Thyroid Path Flashcards
Describe an oncocytic cell: histological appearance and function
Metaplastic follicular cell with pink cytoplasm (lots of mitochondria) , round nucleus, round nucleolus
Describe the appearance and function of C-cells
C-cells produce calcitonin
Located at lateral aspect of thyroid; rarely seen in regular histology until hyperplastic
Factors in histology: enlargement
Diffuse vs. nodular process– is nodule solitary or dominant? capsulated? Smooth or irregular borders?
Factors in histology: lesion architecture
Describes cell growth pattern:
Follicles, papillae, solid, trabecular
Other features of lesion that are important in thyroid lesion
fibrosis, calcification, amyloid (medullary carcinoma)
Describe factors in tumor cell cytology
Cell size
Cytoplasm: indistinct or oncocytic
Nuclear morphology: shape and presence of folds/grooves or inclusions
Nucleoli: prominent; placement in nucleus
Which types of enlargement are more likely to be malignant? Benign?
Nodular:
solitary=malignant
multiple=benign
diffuse: benign due to Graves or Hashimoto’s; can rarely be tumors
Describe the gross pathology of Grave’s disease (4)
Symmetric and diffuse enlargement of thyroid gland
Red/brown cut surface
Decreased colloid
Increased vascularity
Describe the histology of Grave’s disease (2)
Papillary hyperplasia (increased follicles and irregular stroma) Lymphocytic infiltration in stroma
Describe the gross pathology of Hashimoto’s thyroiditis: (2)
diffusely enlarged gland
Lobulated cut surface (white)
Describe the histological appearance of Hashimoto’s thyroiditis (3)
Follicular atrophy
Lymphocytic infiltration throughout gland
Oncocytic metaplasia
Prevalence of thyroid nodules
4-7% of US population
What are the types of non-toxic nodular goiter? (4)
Endemic goiter (iodine deficiency)
Sporadic goiter
Chemically induced goiter
Dyshormonogenetic goiter
Gross pathology of non-toxic nodular goiter (big list)
Heterogenous: Firm, diffusely enlarged Cut surface is shiny and amber---increased colloid accumulation Asymmetric enlargement Multinodular Hemorrhage Calcification Fibrosis Cystic degeneration
Describe the histological appearance of non-toxic nodular goiter
Variable sized follicles with columnar epithelium that can be tall or flattened
Papillary hyperplasia
Fibrosis (follicles outgrow blood supply)
Describe the gross appearance of a follicular adenoma (3)
Solitary
Well circumscribed/encapsulated
Histological appearance of follicular adenoma (3)
Encapsulated nodule
Follicular, solid, trabecular growth pattern
No invasion
What is the epidemiology of malignant epithelial tumors of thyroid?
Uncommon– 1-2% of all cancers
More common in females
How do most thyroid tumors behave?
indolent
What is pathogenesis of follicular cell
irradiation during childhood– causes papillary carcinoma due to ret oncogene rearrangements
What are mutations of thyroid neoplasms? (5)
Ret/PTC rearrangement RAS BRAF p53 Adenomatous polyposis coli gene (APC)
Describe RET/PTC rearrangement.
In which thyroid malignancy is this seen?
Inversion on chromosome 10 leads to over activation of tyrosine kinase of Ret
Seen in 60-80% of papillary thyroid carcinomas, especially due to irradiation
What is cell of origin in epithelial neoplasms? What do they produce?
What are the two epithelial neoplasms?
Follicular cells, which produce thyroglobulin
Neoplasms are follicular cell carcinoma and papillary thyroid carcinoma
Describe the epidemiology of papillary thyroid carcinoma
Most common type of thyroid cancer: 80% of thyroid cancers in non-endemic goiter regions
More common in women
What are the pathological features for diagnosis in papillary thyroid carcinoma?
Nucleus
Nuclear features: elongation, chromatin clearing, membrane thickening, grooves and inclusions
What are the growth patterns of papillary thyroid carcinomas?
Papillary formations (core with stuff around) Follicular variant-- colloid Tall cells
What is gross pathology of papillary thyroid carcinoma?
Cystic with mound of tumor cells
Describe the clinical behavior of papillary thyroid carcinoma?
Aggressive– older age, male, large size, tall cell variant, distant metastases
Describe the epidemiology of follicular carcinoma
5% of all thyroid carcinomas in US
Incidence increase with age
Common in iodide deficient regions
Describe important features of follicular carcinoma (3)
Encapsulated tumor that invades
Hematogenous spread to brain, lungs and bone
Prognosis is dependent upon extent of invasion
Describe the histological pathology of follicular carcinoma
Capsular but with vascular invasion. All about vascular invasion
Name differences between papillary carcinoma and follicular carcinoma (3)
- Diagnosis based on nuclear morphology vs. vascular invasion
- Spread via lymphatics vs. blood vessels
- Presentation as multiple tumors vs. single tumor nodule
From which cell type does medullary carcinoma originate?
What are causes? (2)
Originates from C-cells so produces calcitonin
It can arise from MEN2 disorders or be sporadic
What is the pathogenesis of medullary carcinoma (what mutation is involved?)
What is prognosis?
Germ line mutation of ret-oncogene
Secretes calcitonin, other hormones
Prognosis is 50% at 5 years
Describe the histological appearance of medullary carcinoma? (2)
Nest-like pattern (since its neuroendocrine–think theochromyocytomas!)
Stains for amyloid and calcitonin
What is the prognosis for anaplastic carcinoma? Which patients are more likely to get this?
Prognosis: fatal– invade into surrounding neck structures
Constitutes 5% all thyroid malignancies
What is epidemiology of anaplastic carcinoma? What is anapestic carcinoma usually preceded by?
Women>60 years of age
Preceded by a history of goiter
Can also result from de-differentiation of other thyroid malignancy
Describe the histological appearance of anaplastic carcinoma .
What does it stain for?
Pleomorphic tumor cells– spindle cells and multinucleated giant cells
Does not stain for thyroglobulin, calcitonin
