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Questions and Answers
What percentage of adults are estimated to have palpable thyroid nodules?
What percentage of adults are estimated to have palpable thyroid nodules?
Why might dominant thyroid nodules be concerning?
Why might dominant thyroid nodules be concerning?
Which of the following is a reason for conducting a fine needle aspiration (FNA) of the thyroid?
Which of the following is a reason for conducting a fine needle aspiration (FNA) of the thyroid?
Which statement best describes the occurrence of thyroid nodules in adults?
Which statement best describes the occurrence of thyroid nodules in adults?
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What is a common characteristic of dominant thyroid nodules?
What is a common characteristic of dominant thyroid nodules?
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Study Notes
FNA Thyroid Lesion
- A Fine-Needle Aspiration (FNA) is used for thyroid lesions
- 4-7% of adults have palpable thyroid nodules.
- Most thyroid nodules are benign, but dominant nodules are suspicious for malignancy.
- Less than 5% of nodules are malignant.
- Clinical features suggesting a benign nodule include:
- Hypothyroidism or hyperthyroidism
- Family history of Hashimoto's thyroiditis
- Sudden increase in size, pain, and tenderness
- Patients with thyroid problems may undergo radionuclide imaging.
- Fluorodeoxyglucose positron emission tomography (FDG-PET) is used to detect thyroid nodules.
- Reduced uptake in a nodule produces a cold nodule.
- Increased uptake produces a hot nodule.
FDG-PET Imaging Results
- Cold nodules - results in the following
- Cystic lesion
- Nodular goiter
- Carcinoma
- Hot nodules: Almost always benign or Hyperthyroidism
National Cancer Institute for Thyroid FNA
- Every palpable thyroid nodule should be considered for FNA.
- Nodules usually larger than 1 cm and any nodule 0.5 cm x 0.5 cm that's clinically significant needs FNA.
- Before FNA, Obtain detailed clinical history, perform a physical examination, and assess serum TSH levels and US.
US Findings
- Lesions greater than 1.0 to 1.5 cm should have FNA unless simple or separated cyst with no solid elements.
- Nodules of any size with suspicious US features should have FNA especially if a solid mass is present in the nodule.
Suspicious US Findings
- Microcalcifications
- Hypoechoic, solid nodules
- Irregular/lobulated margins
- Intra-nodular vascularity
- Nodal metastases or signs of extracapsular spread
US-Guided FNA
- Cost-effective compared to palpation-guided FNA
- Aids in thyroid disease management
- Reduces non-diagnostic and false-negative FNA rates
- Provides informative cyst contents.
Recommended US-Guided FNA Use
- Non-palpable thyroid lesions
- Nodules less than 1 cm in diameter (but suspicious lesions)
- Nodules more than 25% cystic, or those previously biopsied with non-diagnostic results (those requiring further testing)
FNA Techniques
- Ultrasound-guided needle aspiration
- Fix the needle in 95% ethanol
- Smear slides and label them with patient identifiers.
- Centrifuge the sample to separate solid materials and liquid
- Use appropriate media to transport samples
Normal Cells of Thyroid
- Follicular cells produce thyroid hormones.
- Hurthle cells are a metaplastic change in follicular cells, resembling oncocytic cytoplasm
- C cells (parafollicular cells) - typically not seen in normal FNA.
- These cells produce calcitonin, a hormone that counters parathyroid hormone by removing calcium from blood into bones.
Follicular Cell Criteria
- Flat to cuboidal to columnar in shape
- Honeycomb sheets
- Cell borders not prominent
- Abundant cytoplasm with distinct cell borders; sometimes abnormal
- Active cells have more cytoplasm
- Dense and granular cytoplasm in Hürthle cells
- Nuclei do not overlap or crowd each other
Nuclear Criteria of Follicular Cells
- Round to oval
- About the size of a lymphocyte
- Smooth membrane
- Moderate hyperchromasia; not coarse, granular chromatin
- Inconspicuous nucleoli (may be more noticeable in reactive cells)
- Multiple and prominent nucleoli indicative of malignancy
Hurthle Cells
- Essentially non-functional follicular cells
- Packed with mitochondria, becoming oncocytes or Hürthle cells
- Collection of these cells makes a cold nodule on US.
- Thyroglobulin positive.
