Pathology of the thyroid and parathyroid glands Flashcards
What are different Thyroid clinical presentation you may see ?
- Goitre (thyroid enlargement)
- Lump (Focal)
- Hyperthyroidism
- Hypothyroidism
What are the different Goitres you can get and what causes them?
Euthyroid (normal thyroid function);
- Diffuse (smooth and uniformly enlarged) - younger people
- Multinodular (more lumpy) - older
Hypothyroid;
- Iodine deficiency - endemic, with little iodine in water, why we add into diet (versus seaweed causing hyperthyroid and blocks iodine transport)
Goitrogens;
- Drugs - LITHIUM (used in psych), amidarone (used in cardiac)
- Diet - cabbage, turnips
Pathogenesis (questions you’re asking yourself);
- Is it reactive ?
- Iodine block ?
- Genetic?
What questions would you ask yourself when seeing patients with a Goiter or Solitary thyroid nodule?
- Who gets it?
- When ?
- How is the underlying cause diagnosed?
- Why does it happen?
- How does it happen?
- What does it look like ?
- What are its effects ?
- How is it treated ?
What are the Signs and Symptoms of Solitary thyroid nodule?
Is it?
- Benign - masses are usually moveable, soft and non tender (as they’re non-invasive).
- Malignancy - is associated with a hard nodule, fixation to surrounding tissue and regional lymphadenopathy
Most patients are asymptomatic but exhibit signs and symptoms of altered levels of thyroid hormone;
Hyperthyroidism - Nervousness, heat intolerance, diarrhoea, muscle weakness and loss of weight and appetite
Hypothyroidism - Cold intolerance, constipaton, fatigue, and weight gain, which in children is primarily caused by the accumulation of myxedematous fluid
Looks for signs and symptoms of local nerve involvement (recurrent laryngeal), dysphagia or hoarseness triggers rapid investigation because it may indicate a carcinoma with invasion
On biopsy looks benign as they look regular, no enlarged nucelli - but thyroid is special even malignant looks like normal
- Point is its challenging need to use other things for diagnosis like thyroid function
What is a Solitary thyroid nodule ?
Solitary thyroid nodule;
- When it is large enough to see easily, it’s called a goiter. A thyroid nodule is a lump or enlarged area in the thyroid gland. A nodule may simply be swollen tissue, an overgrowth of normal thyroid tissue, or a collection of fluid called a cyst. Most thyroid nodules in children are not caused by cancer.
How would be diagnose Solitary thyroid nodule?
Diagnosis:
- Thyroid function tests - elevated thyroid-stimulating hormone (TSH) level may indicate thyroiditis; a very low TSH level indicates an autonomous or hyper functioning nodule
- Antithyroid antibodies - Helpful in diagnosing chronic lymphocytic thyroiditis (Hashimoto thyroiditis)
- Full blood count - abscess
- Value and limitations of fine needle aspiration cytology
Imaging studies;
- Ultrasonography - to determine whether nodule is cystic, solid, or mixed
- Radioiodine scintigraphy - to determine whether the nodule is cold, warm or hot
- Chest radiography - If malignancy is suspected given the high incidence of early metastases to lungs
- Computed tomography (CT) scanning and magnetic resonance imaging (MRI)
What are the different classes of diseases of the thyroid?
- Trauma and toxicity
- Goitre, solitary nodule, neoplasms
- Chronic inflammation - immune or not
- Acute thyroiditis, abscess
- Metabolic, genetic
What are the common features of Hyperthyroidism ?
- Commonest is Graves - may present as diffuse toxic goitre
- Functional goitre
- Toxic adenoma - produces more thyroxine, hence hyperthyroidism
Because you have too much Thyroxine - Makes things go faster
Might see;
- Muscle wasting
- Fine hair
- Exophthalmos
- Goiter
- Sweating
- Tachycardia, high output failure
- Weight loss
- Oligomenorrhoea
- Tremor
What are the common features of Hypothyroidism ?
- Congenital
Autoimmune;
- Defective Thyroid Hormone production
- loss of parenchyma
- Deficient TSH
Might see;
- Muscle weakness
- Coarse, brittle hair
- Loss of lateral eyebrows
- “Myxedema” madness
- Periorbital oedema and puffy face
- Pallor
- Large tongue
- Hoarseness
- “Myxedema” heart (cardiomegaly)
- Constipation
- Menorrhagia
- Peripheral oedema
Myxodema - swelling of the skin and underlying tissues giving a waxy consistency, typical of patients with underactive thyroid glands.
What are the causes of Graves?
