Thyroid and Parathyroid Pathology Flashcards
What is a ‘goitre’?
Swollen, enlarged thyroid gland
What is euthyroid?
Normal thyroid gland function
What people get a diffuse goitre thyroid?
Yonger people
What people get a multinodular goitre thyroid?
Older people
What can cause hypothyroidism?
Iodine deficiency - endemic (seaweed may cause hyperthyroidism)
Goitrogens
- Drugs - Lithium, amiodarone
- Diet - cabbage, turnips
What is the most common drug that can cause goitre?
Lithium
What can the pathogenesis of hypothyroidism be?
- Reactive
- Iodine block
- Genetic
How do benign masses and malignancies differ in the thyroid on inspection?
- Benign masses are usually movable, soft and non-tender
- Malignancy is associated with a hard nodule, fixation to surrounding tissue, and regional lymphadenopathy
What are the signs and symptoms of hyperthyroidism?
- Nervousness
- Heat intolerance
- Diarrohea
- MUscle weakness
- Loss of weight and apetite
What are the signs and symptoms of hypothyroidism?
- Cold intolerancce
- Constipation
- Fatigue
- Weight gain
What are signs / symptoms of local nerve involvement in a thyroid pathology?
- Dysphagia and hoarsness
- Could be a sign of malignancy
What do the follicles look like on histology in multinodular goitre?
Different sizes
How is a thyroid pathology diagnosed?
- Thyroid function test
- Antithyroid antibodies
- Complete blood count
- Fine needle aspirate
Imaging - Ultrasnogtophy
- Radioiodine scintigraphy
- Chest radiography
- CT, MRI
What may an elevated thyroid-stimulating hormone (TSH) indicate?
Thyroiditis
What may a very low TSH level indicate?
An autonomous or hyperfunctioning nodule
What are antithyroid antibodies helpful in?
Diagnosing chronic lymphocytic thyroiditis (Hashimoto thyroiditis)
What can a solitary thyroid nodule be?
- Abcess
- Thyroid pathology
What are the diseases of the thyroid?
- Trauma
- Toxicity (lithium)
- Goitre, solitary nodule, neoplasms
- Chronic inflammation - immune or not
- Acute thyroiditis, abscess
- Metabolic, genetic
What is the classic sign of an overactive thyroid?
Exophthalmos (buldging of the eye) (build up of fatty tissue pushing eyeball forward)
What is the most common cause hyperthyroidism?
- Graves (may present as diffuse toxic goitre)
What can cause hyperthyroidism?
- Graves
- Functional goitre
- Toxic adenoma
What can cause hypothyroidism?
- Congenital
- Autoimmune (commonest in adults)
What happens in hypothyroidism?
- Defective TH production
- Loss of parenchyma
- Deficient TSH
What is graves disease caused by?
- IgG against TSH receptor on thyrocytes
- Antibody is not compliment fixing IgG class 2 or 4 not 1 or 3
- Mimics TSH
What gender is more likely to get Graves disease?
female - 10:1 over males
What may Graves disease present as?
Diffuse toxic goitre
What genes may cause graves?
Strong family history HLA DR3 and CTLA-4
What group of people are most likely to be affected by Hashimoto thyroiditis?
Female 30-50 (again ~ 10:1 ratio against males)
Describe the pathogenesis of Hashimoto thyroiditis?
- Autoreactive CD8 T lymphocytes
- Autoreactive antibodies: thyroid microsomal in almost all 95% thyroglobulin in 2/3s, minority have blocking TSH receptor antibodies
- Can cause hyper or hypothyroidism (primarily hypothyroidism)
What may the thyroid gland look and feel like in hashimoto thyroiditis?
- Multinodular
- Shrunken
- Hard
- Fibrotic
- Scarring
What can cause hashimoto thyroiditis?
- FH (like many autoimmune diseases)
- Increased iodine intake
- Viral infection
What is a long term risk of hashimoto thyroiditis?
Lymphoma
What are benign neoplasms of the thyroid?
Follicular adenoma
What are malignant neoplasms of the thyroid?
- Primary about 1% of cancers; papillary, follicular, anaplastic, medullary (parafollicular cells), lymphoma
- Metastic: Lymphoma
Who is likely to be affected by follicular adenomas?
Females: 30 - 50 years
How large are the follicular adenomas usually?
1 - 3 cm at presentation (small, incapsulated, not usually invasive)
What is the most common cause of thyroidd cancer?
Papillary carcinoma (80%)
What group does papillary carcinoma affect?
Females (3:1) 20 - 50 years
What are the causes of papillary carcinomas?
- Radiation (Chernobyl)
- Family History
- Unknown
What genes can cause papillary carcinoma?
- Rearrangement of RET oncogene in most
- B-RAF mutation in half - associated with increased risk of LN mets
What does papillary carcinoma look like upon histology?
Instead of having pattern of regular follicles follicle linings become complex and branched forming papillary
- Gobs of calcium also present
What percentage of thyroid cancers are follicular carcinomas?
20%
What group does follicular carcinomas affect?
- Females:Males (3:1)
- Older than 40
What genes can cause follicular carcinoma?
- RAS oncogene
- PAX8/PPARG rearrangement
How can folllicular carcinoma spread?
- Minimally invasive versus invasive
- Blood spread may present in bone marrow
What is anaplastic carcinom?
- Less common
- p53 mutation common
- May have had previous thyroid neoplasia
- Half have had chronic goitre
- Female:Male 4:1
What cells are attacked in medullary carcinoma?
Parafollicular cells (tumors can produce amyloid instead of calcitonin)
What genes can be involved in medullary carcinoma?
RET proto-oncogene activation (20% familial, in youngeer patients)
What are the causes of primary hyperparathyroidism?
- Adenoma (4/5s)
- Hyperplasia (some familial)
- Parathyroid carcinoma (less than 1%)
What are the causes of secondary hyperparathyroidism?
- Caused by low calcium (e.g chronic renal failure and vitamin D deficiency)
What are the causes of tertiary hyperparathyroidism?
Raised caclcium in secondary
What are the effects of hypercalcaemia?
- Emotional disorders
- Muscle atrophy
- Parathyroid adenoma or hyperplasia
- Osteitis fibrosa cystica
- Peptic ulcer
- Pancreatitis
- Kidney stone
- Nephrocalcinosis
- Arrhythmia
- Calcification of blood vessels
What cancer can cause hyperparathyroidism?
Small cell lung cancer
What is multiple endocrine neoplasia?
- Genetically inherited (MEN1 and MEN2)
- Associated with tumours in the endocrine organs (specifically parathyroid and neuroendocrine cell and parafollicular calcitonin producing cell in thyroid)
