Endocrine

Question 1

What is thyroid scintigraphy?

Answer 1

• Investigate the functioning of nodules
• Hot nodule – increase uptake
• Cold nodules – reduced uptake
• Functional (hot) nodules more likely to be benign

Question 2

What is fine needle aspiration cytology (FNAC) and how is it used for the thyroid?

Answer 2

• Ultrasound evaluation – > FNAC
• gold standard test – evaluation of thyroid nodule
• Nodules > 1cm
• Palpation or ultrasound guided
• 23-27 gauge needle
• Safe, accurate and cost effective

1.Thy 1 Non-diagnostic: Cancer risk 5% to 10% (Bethesda)
2.Thy 2 Benign: Cancer risk 0% to 3%
3.Thy 3a Atypia of undetermined significance: Cancer risk 10 to 30%
4.Thy 3f Follicular neoplasm (or suspicious for follicular neoplasm): Cancer risk 25% to 40%
5.Thy 4 Suspicious for malignancy: Cancer risk 50% to 75%
6.Thy 5 Malignant: Cancer risk 97% to 99%

Question 3

Benign vs malignant thyroid conditions

Answer 3

Benign:
Thyroid adenoma/follicular adenoma

Malignant:
Follicular thyroid carcinoma
Papillary thyroid carcinoma
Medullary carcinoma
Anaplastic carcinoma

Question 4

What is papillary thyroid carcinoma?

Answer 4

• Commonest thyroid cancer - > 85% of the cases
• Solitary or multifocal
• Well-circumscribed or encapsulated or infiltrative

Pathology:
• Branching papillae (follicular variant)
• Optically clear/empty nuclei/ grooves/pseudoinclu
sions
• “Orphan Annie Eye” nuclei

Clinical course:
- cervical lymph nodes

Question 5

Thyroid/follicular adenoma vs carcinoma

Answer 5

Adenoma:
• Benign tumour
• Presents as a solitary painless lump
• Large – pressure symptoms, difficulty swallowing
• Investigations – radioiodine scan – less uptake “Cold nodule”
• Fine needle aspiration cytology (FNAC) – Thy3f
• Treatment – excised with capsule intact

Carcinoma:
• Malignant tumour
• 5-15% of primary thyroid carcinoma
• Solitary nodule, slowly enlarging
• Frequently cold on scintigraphy, but may appear warm

Question 6

What is anaplastic carcinoma of the thyroid?

Answer 6

• Anaplasia – lack of differentiation “to form backwards”
• Aggressive tumour, mean age -65 years
• Invasion of neck structures – dyspnea, dysphagia, hoarseness, cough
• Metastasis
• Mortality rate approaching 100%

Question 7

What is medullary carcinoma of the thyroid?

Answer 7

• Parafollicular cells or C cells
• Neuroendocrine tumours
• Calcitonin levels
• 70% sporadic rest associated with MEN 2A/2B

Question 8

What is Multiple endocrine neoplasia (MEN)?

Answer 8

• Genetically inherited diseases – autosomal dominant
• proliferative/neoplastic disorders in multiple endocrine organs
• Asymptomatic stage – hyperplasia in cell of origin
• Tumours occur at younger age
• Can occur in multiple endocrine organs – synchronously (at the same time) or metachronously (at different times)

Question 9

What does MEN1 lead to?

Answer 9

• Pituitary adenoma (40%)
• Parathyroid adenomas (95%)
• Pancreatic endocrine tumours (30%)

Question 10

What does MEN2A lead to?

Answer 10

• Medullary thyroid carcinoma (100%)
• Parathyroid adenoma
• Phaeochromocytoma (50%) - bilateral

Question 11

What does MEN2B lead to?

Answer 11

• Medullary thyroid carcinoma (100%)
• Phaeochromocytoma (50%)
• Neuromas in tongue and lips