Lecture 16: Pathology of Endocrine Diseases Flashcards
What is the function of the thyroid gland?
- synthesis, storage and release of thyroxine (T4) and triiodothyronine (T3) > REGULATES BASAL METABOLIC RATE (BMR).
- secretion of calcitonin > REGULATES CALCIUM HOMEOSTASIS.
thyroid epithelial cells are arranged in follicles with colloid, what does colloid contain?
thyroglobulin
what is the function of thyroid epithelial cells?
- thyroglobulin synthesis, iodination, resorption and release of T3 & T4.
what is the most common cause of multi-nodular goitre?
explain the mechanism
Iodine deficiency, goitrogens > impaired synthesis of T3, T4 > increased TSH > hypertrophy and hyperplasia of thyroid epithelium
investigation of thyroid nodule
TFTs
US
FNA - cytology
thyroid carcinoma risk factors
- family history
- chronic inflammatory exposure
- radiation exposure
- obesity
features of a thyroid follicular adenoma
- benign neoplasm
- most non-functioning
- circumscribed, encapsulated tumour
- histology often small microfollicles
features of a follicular carcinoma of the thyroid gland
- rare, usually solitary
- malignant cells breach capsule
- mets - blood, bone
- RAS mutation or PAX8/PPARG translocation
features of thyroid papillary carcinoma
- usually < 50 years old
- BRAF mutation or RET/PTC gene arrangement
- associated with exposure to ionising radiation
- spreads via lymphatics but excellent prognosis: 85% survival 10 years (esp. < 55 years old).
features of a thyroid medullary carcinoma
- malignant tumour of C-cells
- produces calcitonin (+/- other polypeptides)
- 70% sporadic
- 30% MEN 2A,2B, familial FMTC: mutations in RET proto-oncogene > prophylactic thyroidectomy advised.
what is the treatment for a thyroid carcinoma?
go through each type
- follicular and papillary usually treated by surgery and radioactive iodine
- medullary often treated by surgery and external radiotherapy
- anaplastic: often no viable surgical option
- replacement hormones usually required following surgery
what is the most common cause of pituitary hyperfunction?
pituitary adenoma
effects of pituitary adenoma
think about each hormone secreted
If functioning adenoma > hormone excess:
- Prolactinoma (20-30%): galactorrhoea, menstrual disorders
- GH secreting: acromegaly, gigantism
- ACTH secreting: Cushing’s disease
Non-functioning:
- 25-30% of detected tumours
- immunohistochemical and/or ultrastructural demonstration of hormone production only (mostly prolactin)
effects of large pituitary mass
- radiographic abnormalities
- visual field abnormalities
- elevated ICP
- compression damage - hypopituitarism
causes of pituitary hypofunction (75% needs to be lost)
- compression by tumours: craniopharyngioma, metastatic
- trauma
- infection (rare): TB, sarcoidosis
- post-partum ischaemic necrosis: Sheehan’s syndrome
list 3 syndromes causing adrenal cortical hyperfunction
- hypercortisolism: Cushing’s syndrome
- Hyperaldosteronism: Conn’s syndrome
- adrenogenital syndromes
give a cause of acute adrenal insufficiency
- meningococcal septicaemia: Waterhouse Friderichsen
list causes of chronic adrenal insufficiency
1 year - Addison’s disease:
- autoimmune
- infections: TB, fungus HIV-related infections
- replacement: metastatic carcinoma and amyloidosis
- atrophy: prolonged steroid therapy
- congenital hypoplasia
2 years - Pituitary failure
describe multiple endocrine neoplasia
- genetically inherited diseases resulting in hyperplasia and benign and malignant tumours of the endocrine system.
- younger age, multifocal
- several distinct syndromes
features of MEN 1 (Wermer syndrome)
- MEN1 tumour suppressor gene mutation - defect in menin protein involved in regulating cell growth.
- parathyroid hyperplasia and adenomas.
- pancreatic and duodenal endocrine tumours (hypoglycaemia and ulcers).
- pituitary adenoma (prolactinoma).
features of MEN 2 syndrome
include MEN2A and MEN2B
- RET proto-oncogene mutations.
- medullary carcinoma of thyroid
- phaeochromocytoma
MEN 2A (Sipple syndrome):
+ parathyroid hyperplasia
MEN 2B:
+ neuromas of skin & mucous membrane, skeletal abnormalities
+ younger patients, aggressive
what neoplasia/hyperplasia are present in MEN 1?
- pituitary adenoma
- parathyroid hyperplasia
- pancreatic tumours
what neoplasia/hyperplasia are present in MEN 2A?
- parathyroid hyperplasia
- medullary thyroid carcinoma
- pheochromocytoma
what neoplasia/hyperplasia are present in MEN 2B?
- mucosal neuromas
- marfanoid body habitus
- medullary thyroid carcinoma
- pheochromocytoma