- Associated with Hashimoto's thyroiditis, Nodular Goiter, Sarcoidosis and Neoplasia
- Abundant dense, granular cytoplasm, with distinct cell borders
- Cytoplasm is purple (MGG) and orange (Pap)
- Nuclei are eccentrically located, with enlarged nuclei common ( up to 2 to 4 times)
- Binucleation - common
- Nucleoli are absent to inconspicuous
- Chromatin varies from fine to coarse
Colloid
- Glycoprotein in the thyroid
- Increased colloid amount indicates a benign condition; a decrease could be associated with neoplasia
- Watery colloid (clear)
- Cracking colloid (fragmented)
- Dense colloid (appears abnormal)
- Colloid in Diff Quik (dark purple or blue)
- Bubble gum colloid
Thyroid Histology
- Subdivided into lobules by connective tissue
- Each lobule contains 30 to 40 follicles, which are the basic functional units.
- Follicles are closed spherical cavities lined with eosinophilic substance (colloid)
- Follicles contain C (parafollicular) cells, which are neurosecretory cells, and are a source of calcitonin
- Best viewed with MGG stain
- Microfollicles and macrofollicles
- Stroma surrounding follicles
TBS Reporting for Thyroid
- Main categories for reporting include non-diagnostic/unsatisfactory, benign, undetermined significance, follicular neoplasm, Hurthle cell type, suspicious for malignancy, and malignant.
FNA Adequacy Criteria: Non-Diagnostic/Unsatisfactory
- Less than 6 groups of 10 cells is inadequate.
- Poorly prepared, stained, or obscured follicular cells.
- Fluid from a cyst only is inadequate.
Non-Diagnostic
- Limited due to cellularity due to a lack of follicular cells.
- Poor fixation/preservation.
- Cyst with blood and macrophages (indicating inflammation)
Benign Thyroid Cytology
- Benign follicular nodule
- Nodular goiter
- Colloid nodules
- Hashimoto's thyroiditis
- Acute thyroiditis
- Granulomatous thyroiditis (thyroiditis with granulomas)
Acute Thyroiditis
- Bacterial or fungal infection (unusual)
- Can occur in young, old, malnourished, or immunocompromised patients.
- Cytology reveals PMNs (polymorphonuclear leukocytes) and macrophages, inflamed debris, rare degenerating follicular cells
Granulomatous Thyroiditis
- Granulomas present
- Lymphocytes, plasma cells and eosinophils are commonly found
- PMNs
- Rare degenerated follicular cells, dark blue to brown paravacuolar granules
- Rare Hürthle cells
- Differential diagnosis: Hashimoto's thyroiditis, anaplastic carcinoma
Chronic Thyroiditis (Hashimoto's Thyroiditis)
- Autoimmune disorder
- More common in women in their 30s and 40s
- Mature lymphocytes and oncocytes/Hürthle cells are present to make the diagnosis
- Macrophages found
- Rare follicular or colloid cells
Hyperthyroidism (Graves' Disease)
- Small numbers of tall, columnar follicular cells
- Enlarged nuclei
- Increased cytoplasm with round vacuoles
- Vacuoles contain colloid (flame or flare cells on stained slides)
- Colloid material stains bright red
Graves' Disease (Cytology)
- Hyperplastic nodules (nodular or diffuse goiter) - one of the most common types of thyroid disease
- Follicular cells in small groups, sheets or macrofollicles
- Colloid
- Macrophages
- Rare PMNs and lymphocytes are common
Nodular Goiter
- Numerous chains of benign follicular cells
- Presence of colloid
Hyperplastic Nodule
- Benign thyroid nodule without any vascular or capsular invasion
Colloid Nodule
- Bilateral/diffuse
- Abundant colloid
- Pink to gray on Papanicolaou smears
- Blue to violet on MGG smears
- Rare follicular cells
- Rare Hürthle cells
- Macrophages
- Rare PMNs and lymphocytes
Follicular Neoplasm
- Cytology (FNA) can't distinguish benign from malignant.
- Numerous monotonous follicular cells
- Micro to mac follicles
- Small clusters, acini or rosette-like formations
- Crowded groups of cells
- Absent to scant colloid
- Increased nuclear size
- Granular to coarse chromatin
FN, Hurthle Cell Type/Hurthle Cell Neoplasm
- Highly unpredictable
- Monomorphic Hürthle cell population
- Discohesive cell pattern
- Transgressing capillaries
- Prominent nucleoli (anisonucleosis)
- Binucleation is common
- Abundant eosinophilic granular cytoplasm
- Scant colloid
Diff Dx of Hurthle Cell Neoplasm
- Papillary carcinoma variants
- Medullary carcinoma
Malignant Papillary Thyroid Carcinoma (PTC)
- Most common malignant neoplasm (80%) of thyroid
- More common in women
- More common in 30 to 50-year-old patients
Papillary Thyroid Carcinoma (PTC) Cytology
- Highly Cellular
- Rare to absent colloid
- 3D clusters of cells
- Single cells
- Papillary groups or microfollicles
- Cells may appear bland in nice flat sheets
Other Cytologic Features of PTC
- May see psammoma bodies
- Variable cytoplasm
- Scant, squamoid, Hurthle-like or vacuolated
- Tend to be cystic
- May see hemosiderin-laden macrophages and MNGC's
PTC Morphology
- Follicular cells enlarge
- Chromatin becomes open (hypochromic)
- Irregular nuclear distribution
- Nuclear grooves
PTC Morphology (contd.)
