Histo: Endocrine disease Pt.2 Flashcards
Describe the effect of TSH receptor-stimulating antibodies.
They stimulate thyroid hormone release and increase proliferation of the thyroid epithelium.
What is the triad of Grave’s?
- Hyperthyroidism
- Infiltrative ophthalmopathy - exopthalmos (40%)
- Infiltrative dermopathy - pretibial myoedema (minority)
Also associated with other autoimmune diseases e.g. SLE, T1DM, pernicious anaemia, Addison’s
List some primary and secondary causes of hypothyroidism.
Primary
- Post-ablative
- Autoimmune (Hashimoto’s)
- Iodine deficiency
- Congenital biosynthetic defect
Secondary
- Pituitary or hypothalamic failure (uncommon)
Describe the presentation of Hashimoto’s thyroiditis.
- Painless enlargement of the thyroid gland
- Symptoms of hypothyroidism.
Describe the histology of Hashimoto’s thyroiditis.
- There are lots of lymphoid cells with germinal centres
- The epithelial cells become large with lots of eosinophilic cytoplasm (Hurthle cells)
Types of thyroid neoplasms:
- Adenoma - benign tumours of follicular epithelium
- Carcinoma - uncommon (accounts for < 1% of solitary thyroid nodules)
List some features of a thyroid lump that would be suggestive of neoplasia.
- Solitary rather than multiple
- Solid rather than cystic
- Younger patients
- Male more than female
- Less likely to take up radioiodine (cold nodules)
How thyroid neoplasms diagnosed?
- Fine needle aspiration cytology
- Histology
List some features of adenomas of the thyroid gland.
- Usually solitary
- Well circumscribed
- Well-formed capsule
- Small proportion will be functional
List the four types of thyroid cancer in order of decreasing prevalence.
- Papillary (80%)
- Follicular (15%)
- Medullary (5%)
- Anaplastic (< 5%)
What are some risk factors for thyroid cancer?
- Genetic factors (e.g. MEN)
- Ionisation radiation (mainly papillary)
What is the histological features of papillary thyroid cancer?
Nuclear features
- Optically clear nuclei (Orphan Annie Eye)
- Intranuclear inclusions
There may also be psammoma bodies (round calcifications)
What are some clinical features of papillary thyroid cancer?
- Non-functional
- Presents with painless neck lump
- Can metastasize
- 90% 10 year survival
Where does papillary thyroid cancer tend to metastasise to?
Cervical lymph nodes
Where does follicular thyroid cancer tend to metastasise?
Lungs, bone and liver (via the bloodstream)
Which cells are medullary thyroid cancers derived from?
Parafollicular C cells
NOTE: 80% are sporadic (50-60 yrs), 20% are familial (MEN - younger patients)
What tends to happen to the calcitonin produced by tumour cells in medullary thyroid cancer?
- It is broken down and deposited as amyloid within the thyroid
What is the most aggressive thyroid cancer?
Anaplastic
- Occurs in elderly
- Metastases common
- Usually death in < 1 year
What are the parathyroid glands derived from?
Developing pharyngeal pouches
What controls PTH secretion?
Serum calcium concentration (sensed by CaSR)
List the actions of PTH.
- Activates osteoclasts
- Increased renal absorption of calcium
- Increases activation of vitamin D
- Increases urinary phosphate exretion
- Increases intestinal calcium absorption
What is hyperparathyroidism usually caused by?
- 80% solitay adenoma
- 20% due to hyperplasia of all four glands (sporadic or part of MEN1)
- < 1% carcinoma
Describe the histological appearance of a parathyroid adenoma.
Very cellular tissue with no fat (whereas the normal parathyroid gland is quite fatty)
What bone change is seen in hyperparathyroidism?
Osteitis fibrosa cystica - caused by bone resorption with thinning of the cortex
What are the effects of primary hyperparathyroidism?
- Bone - increased resorption (OFC)
- Kidneys - stones and obstructive nephropathy
- GI - constipation, pancreatitis, gallstones
- CNS - depression, lethary, seizures
- Muscular weakness
- Polyuria and polydipsia
“Painful bones, renal stones, abdominal groans, psychic moans”
