Thyroid and breast activity Flashcards
Which muscle divides the anterior and posterior triangles of the neck?
Sternocleidomastoid
What are the important muscles in the anterior neck to be aware of?
Strap muscles (infrahyoid, sternohyoid, and omohyoid) The sternocleidomastoid muscle; and The longus colli muscle.
Briefly describe the anterior triangle of the neck
The anterior triangle is an inverted triangle with its base above and the apex pointing downwards at the manubrium of the sternum. It can be further subdivided into smaller triangles by the crossing of digastric and omohyoid muscles.
What are the boundaries of the anterior triangle of the neck?
- anterior: median line of the neck
- posterior: anterior margin of sternocleidomastoid
- base: inferior border of the mandible
• the roof of platysma muscle and subcutaneous tissues;
• the floor, formed by the pharynx, larynx and thyroid gland;
• the apex which is the jugular notch; and
• the base, which is a line from the inferior border of the mandible to the mastoid process.
What are the subdivisions of the anterior triangle of the neck?
The anterior triangle is subdivided into 3 ½ triangles by the anterior and posterior bellies of digastric muscle and superior belly of omohyoid muscle. The subdivisions are as follows:
- digastric (submandibular) triangle
- muscular triangle
- carotid triangle
- submental triangle (half, only because there is only one submental triangle)
What are the borders of the posterior triangle of the neck?
- the posterior border of sternocleidomastoid muscle;
- the anterior border of the trapezius muscle;
- the middle third of the clavicle, forming the base of the triangle;
- the roof, formed by cervical fascia; and
- the floor, formed by muscles and deep cervical fascia.
What are the subdivisions of the posterior triangle?
The posterior triangle can then be subdivided into the occipital triangle and the supraclavicular or subclavian triangle.
Briefly describe the contents of the posterior triangle
The posterior triangle contains mostly vessels and nerves that connect the neck and the upper limb. It also contains superficial and deep lymph nodes.
Breifly describe the anterior triangle and it’s contents
The anterior triangle contains glandular structures (such as the thyroid and parathyroid glands) and lymphatics. The carotid triangle in particular contains the carotid vessels and associated veins and nerves.
What is the term for the normal secretion of thyroid hormones?
euthryroid
List the laboratory tests used to assess the parathyroid gland
Alkaline phosphatase, calcium, parathyroid hormone (PTH)
List the laboratory tests used to assess the thyroid gland
Radioactive Iodine Uptake (RAIU), TSH level, t$ (thyroxine), T3 (tri-iodothyronine).
List the laboratory tests used to assess the thyroid gland
Radioactive Iodine Uptake (RAIU), TSH level, T3 (thyroxine), T3 (tri-iodothyronine).
What does Radioactive Iodine Uptake (RAIU) test?
Thyroid function
What does TSH do and how does it affect T3 and T4.
TSH is secreted by the anterior pituitary on stimulation by TRH from the hypothalamus. TSH stimulates the release of T3 and T4 by the thyroid. T4 is secreted by the thyroid gland in response to TSH; only a small amount circulates freely in blood. T3 is the more potent thyroid hormone and is secreted in response to TSH.
Describe the laboratory tests that would be used in a patient that presents with the following clinical features.
Draw possible conclusions as to the cause of these symptoms.
Describe the most common condition that may cause these symptoms.
Feeling hot, increased sweating, weight loss, enlargement of the thyroid gland, rapid heart rate and palpitations, anxiety and restless hyperactivity.
A patient with the described clinical features is presenting with common features of Graves’ disease with hyperthyroidism. Laboratory tests would be performed to identify TSH levels, T3 and T4. T3 and T4 will be elevated above normal ranges. TSH will be decreased due the feedback mechanism not requiring further TSH secretion in the presence of increased T3 and T4 circulating in the blood. RAIU could be also performed, but the other tests are more specific as hyperthyroidism does not always cause high iodine uptake.
Graves’ disease is the most common diffuse abnormality of the thyroid gland. It is an auto-immune disorder in which antibodies are produced against TSH receptors. These are called thyroid-stimulating antibodies which bind to TSH receptors and stimulate thyroid hormone secretion (other terms for this antibody you may come across are long-acting thyroid stimulator or thyroid-stimulating immunoglobulins).
