Endocrine Surgery Flashcards
Dye used to identify parathyroid
Methylene blue
In what condition if the serum calcium likely to be low
Secondary hyoerparathyroidism
Monitoring for papillary thyroid cancer
Measurement of thyroglobulin levels
Papillary thyroid cancer
Papillary carcinoma
• Commonest sub-type
• Accurately diagnosed on fine needle aspiration cytology
• Histologically they may demonstrate psammoma bodies (areas of calcification) and so called orphan Annie nuclei
• They typically metastasise via the lymphatics and thus laterally located apparently ectopic thyroid tissue is usually a metastasis from a well differentiated papillary carcinoma.
Follicular thyroid cancer
Follicular carcinoma
• Are less common than papillary lesions
• Like papillary tumours they may present as a discrete nodule. Although they appear to be well encapsulated macroscopically there invasion on microscopic evaluation.
• Lymph node metastases are uncommon and these tumours tend to spread haematogenously. This translates into a higher mortality rate.
• Follicular lesions identified at FNAC are allocated either a THY 3a (atypical cells) or
THY 3f (follicular lesion) the latter group should undergo a hemithyroidectomy and the former a repeat FNAC
Anaplastic thyroid cancer
Anaplastic carcinoma
• Less common and tend to occur in elderly females
• Disease is usually advanced at presentation and often only palliative decompressic and radiotherapy can be offered.
Medullary thyroid cancer
Medullary carcinoma
• These are tumours of the parafollicular cells ( C Cells) and are of neural crest origin.
• The serum calcitonin may be elevated which is of use when monitoring for recurrence.
• They may be familial and occur as part of the MEN -2A disease spectrum.
• Spread may be either lymphatic or Haematogenous and as these tumours are not derived primarily from thyroid cells they are not responsive to radioiodine.
Which thyroid condition is associated with lithium use
Hypothyroidism
Lithium induced hypothyroidism and goiter may take weeks to years after it is started.
Studies have shown that the prevalence rates of lithium-induced hypothyroidism range from 3.4% to 52%, with a female-to-male ratio of approximately 5:1. The clinical presentation of hypothyroidism is similar to that of the patient’s not on lithium and the biochemical changes are identical to those in primary hypothyroidism. Hyperthyroidism can result but is less common. Routine monitoring of thyroid function should occur in all patients taking lithium.
Where are thyroglossal cysts most commonly located
Immediately below the hyoid bone
Pre-op meds for phaeochromocytoma
Phenoxybenzamine
a Blockers are the safest drugs to control the hypertension. The use of b blockers is dangerous and should be avoided.
Chemotherapy used for adrenocortical adenocarcinoma
Mitotane is the first line treatment for advanced disease and offers reasonable palliation.
Chemotherapy with cisplatin and rarely radiotherapy may be considered.
What antibody is used to identify Graves’ disease
TSH receptor antibodies (95%)
Antithyroid peroxidase and anti thyroglobulin are seen in a smaller percentage of cases.
Treatment for papillary thyroid cancer
Hemithyroidectomy can be considered the complete treatment for papillary cancers which are:
- <1 cm
-Unifocal
-No family history
- No radiation exposure
Node dissection of level VI nodes is sensible in high risk patients
Presence of Hurthle cells on histology
Hurtle cell lesions are a subtype of follicular thyroid cancer and considered to have an adverse prognosis. Almost all cases should be considered for total thyroidectomy and some surgeons would also undertake central nodal dissection.
Glucagonoma
90% of glucagonomas are malignant
70% will have necrolytic migratory erythema
Incidence of Recurrent laryngeal nerve injury
1.8% at 1 month which declines to 0.5% at 3 months
Parathyroid cancer
• Rare condition
• Equal gender ratio
• Marked hypercalcaemia, neck mass may be present and lesion usually larger than simple adenomas
• If suspected then en bloc resection of the affected half of the thyroid and adjacent soft tissues is performed
• Survival rates with en bloc, RO resection = 89% overall (5 years)
• Simple parathyroidectomy = 53% survival rate
When parathyroid cancer is suspected a radical excision is indicated without pre-operative tissue sampling. FNA assessments of these lesions are unreliable and core biopsy risks seeding the tumour through the strap muscles and may compromise cure. Histological criteria favouring malignancy include capsular invasion, mitoses and rosette like cellular architecture.
MIBG scan
Meta-iodobenzylguanidine scintiscans (MIBG) scans are indicated in the work up of suspected adrenal phaeochromocytoma for the detection of extra adrenal disease.
Presenting features of cushings
Presenting features:
Obesity 95%
Hirsuitism 80%
Hypertension 80%
Myopathy 60%
Buffalo hump 55%
Easy bruising 40%
Clear cells found on biopsy
Renal cell carcinoma are the tumour type most likely to metastasise to the thyroid. These will often have a clear cell morphology histologically. Clear cell sarcomas are very rare and thyroidal metastasis from them rarer still.
Adrenal mass follow up
Follow up Ct scan at 6, 12 and 24months for benign (<4cm tend low incidence)
3-6months if concerns
Risk of hypocalcaemia in thyroidectomy
5% - in 80% of these cases the situation resolved over the following 12 months
Which cancer is associated with non-therapeutic irradiation of the neck
Exposure to ionising radiation particularly in the young can predispose to thyroid cancer and 85% of these tumours are papillary. Papillary cancers that occur following radiation exposure should generally be treated by total thyroidectomy even if small.
Hashimotos thyroiditis antibodies
Antibodies to thyroid peroxidase are found in most patients with Graves disease or
Hashimotos thyroiditis.
USS features of malignancy
USS features of malignancy
• Hypochoity
• Microcalcifications
• Lymphadenopathy
• Loss of halo
• Irregular margins
PTH actions to increase serum calcium
PTH increases the activity of 1-a-hydroxylase enzyme, which converts 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol, the active form of vitamin D.
Osteoclasts do not have a PTH receptor and effects are mediated via osteoblasts.
Measurement of thyroglobulin levels are most likely useful in which cancer
Thyroglobulin is synthesized by the follicular cells of the thyroid and levels are more likely to be elevated in well differentiated follicular thyroid cancers in which it can be used to screen for recurrence.
