thyroid nodules

Question 1

How are thyroid nodules usually discovered

Answer 1

Most are noted by patient, then noted by third party or detected by other tests. Ultrasound > CT > PET

Question 2

How common are thyroid nodules and how often are they cancerous

Answer 2

Nearly 60% of people will get a thyroid nodule but only 10-15% are cancer.

Question 3

List the most common benign and malignant thyroid masses

Answer 3

Benign: adenoma. Malignant: papillary (85-90%), follicular (5%), anaplastic (<2%), medullary (5%), lymphoma, sarcoma and metastatic are rare

Question 4

Types of follicular/hurthle cell carcinomas

Answer 4

1. minimally invasive- vascular or capsular invasion. 2. Widely invasive - more extensive

Question 5

Papillary carcinoma characteristics

Answer 5

well differentiated, lymphatic spread, excellent prognosis

Question 6

Papillary carcinoma histology

Answer 6

Papillae with vascular core, optically clear nuclei, neuclear pseudoinclusions, nuclear grooves, rare or absent mitoses, psammoma bodies

Question 7

Anaplastic carcinoma characteristics

Answer 7

older age group, poor survival, rapidly growing mass

Question 8

Patterns of anaplastic carcinoma

Answer 8

spindle cell, giant cells, squamoid cells

Question 9

Medullary carcinoma histology

Answer 9

Solid proliferation of cells with granular cytoplasm (C cells), Highly vascular stroma, Hyalinized collagen and/or amyloid, May have Psammoma bodies

Question 10

Immunostains for medullary carcinoma

Answer 10

Thyroglobulin negative, calcitonin positive, chromogranin positive

Question 11

Thyroid lymphomas

Answer 11

large fleshy masses and background of autoimmune thyroiditis

Question 12

List cancers which may metastasize to thyroid

Answer 12

melanoma, lung, head and neck, renal, breast, colon

Question 13

Workup for thyroid nodules

Answer 13

1. TSH. 2. If TSH is low, nuclear imaging. If TSH is high/normal ultrasound. 3. If ultrasound shows nodule, fine needle aspiration. If no nodule on US, don’t do FNA. 4. If FNA is benign, follow. If FNA is malignant, surgery. If FNA is inadequate, re-biopsy. If FNA is suspicious, scan.

Question 14

Papillary carcinoma of thyroid histology

Answer 14

Highly cellular, +/- colloid, nuclear enlargement and elongation, nuclear grooves and pseudoinclusions, multiple small to large nucleoli, psammoma bodies, papillary cellular aggregates

Question 15

define proto oncogene

Answer 15

Normal gene which codes for a protein that promotes normal cell division

Question 16

Define oncogene

Answer 16

Mutated gene which codes for a protein that causes unregulated cell division. Oncogene activation causes tumors

Question 17

Define tumor suppressor gene

Answer 17

Normal gene which codes for a protein that restrains cell division or that promotes cell differentiation, DNA repair or apoptosis. Tumor suppressor gene loss results in tumors

Question 18

Molecular mechanisms of papillary carcinoma

Answer 18

RE/PTC rearrangement (20%), Ras point mutation (20%), and/or BRAF point mutation (40%) leads to cell growth and division

Question 19

Molecuar mechanisms of follicular thyroid carcinoma

Answer 19

Pax8-PPARgamma gene rearangement/fusion leads to abnormal expression in thyroid cells and follicular thyroid carcinoma in 50%.

Question 20

Describe the progression of thyroid tumor development.

Answer 20

thyroid follicular cell > follicular adenoma (Ras methylation) > follicular carcinoma (Pax8-PPARgamma fusion) > anaplastic carcinoma (p53 and Beta catenin mutations). Also thyroid follicular cell > papillary thyroid carcinoma (RET/PTC, Trk, Met, Ras, BRAF mutations). Also thyroid follicular cell > hyperfunctioning adenoma (TSH-R, g protein mutations)