Thyroid Neoplasia + Diseases of Parathyroids (Handorf) Flashcards
Thyroid nodules are more likely to be neoplastic when they are:
solitary, in younger patients, in male patients, and in patients with a hx of radiation to head/neck
(Hot/cold) nodules are almost always benign, while (hot/cold) are malignant 10% of the time.
hold
cold
Benign thyroid nodules:
“Colloid” nodules
Follicular adenomas
Cysts
Malignant thyroid nodules:
Papillary carcinoma (75-85%) Follicular carcinoma (10-20%) Medullary carcinoma (5%) Anaplastic carcinoma (<5%)
Rapid and cost effective diagnostic technique for thyroid nodules.
Needle aspiration + cytologic evaluation of aspirated material
How do you distinguish between benign and malignant follicular lesions?
Examine surgically excised tissue for capsular +/- vascular invasion
*cannot distinguish by FNA; cytologic characteristics (nuclear features, mitotic figures, etc) are the same for both benign and malignant follicular lesions
Describe histological characteristics of follicular adenomas.
Solid, trabecular, or follicular pattern with NO microscopic capsular invasion; produces colloid to some extent
What type of thyroid malignancy occurs before 40 y/o? After 40 y/o?
before = papillary and follicular carcinomas
after = medullary and anaplastic tumors
Key factors in the prognosis of thyroid carcinomas?
age and spread beyond capsule at diagnosis
What is the prognosis of medullary carcinoma relative to that of papillary carcinoma?
they are similar
What is the prognosis of follicular carcinoma relative to that of papillary carcinoma?
papillary has a higher 5 and 10 year survival
p = 92% and 87%, compared to f= 74% and 66%
All papillary thyroid lesions are classified as
carcinomas
Describe gross appearance of papillary carcinomas
less circumscribed than benign lesions
Papillary carcinoma in thyroid tends to produce:
lamellar calcified structures known as “psammoma” bodies.
Describe gross appearance of follicular carcinomas
less circumscribed than benign lesions
Histologically, what distinguishes follicular adenoma from follicular carcinoma?
presence of capsular and vascular invasion in carcinoma
What are medullary carcinomas? What is a characteristic symptom?
Tumor of the parafollicular cells (“C cells”)
**these cells are responsible for producing calcitonin, so patients present with hypocalcemia
Describe gross/histological characteristics of medullary carcinomas
solitary or multiple/bilateral
typically produce amyloid
80% of medullary carcinomas are ______; the rest are associated with:
sporadic
MEN II or non-MEN familial
What is the prognosis of Anaplastic Carcinoma?
“terrible”–typically invade locally and metastasize widely
Mean age of Anaplastic Carcinoma?
65
What are common disorders associated with anaplastic carcinoma?
- -history of thyroid disease (goiter or differentiated carcinoma)
- -20-30% have concurrent differentiated carcinoma (often papillary)
Theorized that anaplastic carcinoma develops in the context of:
other tumors with loss of p53 tumor suppressor gene
What type of lymphomas are most commonly malignant thyroid tumors?
B-cell lineage
What are symptoms of thyroid lymphomas?
- rapidly enlarging goiter
2. disease limited to thyroid (~50% of patients)
Known risk factors of thyroid lymphomas?
Pre-existing chronic autoimmune (Hashimoto’s) thyroiditis
What are common characteristics of small cell carcinoma of the thyroid?
- -highly malignant
- -usually metastatic at time of initial diagnosis
What types of thyroid carcinoma may develop in struma ovarii?
- follicular carcinoma
- papillary carcinoma
- very poorly differentiated and difficult to classify
What was responsible for thyroid malignancies in Chernobyl?
radioactive materials, most notably I-131 (half-life of 8 days), Cs-134 (half-life of 2 years), and Cs-137 (half-life of 30 years)
The 2 inferior parathyroids develop from:
third branchial pouch (also gives rise to thymus)
The 2 superior parathyroids develop from:
fourth branchial pouch
Normally, the four parathyroids are located:
posterior to the thyroid at the upper and lower poles
Most common disorder of parathyroid
Parathyroid adenoma
How does parathyroid adenoma affect the parathyroid?
- -gland increases in size
- -PTH produced in excess with resultant hypercalcemia
How are parathyroid adenomas found?
routine blood tests have elevated blood calcium and PTH levels
Clinical triad of parathyroid adenomas
“Moans, bones, and stones”
- depression (+ muscle weakness)
- bone density diminished
- kidney stones
Pathologically, parathyroid adenomas are distinguished by:
- larger than normal
2. lacking in usual complement of fat seen in normal parathyroids
Parathyroid hyperplasia is defined as:
absolute increase in the mass of the parenchymal cells of the parathyroid gland, usually involving all of the glands
Majority of cases of parathyroid hyperplasia are secondary to:
hyperplasia of chief cells
What are presenting symptoms of parathyroid hyperplasia?
increase in serum calcium (due to increased PTH production)
If all or most of the parathyroid glands are enlarged, a diagnosis of ______ is likely.
hyperplasia
If only one parathyroid gland is enlarged, a diagnosis of _____ is favored.
adenoma
