Week 3: Thyroid cancer

Question 1

Etiology of solitary thyroid nodule

Answer 1

BENIGN
-colloid nodule, goiter, multinodular goiter, Hashimoto's, hyperplastic nodule, cyst
-follicular adenoma, follicular neoplasm
MALIGNANT
-papillary carcinoma
-follicular carcinoma
-Anaplastic carcinoma
-lymphoma
-medullary Ca
-Hurthle cell Ca

Question 2

Evaluating a solitary thyroid nodule

Answer 2

• need to determine benign vs. malignant
  1. physical exam
• diffuse (benign), localized (more risk of neoplasm)
• larger than 2.5cm is worrisome
• hard lesion, painless, fixed lesion more worrisome
  2. Laboratory eval
• serum TSH, FT4, anti-TPO, serum Tg level
  3. Ultrasound
• radionuclide imaging (hot vs cold)
  4. Fine needle aspiration (FNA)

Question 3

Evaluation of ultrasound of solitary thyroid mass

Answer 3

• complex cysts: can harbor papillary cancers
• Hyperechoic: more consistent with (mcw/) benign
• hypoechoic: mcw/ malignant
• vascularity: increased blood flow mcw/ malignant
• calcifications: starry night appearance mcw/ malignant
• shaggy borders: infiltrative, malignancy

Question 4

Risk factors for thyroid neoplasm

Answer 4

• extremes of age
• subacute presentation
• increase in size
• family history
• x-ray or radiation exposure
• damage to recurrent laryngeal nerve-hoarseness

Question 5

Types of thyroid cancers

Answer 5

PRIMARY
-differentiated follicular cells: papillary (80%) or follicular (15%)
-non-differentiated follicular cells: anaplastic
-C cells: medullary Ca
-hodgkin’s lymphoma, SCC, fibrosarcoma
SECONDARY
-metastatic diseases

Question 6

Pathogenesis of thyroid cancer/ genetic mutatons

Answer 6

1. Ras oncogene
   - use tyrosine kinase signaling
2. PTC/red
   - may lead to papillary thyroid cancer
   - seen with radiation induced papillary CA
3. BRAF mutation seen in sporadic papillary CA
4. PPAR/PAX8 seen in follicular CA
5. p53 seen in anaplastic Ca

Question 7

prognostic parameters for thyroid cancer

Answer 7

1. metastasis
   none>local>distant
2. Age
   M

Question 8

Indications for 131-I ablation in papillary thyroid cancer

Answer 8

• metastatic disease
• tumor size >2.5 cm (relative)
• Age> 45 yo (relative)
• detectable post-op Tg level (relative)
• male gender (relative)

Question 9

Parameters for monitoring patients with differentiated thyroid cancer

Answer 9

1. Serum TSH levels
2. Serum Tg measurements
   - monitor while patient is on L-T4 suppression
   - rising value with L-T4 suppression suggests recurrent disease
   - need pre-op Tg level
3. 131 I whole body scan
4. anatomic imaging
   - Ultrasound, MRI, CT scan, PET

Question 10

What 3 factors produce serum Tg?

Answer 10

1. Thyroid mass (metastases)
2. Thyroid injury
   - surgery, RAI rx, thyroiditis
3. TSH

Question 11

Management of differentiated thyroid cancer

Answer 11

1. total thyroidectomy
2. L-T4 suppression (TSH<0.01)
3. Early detection of persistent/metastatic disease
   - serum Tg
   - 131 I WBS
4. 131-I ablation using risk stratification