thyroid Flashcards
What histological features are seen in papillary thyroid cancer
Orphan Annie nuclei
psammoma bodies
Psammoma bodies also seen in ovarian cancer and meningioma
Why can follicular thyroid cancer not be diagnosed on FNA
Needs capsule or vascular invasion, so can only be seen at thyroidectomy
What is the complication of Hurthle cell variant FTC
Does not take up RAI
What cells do medullary thyroid cancer arise from
What needs to be screened for
What is the treatment for MTC
Parafollicular c cells
Need to be screened for MEN2
Tx is surgery as far as possible
What features distinguish FAP from Gardners syndrome
Extra teeth
Colorectal adenomatous polyps, osteomas (skull & mandible), desmoid tumours, desmoid cysts, sebaceous cysts
What is Turcot syndrome
AD
Colonic polyps associated with CNS tumours (ependymomas and medulloblastomas)
Increased risk of thyroid/adrenal/BCC
What is Cowdens syndrome and what is the lifetime risk of thyroid cancer
AD PTEN mutation - hamartoma syndrome
30-40% lifetime risk of thyroid cancer (follicular, then papillary)
Also breast, endometrial, colorectal, melanoma
How is a T1 thyroid cancer defined
T2
tumour <2cm
T1a = <1cm
T1b = 1-2cm
T2 = 2-4cm
How is a T3 thyroid cancer defined
T3a - >4cm but limited to thyroid
T3b - extra thyroid extension
How is a T4 thyroid cancer defined
T4a - Local invasion into trachea, larynx, oesophagus, recurrent laryngeal nerve
T4b - Invasion into prevertebral fascia, mediastinal vessels or carotids
How is thyroid nodal staging defined
N1a - Involvement of level 6 or 7
N1b - involvement elsewhere
When is cross sectional imaging indicated for thyroid cancer
T3-4 disease ie evidence of local invasion or tumour >4cm
What are the indications for a hemithyroidectomy
T1a (<1cm) - T2 differentiated thyroid cancer
What are the indications for a total thyroidectomy
T3-4
Nodal involvement
Extra-thyroid spread, multifocal disease
High risk features
Pre-RAI - distant mets
What are the indications for radioactive iodine
Post total thyroidectomy
Tumour >4cm (T3)
>T1b with unfavourable characteristics (Tall cell, Columnar, Insular, Diffuse sclerosing papillary cancer, Poorly differentiated)
Gross extra-thyroidal extension
Distant metastases
Recurrence
RAI not indicated if all of:
Tumour <1cm unifocal or multifocal
Classic papillary or follicular variant of papillary or follicular thyroid cancer
No vascular invasion AND no extra-thyroid extension