Thyroid Nodules

Question 1

How common are thyroid nodules?

Answer 1

nearly 60%

-risk of cancer in a thyroid nodule is small (10-15%), but not insignif

Question 2

Thyroid neoplasms

Answer 2

Benign: adenoma
malignant:
papillary (85-90%): multifocal, LN
follicular/hurthle (5%): vascular spread
Anaplastic (2%) very aggressive
medullary (5%) familial

Question 3

Thyroid adenoma

Answer 3

benign neoplasm
-Solitary nodule
Follicular / Hurthle cell
DDx: hyperplastic nodule
              follicular carcinoma (to tell difference: evaluate surgical specimen):
Careful evaluation of the capsule

Question 4

Follicular/Hurthle cell carcinoma

Answer 4

two types:
minimally invasive (vascular or capsular invasion)

widely invasive: more extensive invasion

Question 5

Papillary carcinoma

Answer 5

Most common
Well-differentiated
Multifocal
Lymphatic spread
Excellent prognosis

-fingerlike papillary projections
-Microscope: nuclear features:
Papillae with vascular core
Optically clear nuclei (“orphan annie eyes”)
Nuclear pseudoinclusions
Nuclear grooves
Rare or absent mitoses
Psammoma Bodies

Question 6

Anaplastic carcinoma of thyroid gland

Answer 6

Older age group (poor survival)
Rapidly growing mass
Three patterns:
-Spindle cell
-Giant cells
-Squamoid cells
Necrosis and hemorrhage

Question 7

Medullary carcinoma

Answer 7

Solid proliferation of cells with granular cytoplasm (C cells)
Highly vascular stroma
Hyalinized collagen and/or amyloid
May have Psammoma bodies
Immunostains:
Thyroglobulin -, Calcitonin +, Chromogranin +

Question 8

Lymphomas

Answer 8

Background autoimmune thyroiditis
Large fleshy masses
DDx : anaplastic ca of thyroid
Positive LCA, usually B-cell 
Gene rearrangement

Question 9

Clinical Eval

Answer 9

Hx:
growth
pain
cough, voice change

Physical Exam:
size, consistency, fixation, lymphadenopathy

Irradiation
FH

High clinical suspicion
Rapid tumor growth
Very firm nodule (rock hard)
Fixation to adjacent structures
Vocal cord paresis
Enlarged regional lymph nodes
Family history of PTC or MEN 2
Distant metastases

Question 10

Approach to pt w/ thyroid nodules

Answer 10

**look at flow chart:
esp get TSH, Diagnostic US, Fine needle aspiration biopsy

Benign: follow most
malignant: surgery
inadequate: rebiopsy
suspicious/indeterminate: scan

Biopsy:
onto slide
alcohol fixative
dipquick stain

Question 11

Papillary carcinoma of thyroid cytologic features

Answer 11

Highly cellular aspirate
\+/- colloid
Nuclear enlargement, elongation
Nuclear grooves, pseudoinclusions
Multiple small to large nucleoli
Psammoma bodies (calcifications)
Papillary cellular aggregates

Question 12

Bethesda system

Answer 12

6 diagnostic categories:
non-diagnostic
benign (0-3%), clinical f/u
ACUS (5-15%), repeat FNA
suspicious for follicular neoplasm (15-30%) lobectomy
susp for malig (60-75%) thyroidectomy
malig (97-99%) thyroidectomy

also lists risk of malignancy and usual management

Question 13

tumors result from

Answer 13

oncogene activation or tumor suppressor gene loss

Question 14

Papillary cancer mutations

Answer 14

RET (proto-oncogene)/PTC rearrangement mutation (20%)

BRAF point mutation:40% (most common)**

p53 inactivation (point mutation)– normally inhibits cell growth and division

Question 15

Follicular thyroid cancer

Answer 15

Ras point mutation (PI3K pathway activation in more aggressive tumors)

Pax8-PPARgamma rearrangement (40-50%)

*look at last slide