Endocrine surgery Flashcards
Causes of Primary hyperparathyroidism
Single or double adenomas (80-85%)
Multi-gland hyperplasia (15%)
Carcinoma (<1%)
Localisation studies for primary hyperparathyoidism
Technetium 99 Sestamibi - SPECT or SPECT-CT
85% successful
Co-localising US to increase specificity yada sensitive - 95% if concordant
Medical management of hypercalcaemia
Rehydration, furosemide diuresis, steroids.
Cinacalcet- given and continued on discharge til surgery
Bisphosphonates can also be used but take 48-72hrs
Surgical approach
Bilateral neck exploration or focused
IF cannot find need to check high in the neck, low in the thymus or thyrothymic ligament, carotid sheath and enclosed within thyroid
Hemithyroidectomy or mediastinal exploration should only be considered at a second operation
Secondary hyperparathyroidism
Excessive secretion secondary to low calcium causing hyperplasia of glands and raised PTH
Commonly caused by CKD, low Vitamin D or high dose phosphate
Pathophysiology of secondary hyperparathyroidism
initially FGF 23 from bones keeps phosphate levels down by increased excretion and decreasing 1 alpha hydroxylation.
AS disease progresses Kidneys become resistant to FGF-23 and decrease 1-alpha hydroxylation of Vitamin D - decreased phosphate excretion
Deficiency in Vit D cause reduced calcium reabsorption for urine, Gut and failing kidneys result in low calcium and high phosphate which triggers PTH secretion and growth of gland
Management of 2nd Hyperparathyroidism
Medical Tx - depends on aetiology
If Vit D deficient - replace - Cholecalciferol for 8 weeks
In CKD - managed bone disease and ectopic calcification
Use dietary phosphate restriction and phosphate binders and Vitamin D supplimentation and calcimimetic (cinacalcet - binds to calcium sensing receptor - decrases PTH)
Indications for surgery in 2nd
Prolonged severe hyperparathyroidism
Calciphylaxis
Refractory hyperpohsphataemia
Hypercalcaemia
Evidence of bone disease
Extraskeletal calcification
Surgery improves overall mortality of dialysis patients
Total (4 gland or subtotal (3 and a half glands)
Multinodular Goitre
Enlarged thyroid gland consisting of multiple nodules (toxic or non-toxic.
Most develop as a result of TSH stimulation secondary to low thyroid hormone levels
Nodules are extremely common - up to 60% of population have them
Symptoms and signs of goitre
Compressive symptoms
Dysphagia
Pembertons sign - distension of veins when arms raised - retrosternal extension
Red Flag - Rapid onset and progression, pain referring to ear, family Hx, Genetic condition (PTEN,MEN2,FAP), severe dysphagia, stridor and previous radiation exposure
Risk of recurrent laryngeal nerve injury and EBSLN
RLN -Approx 1% with benign goitre - thought to be relatively low risk
EBSLN - can be as high as 40%
Causes of hyperthyroidism
Graves disease
Antibody mediated activation of TRH receports
Toxic nodule with autonomous secretion
Thyroditis
Medications
Pituitary adenoma, struma ovarii
thyroid cancer
Management of hyperthyroidism
Betablockers for tachycardia and anxiety
Block and replace using Carbimazole (40-60mg OD) - more likely to induce remission
Remain of media for 12-18months
50% relapse rate
Definitive Tx is surgery or radioidodine
Investigation of adrenal mass
Check if functional (<10%)
Serum and urine metanephrines and normetanephrines - pheo
Serum K and renin to aldosterone ration - Conns
Sport cortisol and ACTH - Cushing
Testosterone and oestrogen - possible cancer
CT adrenal protocol - cancer has poor washout, >4cm (25% malignancy), high hounsfield units, poorly defines, irregular heterogenous or areas of necrosis
Well differentiated Thyroid cancer
Histological subtype of cancer from thyroid follicular cells
Papillary
Mixed Papillary follicular
follicular and Hurtle cell
Papillary subtype more common than follicular except in iodine deficient areas
Thyroid nodule US
BTA 2014 guidelines to allow uninformed reporting - U:
1- Normal
2-Benigh
3 - Indeterminate
4 - suspicious
5 - Malignant
Thy classification
BTA 2014
Smears must contain 6 or more groups of at least 10cells
Thy1 - Non diagnostic
thy2 - Non neoplastic (need 2 -3to6months apart)
Thy3c Atypical cells 9-20% risk of cancer - may need diagnostic lobectomy