- Papillary formations
- Psammoma bodies
- Crowded/overlapping nuclei
- Margination of chromatin
- Central clearing
- Nuclear pseudoinclusions
- Nuclear grooves
PTC Morphology (contd.)
- Clearing of chromatin
- Nuclear grooves
- Nuclear pseudoinclusions
PTC Morphology (contd.)
- Anisonucleosis (enlargement of nuclei)
Transgressing Capillaries - PTC
- Only seen in PTC
- Transfer of blood and nutrients to cancer cells
PTC - Psammoma Bodies
- Source of calcification in Ray
Medullary Carcinoma
- Rare (5 to 10% of thyroid cancer)
- Poor prognosis
- Primarily affects adults
- Arises from parafollicular (C-cells)
- C cells produce calcitonin
- Tumor produces amyloid
- Greenish-yellow to orange
- Part of MEN (multiple endocrine neoplasia)
Medullary Carcinoma Cytology
- Arrangement: numerous single cells or loose clusters
- Large cells with variable sizes and shapes
- Abundant eosinophilic cytoplasm (70%)
- Plasmacytoid cell shapes + salt and pepper chromatin
- Absent to scant colloid
- Amyloid present in the background (Congo Red +)
Medullary Carcinoma Nuclear Criteria
- Round to oval nuclei
- Eccentric nuclei location with a fine-to-coarse chromatin
- Spindle nuclei may be seen
- Multinucleate
- Small nucleoli
- Pseudonclusions/intranuclear holes (50%)
Anaplastic Carcinoma (Giant Cell Type)
- Worst prognosis ( < 1 year survival)
- Occurs in patients older than 60
- Two histological types: giant cell and spindle cell
- Large pleomorphic/bizarre cells
- Giant polygonal shapes
- Coarse clumped chromatin
- Irregular nuclear membranes
- Prominent nucleoli
- Necrosis and inflammation are common
- Multinucleated cells are possible
Anaplastic Carcinoma (Spindle Cell Type)
- Small spindle-shaped cells
- Sarcomatoid morphology (like a sarcoma)
- Scant to moderate cytoplasm
- Hyperchromatic nuclei
- Coarse granular chromatin
- Nuclear molding (nuclei may be indented and abnormal)
- Irregular nuclear membranes
Anaplastic Carcinoma (Small Cell Type)
- Questionable origin
- High cellularity
- Small, round to oval cells
- Scant basophilic cytoplasm
- Difficult to distinguish from lymphoma or metastatic small cell carcinoma
Lymphoma
- Rare (less than 2% of thyroid cancers)
- Common in older women, with a history of Hashimoto's thyroiditis
- Similar cytology to Hashimoto's, but without Hürthle cells
- Lymphocytes are malignant
- Hürthle cells are rare or absent
- Monomorphic population of small or large lymphocytes
- Differential: Hashimoto's
Metastatic Carcinoma
- Rare
- Needs patient history, particularly for cancer-related illnesses elsewhere (e.g. lung, breast, kidney)
- Renal carcinoma mimics follicular, and melanoma mimics medullary carcinoma
- Lung carcinoma mimics anaplastic carcinoma
SCC on Thyroid
- Squamous cell carcinoma (SCC) on the thyroid
Small Cell Carcinoma of Lung - Mets to Thyroid (contd.)
- Often appears as capping-molding
Melanoma in Thyroid
- Positive HMP 45 stain
Atypia of Undetermined Significance (FLUS)
- Follicular lesion of undetermined significance/Atypia
- 5 to 10% risk of malignancy
- Cytology not convincingly benign
- Architectural and/or nuclear atypia
- Insufficient for follicular neoplasm or suspicious for malignancy
- Represents a small percentage of FNA results, in samples compromised by blood, poor fixation, or low cellularity
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Description
Test your knowledge on thyroid nodules in adults. This quiz covers key aspects such as prevalence, concerns related to dominant nodules, and the role of fine needle aspiration (FNA). Understand the characteristics and implications of thyroid nodules through engaging questions.