Thyroid Nodules & Thyroid Cancer

Question 1

thyroid nodules (adenomas) - overview

Answer 1

*very common, more common with increasing age
*90-95% of thyroid nodules and benign and non-functioning
*some nodules can be toxic and can cause hyperthyroidism; additionally, you can have a toxic multinodular goiter
*the remaining 5-10% are malignant

Question 2

evaluation of thyroid nodules - 2 questions

Answer 2

1. is it a toxic nodule / is it making excess thyroid hormone?
   -measure TSH; if low, get radioactive iodine uptake & scan
2. is it cancer?
   -ULTRASOUND, then fine needle biopsy depending on features

Question 3

what is the best way to evaluate thyroid nodules?

Answer 3

*ULTRASOUND!
*allows us to risk stratify and decide which nodules need to be biopsied
*indications for fine needle aspiration (FNA) biopsy: nodule > 1 cm and has suspicious characteristics

Question 4

papillary carcinoma of the thyroid - overview

Answer 4

*most common thyroid malignancy; one of the “well-differentiated” thyroid cancers
*cell origin = follicular epithelial cells
*prognosis = good
*tumor marker = thyroglobulin

Question 5

papillary carcinoma of the thyroid - pathologic features

Answer 5

*empty-appearing nuclei with central clearing (Orphan Annie eyes)
*Psammoma bodies: laminated, concentric spherules with dystrophic calcification
*nuclear grooves
*cells form papillae instead of follicles

Question 6

psammoma bodies - image & associated condition

Answer 6

*laminated, concentric spherules with dystrophic calcification
*associated with papillary carcinoma of the thyroid

Question 7

orphan annie eyes - image & associated condition

Answer 7

*empty-appearing nuclei with central clearing
*associated with papillary carcinoma of the thyroid

Question 8

papillary carcinoma of the thyroid - genetic mutation

Answer 8

*BRAF mutation

Question 9

what is the most well-known risk factor for development of well-differentiated thyroid cancer?

Answer 9

*history of RADIATION to the neck

Question 10

papillary carcinoma of the thyroid - treatment

Answer 10

*SURGERY +/- radioactive iodine +/- TSH suppression (via extra levothyroxine)
*sometimes, we just watch the cancers and wait

Question 11

complications associated with thyroidectomy

Answer 11

*transient or permanent hypoparathyroidism (parathyroid glands can be either “stunned” or removed/permanently damaged)
*damage to recurrent laryngeal nerve: results in hoarse voice, trouble swallowing
*damage to external branch of superior laryngeal nerve: primarily affects singing voice

Question 12

follicular carcinoma of the thyroid - overview

Answer 12

*well-differentiated thyroid cancer; good prognosis
*invades tumor capsule and vasculature, uniform follicles
*pathologic feature = microfollicles
*associated gene mutations: RAS, PAX8-PPAR gamma
*tumor marker = thyroglobulin

Question 13

thyroglobulin as a tumor marker

Answer 13

*we measure thyroglobulin to check for recurrence in well-differentiated (papillary, follicular) thyroid cancer
*thyroglobulin: a precursor for thyroid hormone, and used to store thyroid hormone in the follicles once made; only comes from thyroid tissue
*if a person has a total thyroidectomy, the thyroglobulin should be undetectable; if it is increasing, this suggests thyroid cancer recurrence

Question 14

medullary thyroid cancer - overview

Answer 14

*cell origin = C-cell (parafollicular cells)
*characterized by amyloid deposition on pathology
*tumor marker = calcitonin

Question 15

medullary thyroid cancer - associated gene mutation

Answer 15

*RET mutation:
- about 25% associated with MEN2 syndrome

Question 16

anaplastic thyroid cancer - overview

Answer 16

*rapidly growing over a couple months (as opposed to the other thyroid cancer, which grow very slowly)
*locally invasive/destructive
*metastasizes to distant sites easily
*poor prognosis; nearly universally fatal (unable to catch early enough and achieve surgical cure)