Thyroid Histology 177

Question 1

When during gestation does the thyroid gland develop?

Answer 1

day 24 of gestation

first endocrine gland to develop

Question 2

What embryological structure does the thyroid gland develop from?

Answer 2

originates from a proliferation of endodermal epithelial cells on the median surface of the pharyngeal floor (from the first pharyngeal arch)

Question 3

Describe the descent of the thyroid?

Answer 3

it descends and is connected to the tongue by the thyroglossal duct

becomes obliterated during weeks 7-10

Question 4

What are Hurthle cells?

Answer 4

epithelial cells with abundant, granular cytoplasm that are rich in mitochondria and may be metaplastic or neoplastic in the thyroid

Question 5

What are C-cells derived from?

Answer 5

derived from neural crest cells

Question 6

What are the findings on fine needle aspiration biopsy of hyperplastic/adenomatous/adenomatoid nodules?

Answer 6

follicular/metaplastic hurthle cells and variable degenerative changes

Question 7

What is the gross pathology of Hashimoto thyroiditis? Microscopic?

Answer 7

gross: usually diffusely enlarged
microscopic: extensive infiltration of parenchyma by a mononuclear inflammatory infiltrate of small lymphocytes, plasma cells, and germinal centers with atrophic follicles lined by Hurthle cells

Question 8

What are the FNA biopsy findings of Hashimoto’s thyroiditis?

Answer 8

Hurthle cells in conjunction with heterogenous lymphocytes

Question 9

What is the most common congenital anomaly of the thyroid?

Answer 9

a thyroglossal duct cyst

midline, spherical cystic mass that moves with swallowing

Question 10

What is the triad of clinical findings of Graves’ disease?

Answer 10

diffuse hyperplasia of the thyroid, ophthalmopathy, and dermatology

Question 11

What is the treatment of thyroglossal duct cysts?

Answer 11

removal of the cyst and part of the hyoid bone

sistrunk procedure

Question 12

What genetic mutations can be associated with thyroid adenomas?

Answer 12

mutations of RAS or PIK3CA

Question 13

What is the gross pathology of thyroid adenomas?

Answer 13

encapsulated masses with areas of hemorrhage, fibrosis, calcification, and cystic changes

Question 14

What are the major subtypes of thyroid carcinoma?

Answer 14

papillary carcinoma, follicular carcinoma, anaplastic (undifferentiated) carcinoma, medullary carcinoma

Question 15

What are the macroscopic and microscopic findings of papillary carciomas of the thyroid?

Answer 15

macroscopic: fibrosis, calcification (psammoma bodies), cystic changes
microscopic: oval to elongated shape, finely dispersed chromatin, optically clear or empty appearance (orphan annie eye nuclei), intranuclear inclusions

Question 16

What genetic changes are associated with papillary carcinomas?

Answer 16

activation of the MAP kinase pathway

• rearrangements of RET or NTRK1
• activating point mutations in BRAF

Question 17

Follicular carcinomas are more frequent in areas with iodine (sufficiency or deficiency).

Answer 17

Follicular carcinomas are more frequent in areas with iodine deficiency.

Question 18

What are the microscopic characteristics of follicular carcinoma?

Answer 18

uniform cells forming small follicles containing colloid or may have nests of cells without colloid

Question 19

What is the clinical course of follicular carcinoma?

Answer 19

slowly enlarging painless, nodules that don’t often invade lymphatics

Question 20

What is the treatment for follicular carcinomas?

Answer 20

total thyroidectomy followed by radioactive iodine

Question 21

What are non-invasive follicular thyroid neoplasm with papillary-like nuclear features?

Answer 21

an encapsulated follicular variant of PTC that is minimally invasive characterized by encapsulation, follicular growth pattern, and some features of papillary carcinoma

Question 22

What is the clinical presentation of anaplastic carcinomas?

Answer 22

rapidly enlarging neck masses, aggressive, high mortality

Question 23

What is the microscopic morphology of anaplastic carcinoma?

Answer 23

1) pleomorphic giant cells
2) spindle cells with sarcomatous appearance
3) mixed spindle and giant cells

Question 24

What cells form thyroid medullary carcinomas?

Answer 24

C cell derived neuroendocrine neoplasms

• sometimes they secrete hormones like serotonin, ACTH, and VIP*
• can be sporadic or associated with MEN syndromes or familial tumors*

Question 25

What is the microscopic morphology of medullary carcinoma?

Answer 25

polygonal to spindle shaped cells that can form nests, trabeculae, or follicles

acellular amyloid deposits in adjacent stroma

Question 26

What types of lymphomas are associated with Hashimoto’s thyroiditis?

Answer 26

non-hodgkin and B cell type lymphomas

Question 27

What is the most important test in the diagnosis of thyroid nodules?

Answer 27

fine needle aspiration biopsy (FNA)

Question 28

What is this?

Answer 28

papillary adenocarcinoma

• atypical nuclear morphology*
• hypochromasia, nuclear grooves, intranuclear inclusions, ovoid nucleuis, “orphan annie eye” nuclei*