Lec 7 Thyroid goiters Flashcards
What is most common cause of goiter world wide?
endemic iodine deficiency
What are most common causes of goiter in the US?
- multinodular goiter
- autoimmune thyroid disease [hashimotos]
What is a multinodular goiter?
- form of thyroid hyperplasia
- familial
- gradually progressive
Who gets multinodular goiters?
women in middle years of life
What do you see on histology in multinodular goiter?
abundant colloid; follicles of varying size lined by benign follicular epithelium; some fibrosis
How can you confirm diagnosis of toxic multinodular goiter?
radioiodine scan
What percent of thyroid nodules are malignant?
5%
What is epidemiology of thyroid nodules?
female:male 4:1
seen in 4-7% of adult US population
What are 3 most common types of thyroid nodules?
- colloid nodule [multinodular goiter]
- follicular adenoma
- thyroid cancer
What are characteristic appearance of follicular adenomas?
benign neoplasms with well developed capsule around the tumor
What is michael reese series?
of pts irradiated at age < 15
- 39% develop thyroid nodules
11% develop thyroid cancer
may appear decades after radiation
What is best test to see if nodule is cancer?
fine needle aspirate
detects the majority of thyroid cancers
What is most common type of thyroid cancer?
papillary carcinoma
What is prognosis of papillary thyroid carcinoma?
relatively indolent; low mortality in younger patients
What are prognostic factors for low mortality in papillary carcinoma?
- older age
- extrathyroidal tissue invasion
- cervical lymph node met
What are 2 major genes associated with papillary carcinoma? mech?
- BRAF
- RET
both activate MAPK signalling
What is mech of action sorafenib?
kinase inhibitor = target for metastatic thyroid cancer
What type of cancer do you see orphan annie eye cells?
papillary carcinoma
What are two histologic characteristics of papillary carcinoma?
- orphan annie eye cells
- psamomma bodies
- papillary architecture with nuclear pleiomorphism
What is prognosis of follicular carcinoma?
- prone to hematonegous distant met –> lung and bone
- poor prognosis
What do you see histologically in follicular carcinoma?
capsular invasion
What type of thyroid cancer has rapid enlargement that causes dyspnea?
anaplastic carcinoma of thyroid –> invades or compresses trachea
What is prognosis of anaplastic carcinoma?
highly lethal; media survival < 1 yr
invades local structures in neck and has distant mets
Who gets anaplastic carcinoma?
elderly patients
What do you see on histology in anaplastic carcinoma?
- de-differentiated cells
- spindle cell appearance
- lack of features of normal thyroid tissue [no colloid or follicular structures]
What type of thyroid cancer has atypical cells without follicular clusters and elevated calcitonin?
medullary carcinoma of thyroid
Which cells of thyroid make up medullary tumor?
calcitonin secreting C cells
What is genetics/inheritance of medullary carcinoma of thyroid?
- inherited ret oncogen
- MEN type II [with pheochromocytoma and hyperparathyroidism]
What is use of calcitonin in medullary carcinoma?
marker for diagnosis and recurrence
What do you see on histology in medullar carcinoma of thyroid?
amyloid deposits; lack of follicular architecture
