E3 - Thyroid nodules and cancer Flashcards
What are thyroid nodules?
- abnormal growth within the thyroid gland
- 4-7% of the population have palpable nodules
What is the frequency of malignancy in thyroid nodules?
5-10% of solitary cold nodules are malignant
What patient history is taken for thyroid diseases?
- characteristics of the nodule
- other symptoms: hyper/hypo- thyroid; compression
- family history: MEN (multiple endocrine neoplasia)
- neck irradiation
What is the physical examination for thyroids?
- size
- consistency, multiple, solitary
- fixed or mobile
- cervical lymph nodes
What feature cause thyroid cancer suspicion?
- hypodensity
- microcalcification (70% probability of cancer)
- hypervascularization
- solid nodule
- irregular borders
- lack of halo sign
What is TIRADS?
Thyroid Imaging Reporting and Data System
- EU-TIRADS 1: normal
- EU-TIRADS 2: benign
- EU-TIRADS 3: low risk
- EU-TIRADS 4: intermediate risk
- EU-TIRADS 5: high risk
What are the ultrasound features of EU-TIRADS 1?
normal
- no nodules
What are the US features of EU-TIRADS 2?
benign
- pure cyst
- entirely spongiform
What are the US features of EU-TIRADS 3?
low risk
- ovoid, smooth, isoechoic/hyperechoic
- no features of high suspicion
What are the US features of EU-TIRADS 4?
intermediate risk
- ovoid, smooth, mildly hypoechoic
- no features of high suspicion
What are the US features of EU-TIRADS 5?
high risk
At least one of the features of high suspicion:
- irregular shape
- irregular margins
- microcalcification
- marked hypoechogenecity (and solid)
What is the gold standard diagnostic exam for suspicious thyroid nodule?
FNAB: fine needle aspiration biopsy
How is FNAB interpreted for thyroid nodules?
using the Bethesda categories
- insufficient (1-4% risk of malignancy)
- benign (0-3%)
- atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FUS) (5-15%)
- follicular neoplasia (15-30%)
- suspicious for malignancy (60-75%)
- malignant (97-99%)
What is the diagnostic approach for thyroid nodules?
- history and physical exam
- ultrasound
- cytology (10-40% uncertain)
- genetic tests
What is PTC?
- papillary thyroid cancer
- 60-80% of all thyroid malignancies
- most common
What is FTC?
- follicular thyroid cancer
- 10-15% of all thyroid malignancies (second most common)
What are the differentiated thyroid carcinomas?
- papillary (60-80%)
- follicular (10-15%)
Evaluating thyroid nodules using TSH level and US
- elevated TSH: higher risk of malignancy
- low TSH: indication of thyroid scintigraphy
- thyroid US: indicated in patients w/ palpable nodules or suspicion of malignancy
Evaluating thyroid nodules using scintigraphy
cold nodule (hypofunctioning)
- circumscribed area of reduced radioiodine uptake; reduced or no physiologic secretory function
- FNAB and US recommended
hot nodule (hyperfunctioning)
- circumscribed area of increased radioiodine uptake; increased function
- rarely malignant, FNAB not recommended
What are the types of thyroid nodules?
- follicular adenoma
- toxic adenoma
- toxic multinodular goiter
- thyroid cysts
What are the characteristics of follicular adenoma?
- most common type of thyroid adenoma
- slow-growing solitary nodule
- normal TSH w/ US signs of malignancy
- thyroid surgery is always indicated
- in case of follicular cancer: complete thyroidectomy and treatment of thyroid cancer is necessary
What are the characteristics of toxic adenoma?
- third most common cause of hyperthyroidism
- most common in individuals b/w 30-50yrs
- palpable, and usually painless
- symptoms of thyrotoxicosis
- TSH decreased + T3 elevation
- scintigraphy shows solitary hot nodule w/ suppression of rest of the gland
- initial treatment of hyperthyroidism with β-blockers and antithyroid drugs
- definitive treatment: hemithyroidectomy and RAIA (radioactive iodine therapy)
What are the characteristics of multinodular goiter?
- 2nd most common cause of hyperthyroidism
- often in people over 60yrs old, more prevalent in iodine-deficient regions
- painless goiter with multiple palpable nodules
- symptoms of thyrotoxicosis
- TSH decreased and T3 elevated
- multiple hot nodules and some cold nodules can be present
- initial treatment with beta blockers and antithyroid drugs
- definitive treatment: total or near-total thyroidectomy and RAIA
What are the characteristics of thyroid cysts?
- simple cysts are fluid filled nodules lined by benign epithelial cells
- complex cysts are partly solid and partly cystic, carry a 5-10% risk of malignancy
- most commonly due to cystic degeneration of thyroid tissue or involution of an adenoma
- large cyst or extensive hemorrhage can cause compression symptoms (ie. dysphagia, hoarseness)
- same diagnostic tests as for other thyroid nodules
- large or asymptomatic benign cysts are treated with aspiration or surgery
What are the types of thyroid cancers?
- papillary carcinoma (70%)
- follicular carcinoma (20%)
- anaplastic carcinoma (5%)
- medullary carcinoma (2%)
What are the characteristics of papillary carcinoma?
- most common malignant neoplasm of thyroid
- metastases to cervical lymph nodes
- occurs at any age (esp. 30-50yrs), higher risk in case of previous exposure to ionizing radiation
-
morphology
- solitary or multifocal lesions
- well circumscribed and encapsulated or infiltrative
- Orphan Annie eye nuclei: nuclei contain finely dispersed chromatin (optically clear appearance) -
clinical features
- painless mass in the neck (within thyroid or cervical lymph nodes)
- good prognosis
What are the characteristics of follicular carcinoma?
- more common in women, ages 40-60 yrs
- increased incidence in case of dietary iodine deficiency, nodular goiter may predispose to development of neoplasm
-
morphology
- minimally invasive: usually small, encapsulated neoplasms that show invasion only into the tumor capsule; no vascular/lymphatic invasion; excellent prognosis
- widely invasive: invasion through capsule into surrounding thyroid tissue; can replace entire thyroid and invade local structures (displays hematogenous metastases) -
clinical features:
- present mostly as solitary cold thyroid nodules
- tends to metastasize hematogenously to lungs, bone and liver
- treated with surgical excision to have good prognosis
What are the characteristics of medullary carcinoma?
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