Thyroid Pathology Flashcards
2 patterns of thyroid enlargement?
Nodular or diffuse.
What’s an oncocytic / Hurthle cell? Where is it seen?
It’s a metaplastic follicular cell. Looks a little abnormal… but not that different.
Seen in both benign and malignant lesions.
What is papillary growth in the context of the thyroid?
Follicular cells proliferate and grow into the lumen.
VEGF promotes vascularization of the stalk.
Are multiple nodules more often benign?
Yes, but multiple nodules doesn’t rule out cancer.
Two main causes of diffuse thyroid enlargement?
Diffuse toxic goiter (Graves’ disease).
Chronic autoimmune lymphocytosis (Hashimoto’s thyroiditis).
(tumors are a rare cause of diffuse enlargement)
What does Graves’ disease thyroid look like grossly?
Symmetric.
Red with vascularization.
Shiny from colloid.
How does the lymphocyte infiltration contrast histologically between Graves’ and autoimmune lymphocytosis?
Graves’ - more focal in stroma.
Hashimoto’s - lymphocytes everywhere.
Which will have more metaplasia: Graves’ or Hashimoto’s?
Hashimoto’s will have more oncocytic / Hurthle’s cells..
4 types of non-toxic nodular goiter?
Endemic - iodine deficiency.
Sporadic
Chemically-induced
Metabolic defects (“dyshormonogenetic” -rare)
What’s the key description of histology of non-toxic nodular thyroids?
Heterogenous - variable within same gland.
What’s the most common thyroid cancer?
Well-differentiated thyroid carcinoma.
What makes a thyroid carcinoma “well-differentiated”?
It still takes up iodine (usefully, radioactive iodine for scans and therapy)
What do follicular adenoma look like, grossly? Histologically?
Well-circumscribed.
Encapsulated.
(benign)
Histologically: Looks benign. No invasion.
Are the majority of thyroid carcinomas well-differentiated?
Yes. Which means they respond well to radio-ablative therapy.
What’s the most well-established causal factor for thyroid carcinoma?
Exposure to radiation - e.g. Chernobyl’s radioactive iodine fallout.
What mutations causing thyroid carcinoma does radiation tend to cause?
Ret oncogene rearrangements
there’s a list of usual-suspect oncogenes… BRAF, RAS, p53, APC…
What happens in Ret oncogene rearrangments leading to (papillary) thyroid caricinoma?
Fusion with another gene such that Ret’s tyrosine kinase domain becomes overactive -> growth. (called “Ret/PTC”)
What are the 2 most common forms of well-differentiated thyroid carcinoma?
Papillary carcinoma
Follicular carcinoma
How does papillary thyroid carcinoma (PTC) spread?
Via lymphatics.
How is diagnosis of PTC made? Can it be diagnosed with fine needle aspiration (FNA)?
Nuclear features! - not all the different morphological subtypes!
Yes, it can be diagnosed with FNA.
Nuclear features of PTC?
Grooves, inclusions, chromatin clearing, etc.
Does all PTC have papillary formations?
No. It’s poorly named.
There are severe growth pattern variants (papillary, follicular, tall cells)… but the diagnosis is made based on nuclei.
10 year survival with PTC?
90% - pretty good.
What’s a notable sex-based difference in thyroid carcinoma?
Most thyroid things more common in women, but when you see a solitary thyroid nodule, it has a 60% of being malignant.
Different in epidemiology between follicular and papillary thyroid carcinoma?
Papillary - more in iodine-sufficient regions.
Follicular - more in iodine-deficient regions.
How does follicular carcinoma behave?
It’s invasive, and spreads hemotogenously.
How is diagnosis of follicular carcinoma made? Can it be made with FNA?
Diagnosis is made based on invasion of capsule or blood vessels.
Diagnosis can’t be made by FNA.
Grossly, what does follicular carcinoma always look like?
Follicular carcinoma always presents as a solitary nodule.
What do you call a carcinoma of C-cells?
Thyroid medullary carcinoma.
What are 3 different types of thyroid medullary carcinoma?
C-cell derived.
Familial syndrome. (esp. MEN2)
Sporadic.
What’s a germ-line mutation that can predispose to medullary carcinoma?
Mutation in Ret-oncogene.
Prognosis of medullary carcinoma at 5 years?
50%
What do you see in medullary carcinoma histology, notably?
Amyloid deposition… forming “tumor nests.”
What is one source of amyloid in medullary carcinoma?
What is the stain for it?
Pro-calcitonin being spewed out by carcinoma cells.
Congo-red is stain for amyloid.
What product to medullary carcinomas often secrete? How do you detect it?
Calcinoma
Can do immunostaining on tissue, or test serum levels.
What’s the worst kind of thyroid cancer? Life expectancy at diagnosis?
Anaplastic carcinoma.
Death in 6-8 months.
Anaplastic carcinoma’s typical clinical scenario?
Person older than 60 with symptoms from carcinoma invading / compressing structures in the neck.
Does anaplastic carcinoma produce thyroglobulin?
No, the cells are just ugly and non-functional.
