Thyroid Nodules Flashcards Preview

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Flashcards in Thyroid Nodules Deck (15):
1

How common are thyroid nodules?

nearly 60%
-risk of cancer in a thyroid nodule is small (10-15%), but not insignif

2

Thyroid neoplasms

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

3

Thyroid adenoma

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

4

Follicular/Hurthle cell carcinoma

two types:
minimally invasive (vascular or capsular invasion)

widely invasive: more extensive invasion

5

Papillary carcinoma

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

6

Anaplastic carcinoma of thyroid gland

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

7

Medullary carcinoma

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 +

8

Lymphomas

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

9

Clinical Eval

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

10

Approach to pt w/ thyroid nodules

**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

11

Papillary carcinoma of thyroid cytologic features

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

12

Bethesda system

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

13

tumors result from

oncogene activation or tumor suppressor gene loss

14

Papillary cancer mutations

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

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

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

15

Follicular thyroid cancer

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

Pax8-PPARgamma rearrangement (40-50%)

*look at last slide