8. Thyroid carcinoma.

Question 1

Thyroid carcinoma - Incidence and stats

Answer 1

2 in 100,000 individuals

Affects women 2x more than men in pre-existing goiters.

Question 2

Thyroid carcinoma - Etiology

Answer 2

Following radiation of neck in childhood

Question 3

Thyroid carcinoma - Classification:

Answer 3

1. Papillary
2. Follicular
3. Medullary
4. Anaplastic

Papillary and Follicular are differentiated type. 90% of all thyroid cancers. Curable if detected early

Question 4

Thyroid carcinoma - Pathology

Answer 4

Papillary carcinoma: (hurthle cell) most common type. Young adults + children. Slow growing + lymphatic spread occurs late. Encapsulated. Dependent on TSH stimulation.

Follicular carcinoma: young + middle aged adults. More common in areas where endemic goitres are more common. Hematogenous spread (bone (flat bones), lung, liver)

Medullary carcinoma: arises from parafollicular C (hyperplasia) cells + may secrete calcitonin. Any age. Deposits of amyloid b/w nests of tumour cells. Affects both thyroid lobes. Calcitonin acts as tumour marker + used in screening in syndromic families (as can be familia)

Diagnostic = fine needle aspiration.
- Tx: total thyroidectomy + central lymph node dissection. If cervical lymphadenopathy = radical needle dissection

Anaplastic carcinoma: elderly. Rapid local spread with compression + invasion of trachea. V. poor prognosis = 1yr survival. Aim of tx = local control of disease.

Question 5

Thyroid carcinoma - Anaplastic Carcinoma - Clinical Presenatation

Answer 5

Tumour may present like goitres as lump in neck, more rapidly growing.

Dysphagia is uncommon + suggests of anaplastic CA. complaint of swelling discomfort.

Pain with local infiltration + hoarseness is suggestive of infiltration of recurrent laryngeal nerve.

Deep cervical lymph nodes may be palpably enlarged. Pt usually euthyroid.

Question 6

Thyroid carcinoma - Anaplastic Carcinoma - Diagnostic Investigations

Answer 6

x-ray of neck

radioiodine scans show cold nodules.

Ultrasound guided core needle biopsy/fine-needle aspiration cytology to confirm dx.

Question 7

Thyroid carcinoma - Anaplastic Carcinoma - Treatment

Answer 7

Well differentiated tumours can be treated by a combination of surgery, thyroid suppression by thyroxine + radioiodine

o Total thyroidectomy for pt at high risk of recurrence according to prognostic scoring systems

Prognostic factors (tumour size, presence of lymph nodes metastasis + older age) = increased risk of recurrence

o Thyroid lobectomy – appropriate for unifocal, papillary tumours less than cm in diameter in absence of lymph nodes metastasis

o Pt with differentiated thyroid cancer will require total thyroidectomy + radioactive therapy

Question 8

Thyroid carcinoma - Other Treatments

Answer 8

• Medullar + anaplastic = total thyroidectomy
• Follicular + papillary = subtotal lobectomy

Radioiodine ablation: iodine 131 ablation of thyroid bed – complication = edema, swelling or thyroiditis

TSH suppression = post op thyroxine therapy

Thyroglobulin – best way of detecting presence of normal or malignant thyroid tissue – pt free of disease = undetectable levels

Question 9

Anatomical steps of thyroidectomy

Answer 9

a. Skin incision
b. Subplatysmal flaps + platysma divided
c. Separating the strap muscles + exposing the ant surface of the thyroid
d. Identify the middle thyroid vein
e. Identify the sup laryngeal artery + the external laryngeal nerve
f. Identifying superior parathyroid gland
g. Identify inf parathyroid gl
h. Identify the recurrent laryngeal nerve
i. Dividing the thyroid isthmus
j. Removing the thyroid gl