs
USS
FNA
What do parathyroid glands produce?
PTH
How many parathyroid glands are there?
4
What does PTH do?
Regulates plasma Ca2+
Presentation of primary hyperparathyroidism
Usually asymptomatic hypercalcaemia
Causes of primary hyperparathyroidism
Sporadic or familial (MEN-1)
- adenoma 85-95%
- hyperplasia 5-10%
- carcinoma - rare
Causes of secondary hyperparathyroidism
Physiological response to a decreased Ca2+ renal failure
Functions of the hypothalamus
Maintains homeostasis
Governs emotional behaviour
Links nervous system to endocrine system via the pituitary gland
Where is the pituitary gland found in?
Sella turcica
How is the pituitary gland connected to the hypothalamus?
Via the pituitary stalk
Another name for the anterior pituitary gland
Adenohypophysis
Where does the anterior pituitary get its blood supply from?
Hypothalamus
What does the anterior pituitary secrete?
ACTH TSH GH Prolactin FSH/LH
Another name for the posterior pituitary
Neurohypophysis
What does the posterior pituitary secrete?
ADH
Oxytocin
3 major cell types of the anterior pituitary
Pink acidophils
Dark purple basophils
Pale chromophobes
What do the pink acidophils secrete?
GH
PRL
What do the dark purple basophils secrete?
ACTH
TSH
FSH
LH
Most common cause of pituitary hyperfunction
Pituitary adenoma
What age do people usually get pituitary adenomas?
35-60 y/o
If a functioning pituitary adenoma was producing prolactin, what would this lead to and how common is this?
Prolactinoma
20-30%
If a functioning pituitary adenoma was secreting GH, what would this lead to?
Gigantism
Acromegaly
What would a functioning pituitary adenoma producing ACTH lead to?
Cushing’s disease
How common is a pituitary carcinoma?
very rare
Effects of a large pituitary adenoma giving a mass pressure effect
Radiographic abnormalities
Visual field abnormalities
Elevated Intracranial pressure
Compression damage - hypopituitary
How much of the pituitary needs to be lost to give it hypofunction?
75%
Causes of pituitary hypofunction
Compression by tumours - craniopharyngioma - metastatic Trauma Infection (rare) - TB - sarcoidosis
Zones of the adrenal cortex
Zona glomerulosa
Zona fasiculata
Zona reticularis
What does the zona glomerulosa secrete?
Mineralocorticoids
What does the zona fasiculata secrete?
Glucocorticoids - cortisol
What does the zona reticularis secrete?
Sex steroids
Oestrogen
Androgens
What cells are found in the adrenal medulla?
Neuroendocrine (chromaffin) cells
What does the adrenal medulla produce?
Adrenaline/noradrenaline
What syndrome is related to hypercortisolsim?
Cushing’s syndrome
What syndrome is related to hyperaldosteronism?
Conn’s syndrome
Causes of cushing’s syndrome
Iatrogenic steroids Pituitary adenoma (cushings disease) - 70% Ectopic ACTH Functioning adrenal adenoma - 10% Independent adrenal adeoma Dependent pituitary adenoma
Pathology of conns syndrome
Hyperalsoteronism
Bilateral idiopathic hyperplasia
Cause of conns syndrome
Functioning adrenal adenoma
Cause of secondary hyperaldosteronim
Physiological due to decreased renal perfusion and increased renin-angiotensin
Examples of adrenogenital syndromes
Functioning adrenal tumour
Pituitary tumour cushings disease
Congenital adrenal hyperplasia - steroid enzyme deficiency
Causes of adrenal insufficiency
Meningococcal septicaemia
Addisons disease
Pituitary failure
Causes of addisons disease
Autoimmune
Infections; TB, Fungus HIV-related infections
Replacement; metastatic carcinoma amyloidosis
Atrophy; prolonged steroid therapy
Congenital hypoplasia
What are adrenocortical tumours?
Primary tumours of the adrenal cortex which are quite rare and are often benign
Types of adrenocortical tumours
Adenoma
Carcinoma
What tumour is found in the adrenal medulla?
Phaechromaocytoma
Main feature of phaechromocytoma
Hypertension
What % of phaechromocytoma is inherited?
up to 30%
What are multiple endocrine neoplasias?
Hyperplasia/neoplasms of endocrine organs - younger age, multifocal. Inherited disorders with an underlying genetic mutation
Distinct syndromes associated with endocrine neoplasms
MEN 1 (Wermer syndrome) MEN 2 (A, B and C)
What does MEN 1 have a defect in?
Menin protein involved in regulating cell growth
What endocrine neoplasias does MEN 1 result in?
Parathyroid hyperplasia and adenomas Pancreatic and duodenal endocrine tumours (hypoglycaemia and ulcers) Pituitary adenomas (prolactinoma)
What do MEN 2 result in with endocrine neoplasias?
Medullary carcinoma of the thyroid
Phaeochromocytoma
In addition to the MEN 2 conditions, what else does MEN2A have?
Parathyroid hyperplasia
In addition to the MEN2 conditions, what else does MEN 2 B have?
Neuromas of skin and mucous membranes
Skeletal abnormalities
Younger patients and aggressive
Treatment of myxoedema coma
Hydrocortisone and levothyroxine
Hormones that decrease during the stress response
Insulin
Testosterone
Oestrogen