Thy3 F - follicular lesions - requires diagnostic thyroidectomy due to 25-30% chance of malignancy
Thy4 - Abnormal and suspicious but not diagnostic (70% risk of cancer - requires diagnostic lobectomy)
Thy5 - malignant
Surgical management of well differential thyroid cancer
Tumours<4cm with no high risk features can be considered for hemithyroidectomy alone
High risk : over 45, widely invasive, LN or distant mets, angioinvasion, areas of poor differentiation, multifocal, extra capsular extension, Familial disease, PET positive
Prognosis of thyroid cancers
10yr survival after diagnosis with Papillary cancer is >90% for stage 1 dropping to 59% with mets
Follicular cancer is worse with 10yr survival approx 85%
Neck Limp with diarrhoea
Highly suggestive of medullary cancer - high serum calcitonin causing osmotic diarrhoea
Work up for medullary thyroid cancer
US and FNA
CT of the neck
Direct endoscopy if suspicion of invasion of airway or oesophagus
Serum calcitonin andCEA
Need to ask about MEN 2 syndrome - hypercalcaemia and pheochromocytoma and also family history (cancer, primary hyperparathyroidism, phoe)
Need Serum PTH and calcium as well as work up for pheochromocytoma
Surgery for medullary
Guided by calcitonin
>50 - central node and ipsilateral node direction
>200 contralateral node dissection
>500 consider mediastinal node
Total thyroidectomy
If Medullary thyroid and mets
Little options - palliative
Can consider external bean radiation, TKI and if severe side effects - cytotoxic chemo - 20% response
Medullary cancer genetics
Codon 634 mutation
means has MEN2A
50% risk of pheochromocytoma
If family found to have mutation
Need examination and US of thyroid, serum calcitonin and Serum CEA. Prophylactic thyroidectomy before 5 screening for pheochromocytoma starting at 11
Difference between pheochromocytoma and parganglioma
Both are pargangliomas - tumours of the neural crest
But pheos must originate from the adrenal gland
Both can secrete noradrenaline but only phews can secrete adrenaline
Symptoms of pheochromocystoma
HTN - usually on multiple agents
Anxiety
Tremors
sweating
Genetics of Pheochromocystoma
30% are genetic
Associated with MEN2, NF1, VHL and familial paraganglioma syndrome (PGL-4, SDHB)
Imaging for Pheochromocystomas
US can be useful
MIBG is most widely available
SPECT-CT or PET CT give useful info on lesions and possible Mets
GALLIUM DOTANOC - somatoastatin receptor specific
F-DOPA now functional scan of choice
Pre-medication prior to surgery
Usually Alpha blockade - Doxazosin or phenoxybenzamine til symtpomatic of postural drop
If not controlled then Beta blockade
Vasculature of adrenal gland
Multiple feeding arteries - Infraphrenic, arota and renal
Right side - Vein drains into IVC - short and thick - difficult to control if torn
Left - Drains into renal vein - more oblique
Follow Up
Histology - cellular, nests, humour cell spindles, necrosis, cellularity, mitotic figure, vascular invasion and extra-adrenal extension - Gives PASS score (out of 20)
Tumours classified as lower or higher risk of malignancy
Need follow up for signs of Mets and review of Metanephrines
Metastatic disease
Difficult to manage
Surgical excision
Chemo limited and may not offer benefit - vincristine and dacarbazine
Levels of the Neck
1-5 Lateral and 6-7 central
L1 Body of mandible, anterior belly of digastric and vertical plane of the submandilar glad posteriorly (a/b - anterior bell of digastric and hyoid)
L2 - Skull base and hyoid bone, sternocleidomastoid posterior (a/b - accessory nerve)
L3 - Hyoid superior and cricoid inferior. Sternocleidomastoid posteriorly and sternohyoid anterior
L4- Cricod superior, clavicle inferior, sternocleidomastoid posterior and sternohyoid anterior
L5- Sternocleidomastoid anterior, Traapezius posterior, mastoid superior, claavical posterior(a/b- line from inferior boarder of cricoid)
L6 Hyoid superior, sternal notch inferior, medial edge of carotid
L7 (controversial) nodal tissue behind sternum
Radical vs selective neck dissections
Radical - Levels 1-5 and IJV, SCM and spinal accessory nerve - extensive neck mets - high morbidity
Modified Radical - does not remove IJV, SCM or SAN unless involved - less morbidity by maintains oncological control
Selective - only takes levels related to the cancers