Graves’ disease generally occurs in younger women, and may cause exophthalmos (protruding eyeballs), smoothly enlarged thyroid, increased appetite, weight loss, muscle wasting, diarrhoea, increased nervousness and excitability, raised blood pressure, warmth, sweatiness and amenorrhoea.
Describe the laboratory tests that would be used in a patient that presents with the following clinical features.
Draw possible conclusions as to the cause of these symptoms.
Describe the most common condition that may cause these symptoms.
Cold intolerance, facial and extremity oedema, lethargy, weight gain, bradycardia, constipation, hair loss.
A patient with the described clinical features is presenting with common features of hypothyroidism. Laboratory tests would be performed to identify TSH levels, T4 and T3. TSH will be elevated above the normal range as it is further secreted due to low circulating levels of T3 and T4. This is a sensitive early marker. A RAIU test could be also performed and would show reduced iodine uptake.
Hashimoto’s thyroiditis is the most common cause, clinically presenting with reduced thyroid function and the symptoms of myxedema due to reduced metabolic rate. This is an auto-immune disease that presents more often in women than men. Occasionally the initial tests in Hashimoto’s thyroiditis may show hyperthyroid levels, but usually the patient does not present until the disease has passed through the euthyroid state into an increasing hypothyroid state.
Symptoms of this disease are as described in the case history; the thyroid gland is usually prominent and ‘rubbery’ to palpate. TSH tests can be further used to monitor the effectiveness of the thyroid hormone replacement therapy used to treat the disease. Other causes of these symptoms may be previous thyroidectomy or low iodine intake.
Describe the laboratory tests that would be used in a patient that presents with the following clinical features.
Draw possible conclusions as to the cause of these symptoms.
Describe the most common condition that may cause these symptoms.
Prominent, irregular neck swelling, difficulty in swallowing, occasional neck pain.
A patient with the described clinical features is presenting with common features of multi-nodular goitre. Laboratory tests would be performed to identify RAIU, TSH levels, T3 and T4. These may all show normal levels, unless there is a dominant functional adenoma that will cause an elevation of the RAIU, T3 and T4 tests, with a reduction in the TSH levels. Usually these goitres are euthyroid in nature.
Multinodular goitre may present as a generalised enlargement of the thyroid gland or it may have irregular margins with variable sized, palpable nodules. Often one nodule may rapidly increase in size due to internal haemorrhage into the nodule. This can cause pain and increase the patient’s symptoms of dysphagia.
Describe the laboratory tests that would be used in a patient that presents with the following clinical features.
Draw possible conclusions as to the cause of these symptoms.
Describe the most common condition that may cause these symptoms.
History of renal calculi, unilateral (mild) neck swelling.
A patient with the described clinical features is presenting with common features of parathyroid adenoma. Laboratory tests that would be performed will assess serum calcium and parathormone levels. Both of these will be elevated. This effectively rules out a malignant cause of the palpable mass as you would expect the parathormone levels to be suppressed with malignancy.
Parathyroid adenomas are often small, but may enlarge to be palpable. Careful assessment to look for additional enlarged glands is important, so as to rule out parathyroid hyperplasia.
briefly describe thyroid embryological development.
The thyroid gland is the first endocrine gland to form in the embryo. It appears during the fourth embryonic week as a median endodermal thickening in the floor of the primitive pharynx which forms a downgrowth known as the Thyroid Diverticulum. The developing thyroid descends through the tissues of the neck at the end of a slender thyroglossal duct, which breaks down by the end of the fifth embryonic week. The isolated thyroid gland continues to descend, reaching its final resting place just inferior to the cricoid cartilage by the seventh week. The only remnant, normally, of the thyroglossal duct is the foramen caecum of the tongue.
describe which transducer(s) you would use to perform the ultrasound scan:
1.(a) thin patient, small thyroid lobes;
A high-frequency (10 MHz or higher) linear probe is preferred for head and neck ultrasound, because it provides optimal resolution. If the long axis of the thyroid lobes can be fully imaged by that transducer, then no other will be required. If not, then a high frequency convex linear array may be required to adequately assess the true length of the lobes, otherwise dual imaging can be utilised.