Most common autoimmune Hyperthyroidism;
- Autoimmune
- under 40 years old
- 10 Female : 1 Male
- Immune - IgG against TSH receptor on thymocytes (activates receptor)
- Strong family history HLA, DR3 and CTLA-4
Thyroid thinks its being stimulated by TSH but tis not its antibody, but no feedback so keep producing more and more
Histology - Bigger circles, more cells, pink stuff colloid with thyroxine being produced and exported, artefactual shrinkage because colloid removed and TSH exported
What is this histological image showing?
Graves disease - Bigger circles, more cells, pink stuff colloid with thyroxine being produced and exported, artefactual shrinkage because colloid removed and TSH exported
What are the causes of Hashimoto’s ?
Most common autoimmune Hypothyroidism;
- Autoimmune
- Females 30 - 50 years old (genetic component)
- Auto reactive CD8 T lymphocytes (cytotoxic T cells)
- Autoreactive antibodies: thyroid microsomal in almost all 95% thyroglobulin in 2/3rds, minority have BLOCKING TSH receptor antibodies
- Family history strong and other autoimmune diseases
Other casual risks? Increased iodine intake, viral infection
Damages thyroid causing colloid leaks out and thyroid levels go up and then over the with more tissue damage get a shrunken, nodular thyroid, with lots of lymphocytes (blue) and small, innocuous and quiet thyroid cells
More likely to develop a Lymphoma - as chronic drive of inflammatory response
What is this histological image showing?
Hashimoto’s - Damages thyroid causing colloid leaks out and thyroid levels go up and then over the with more tissue damage get a shrunken, nodular thyroid, with lots of lymphocytes (blue) and small, innocuous and quiet thyroid cells
What are the types of Neoplasms you can get in the thyroid?
- Benign: Follicular Adenoma (most common!)
Malignant;
- Primary: About 1% of cancers: Papillary, follicular, anapllastic, medullary, lymphoma
- Metastatic: Lymphoma
What are the features of Follicular Adenoma?
Follicular Adenoma;
- 30 - 50 year olds
- Female > males
- 1-3cm in size at presentation
- Don’t need to know molecular changes! Just know Number of molecular changes happens within it
- Small, solitary soft and can often feel and move - solitary thyroid nodule
- Different types, sometimes functional
- If these look normal on cytology what do we do, surgery but may have normal levels that we don’t want to disrupt?
- We are looking if there is potential molecular changes that something may be going
What are the features of Papillary Carcinoma ?
Papillary Carcinoma;
- Around 80% of thyroid cancers
- 20-50 years old
- 3 females: 1 male
Causes;
- Radiation - e.g chernobyl
- Family history
- Unknown
Don’t need to know molecular changes! Just know Number of molecular changes happens within it
Called Papillary cause doesn’t look like follicles in histology looks like papillary arrangements with some microcalficiation and lump
What is this histological image showing?
Papillary Carcinoma - Called Papillary cause doesn’t look like follicles in histology looks like papillary arrangements with some microcalficiation and lump
What are the features of Medullary carcinoma ?
In thyroid this is from parafollicular cells and a neuroendocrine cell, classically produces amyloid and calcitonin and they can give rise to a tumour, but they’re neuroendocrine cells producing amyloid protein and cells full of calcitonin
Where do all cancers come from?
Primitive stem cells and then partly differentiate towards something
In thyroid we think there’s a primitive follicular stem cell and depending on mutations may become follicular adenoma, papillary carcinoma, anapaestic etc
What types of Parathyroid issues?
Tends to present with something functional happening, due to being behind thyroid
Hyperparathyroidism;
Absorbing high levels calcium, trying to excreting it, causing kidney stones
Primary Hyperparathyroidism (More common)
- Too much PTH being produced
Causes;
- Adenoma (focal lesion in parathyroid) - 4/5ths most common!
- Hyperplasia (some familial)
- Parathyroid carcinoma (less than 1%)
Secondary Hyperparathyroidism;
- Caused by low calcium (e.g chronic renal failure and vitamin D deficiency)
- Triggers PTH (further increases absorption calcium from bones)
Hypercalcaemia effects;
- Emotional disorders
- Muscle atrophy
- Parathyroid adenoma or hyperplasia
- Osteitis fibrosa cystica
- Peptic ulcer
- Pancreatitis
- Kidney stone
- Nephrocalcinosis
When 2 genetic conditions cause influence endocrine neoplasia ?
MEN 1 + MEN 2
Multiple Endocrine Neoplasia
- Issue is diagnosis, particularly if spontaneous with different functional diagnosis
- How are you going to treat multiple tumours
- What going to do about rest of family?
