Medullary Carcinoma of the Thyroid

Question 1

what is it?

Answer 1

Medullary thyroid carcinoma (MTC)
Relatively rare tumour
Derived from C-cells (neuroendocrine) – can secrete calcitonin
Composed of spindle or polygonal cells arranged in nests, trabeculae or follicles
Associated Amyloid deposition (amyloid represents deposition of an abnormally folded protein e.g. calcitonin)

Question 2

what % of thyroid carcinomas?

Answer 2

5%

Question 3

who gets it?

Answer 3

Can be sporadic (70%) – solitary nodule
Familial medullary carcinoma – bilateral/multicentric – C cell hyperplasia
Associated with multiple endocrine neoplasia (MEN IIA or IIB)
MEN can arise in very young patients
Sporadic and familial cases are seen in adults (40s-50s)

Question 4

how does it present?

Answer 4

neck mass with local effects 
- dysphagia
- hoarseness
- airway compromise 
paraneoplastic syndrome 
- diarrhoea (VIP production)
- Cushing's (ACTH production)

Question 5

how is it managed?

Answer 5

• Total thyroidectomy
• Local recurrence in 35% patients
• 5 and 10 year survival overall about 80% and 73%
• Good prognostic factors – Young age, Female, Tumour size, confined to the thyroid, no metasases
• Necrosis, many mitoses, squamous metaplasia, small cell morphology and <50% cells calcitonin positive and type of RET mutation predict more aggressive behaviour
• Some familial forms have more aggressive potential (MEN2B) – consider a prophylactic thyroidectomy as child