describe which transducer(s) you would use to perform the ultrasound scan: thick-set patient with thyroid gland enlargement
Lower-frequency probes with deeper sound penetration but less spatial resolution may be needed in the setting of a large patient body habitus or to evaluate large thyroid glands.
initially, a high frequency linear array transducer should be used. It may be necessary to reduce the operating frequency if possible to get better depth penetration. A mid to high frequency convex linear array transducer may then be required to further image the gland, to allow better imaging of any retrosternal extension and to fully image the length of each lobe. Dual imaging may be helpful with the linear array to measure the gland dimensions if available.
describe which transducer(s) you would use to perform the ultrasound scan: average size patient with a normal thyroid gland;
a high frequency linear array transducer should be the transducer used for all imaging, except for the longitudinal dimensions if dual imaging is not available. In this case a high frequency convex linear transducer should be used.
describe which transducer(s) you would use to perform the ultrasound scan: palpable, superficial mass, ? thyroid in origin.
initially, a high frequency linear array transducer should be used to examine the thyroid gland and neck region. A high frequency convex linear array may then be required to adequately assess the true length of the lobes, otherwise dual imaging can be utilised. The mass should be further examined, due to its superficial nature, by a high frequency compact linear type probe if available to obtain better near-field resolution. If one is not available in your department, utilise a gel stand-off pad as this will help to reduce near field reverberations.
Using a line diagram, draw the planes in which you would measure the thyroid gland.
Transverse: • Widest diameter of each lobe • AP diameter of the isthmus Longitudinal: • longest length/bi-polar measurement of each lobe and a depth measurement in this plane at the deepest section of the lobe.
During the course of the scan, a patient who has until now been accepting of the procedure, refuses to continue with the scan any longer. List reasons why this patient may have withdrawn consent.
Environmental factors:
• the room may be too hot, too cold, too noisy, too smelly.
• the bed or scanning position may be too uncomfortable to tolerate further.
Sonographer factors:
• you may not have explained the procedure fully to the patient and are doing something they did not expect.
• you may be communicating poorly with the patient, ignoring them, being rude or not explaining what you are doing.
• Pressing too hard on their neck while scanning, causing pain or difficulty in swallowing or breathing.
• Leaning on the patient’s chest/breasts, even if inadvertantly.
Department factors:
• Rudeness of staff, whether real or perceived; this may include the receptionist, nurse/aid, sonographer or sonologist.
• Continual interruption in the ultrasound room by other staff members or phone calls.
• Excessive waiting while checking the films or seeking the sonologist.
Patient/disease process factors:
• Some patients with abnormally functioning thyroid glands may experience episodes of paranoia and/or depression. They may be very sensitive to anything you may say to them.
• The neck or mass may be very tender, especially when being scanned.
• The patient may be afraid of what the abnormality may be; e.g. cancer. This may be exacerbated if there is a relevant family history or if they are present due to a recurrence of a previous problem.
Summarise fine needle aspiration biopsy advantages and disadvantages
Fine needle aspiration biopsy Advantages: • minimal materials (usually a very simply procedure) • inexpensive • quickly performed • local anaesthetic often not used • minimal discomfort (usually) • small bruise only (usually)
Disadvantages:
• sample may be inadequate ( reduced if pathologist is present to check sample )
• false positive/false negative/equivocal aspirates
• dependence of cytopathology expertise
• specific tissue-related potential pitfalls.
Summarise core biopsy advantages and disadvantages
Core Biopsy Advantages: • inexpensive • relatively atraumatic • may obviate the need for open biopsy • higher diagnostic yield (though there is some varying opinion about this)
Disadvantages:
• greater chance of local haemorrhage due to larger bore needle used
• tracheal perforation and other complications as there is probably reduced control of the needle depth with this procedure compared to FNA.
• potential for facial nerve damage
• possibility of tumour seeding, but very little evidence.
Ultrasound features that favour a benign thyroid lesion:
1.Internal consistency
• Solid, this is variable as malignant nodules may also be solid.
• Cystic, many benign nodules undergo cystic degeneration or internal haemorrhage and therefore have cystic components, though some malignant lesions have cystic varieties and may also undergo necrosis.
• “Comet-tail‟ artefacts within a mixed or cystic mass are generally associated with benign colloid nodules
2.Echogenicity compared with normal thyroid tissue
• Hyper-echoic nodules are more likely to be benign, then iso-echoic.
3.Margination
• Margins are usually well-defined, smooth and sharp.
4.Calcification
• If calcifications are present, they are usually coarse and irregularly distributed, or have a peripheral (“egg shell‟) pattern.
5.Peripheral anechoic halo
• A complete, thin halo is more common in benign lesions. The halo is caused either by the capsule of the nodule or compressed thyroid vessels.
6.Co-existing multinodularity
• Multiple nodularity used to be an indicator for benign disease, but benign and malignant disease can co-exist, though this is not common.
• Solitary nodules are statistically going to be benign due to the low incidence of thyroid carcinoma.
7.Vascularity
• The most common vascular pattern is peripheral flow with little internal flow, if at all.
• There will be no flow in septae.
• Functioning adenomas may have increased internal flow, so need to be correlated with an isotope scan as they should be “hot‟.
8.Surrounding structures
• No invasion of the margins of lesion or local spread should be seen.
• There should be no associated adjacent lymphadenopathy, unless inflammatory in nature.
Ultrasound features that favour a malignant thyroid lesion
1.Internal consistency
• Usually have a solid appearance, but may be mixed and/or cystic (for example, papillary carcinoma).
2.Echogenicity compared with normal thyroid tissue
• Hypo-echoic or iso-echoic are usually seen.
3.Margination
• Margins are usually irregular and poorly-defined.
4.Calcification
• Punctate, fine scattered (for example, psammoma bodies in papillary carcinoma) calcifications are often found, but those with medullary carcinoma may be more coarse.
5.Peripheral anechoic halo
• A partial, thick halo may be present or no halo seen.
6.Co-existing multinodularity
• Malignant lesions are usually solitary (though papillary carcinoma may be multi-centric).
7.Vascularity
• Malignant nodules may have very variable flow patterns, but a nodule with increased peripheral flow, multiple vascular poles and chaotic, internal flow is more likely to be malignant, especially if it is a cold lesion on an isotope scan.
• Vascularity within septae is a good indicator of a malignant cystic lesion.
8.Surrounding structures
• Invasion of any capsule of the lesion is common.
• Local invasion, that is, involvement of the strap muscles (as seen by a loss of fascial planes between the strap muscles and the thyroid gland with ill-defined muscle outline), involvement of the trachea, oesophagus and recurrent laryngeal nerve) is a good indicator of malignant disease.
• Associated lymphadenopathy is also common.
Describe the ultrasound appearance of parathyroid adenoma
- Usually affects only one gland but may be multiple.
- They are typically discrete and oval.
- Usually small, 8-15 mm, but have been known to be up to 5cm in diameter.
- A large adenoma may become complex in appearance when large due to cystic degeneration,internal haemorrhage and/or necrosis.
- Rarely are calcifications present.
Describe the ultrasound appearance of parathyroid cyst
- More common in women and usually occurs in one of the inferior glands.
- Well-defined and thin-walled with anechoic centre. Some may have some internal debris or septae.
Describe the ultrasound appearance of parathyroid hyperplasia
- It is not possible on ultrasound to differentiate between primary and secondary parathyroid hyperplasia as in both cases the glands have increased as a compensatory mechanism
- All four glands are symmetrically and equally enlarged.
- Hypo-echoic, usually, but may be iso-echoic compared to the thyroid gland.
- Calcifications may be present.
- Whilst oval in shape, hyperplastic parathyroid glands are typically more spherical than adenomas.
- Usually hyperplastic glands are quite vascular with arterial internal flow.
Describe the ultrasound appearance of parathyroid carcinoma
- Usually affects only one gland and is quite rare.
- They are usually hypo-echoic when compared to the thyroid gland.
- Carcinoma may be lobulated and heterogenous due to necrosis.
- Local invasion may be noted and adjacent lymphadenopathy.
- Calcifications may be present.
