Thyroid Nodules Assessment Quiz

FNA Thyroid Lesion

• This presentation covers fine-needle aspiration (FNA) of thyroid lesions.
• The procedure is used to assess thyroid nodules for malignancy.
• Thyroid nodules are common, affecting 4-7% of adults.
• Dominant nodules are often suspicious, with less than 5% being malignant.
• Benign features include hypo/hyperthyroidism, family history of thyroiditis, and a sudden increase in size, pain, and tenderness.

Indications for FNA

• Patients with thyroid concerns may undergo radionuclide imaging.
• Fluorodeoxyglucose positron emission tomography (FDG-PET) scans can be employed to identify thyroid nodules.
• Reduced FDG-PET uptake signifies 'cold' nodules, possibly cystic or cancerous.
• Increased FDG-PET uptake results in 'hot' nodules, almost always benign, or indicative of hyperthyroidism.

FDG-PET Imaging Results

• Cold nodules:
  • Cystic
  • Nodular goiter
  • Carcinoma
• Hot nodules:
  • Almost always benign
  • Hyperthyroidism

National Cancer Institute Criteria for Thyroid FNA

• Palpable nodules are ideal candidates for FNA.
• Nodules exceeding 1 cm, or 0.5 cm x 1 cm are typically significant enough to warrant FNA.
• Pre-FNA assessments include clinical history, physical exam, serum TSH (thyroid-stimulating hormone), and ultrasound (US) imaging.

US Findings

• Lesions exceeding 1.0 to 1.5 cm usually warrant FNA unless they are simple cysts.
• A nodule of any size showing suspicious US features should undergo FNA, especially if it contains a solid mass.

Suspicious US Findings

• Microcalcifications
• Hypoechoic, solid nodules
• Irregular/lobulated margins
• Intra-nodular vascularity
• Nodal metastases or extracapsular spread

US-Guided FNA

• US-guided FNA is preferred to palpation-guided procedures.
• It reduces costs and rates of non-diagnostic and false-negative FNA results.
• It offers precise information on cyst fluid content.

FNA Techniques

• The needle is introduced into the nodule via US guidance.
• Samples are preserved with 95% ethanol.
• A centrifuged preparation is made; then, cell blocks are created for microscopy.
• A specific number of needle passes is needed for an adequate sample, varying from 2-5, depending on findings.
• Recommended needle gauge is 25 to 27.

Normal Thyroid Cells

• Follicular cells produce thyroid hormones.
• Hurthle cells are metaplastic follicular cells, resembling oncocytic cytoplasm.
• C-cells (parafollicular cells) are not typically observed in routine FNA.
• They produce calcitonin, a calcium-regulating hormone.

Follicular Cell Criteria

• Shape: Flat to cuboidal to columnar.
• Cell borders: Not prominent.
• Cytoplasm in active cells: More plentiful than in inactive cells
• Cytoplasm in inactive cells: Dense and granular.
• Nuclei: Do not crowd or overlap with one another.

Nuclear Criteria of Follicular Cells

• Shape: Round to oval.
• Size: About the size of a lymphocyte.
• Membrane: Smooth.
• Chromatin: Granular but not coarse.
• Hyperchromasia: Moderate.
• Nucleoli: Inconspicuous.

Hürthle Cells

• Essentially non-functional follicular cells.
• Become packed with mitochondria.
• Collection on US can be cold nodule.
• Positive for thyroglobulin.
• Associated with Hashimoto's thyroiditis, nodular goiter, sarcoidosis, and neoplasia.

Cytology of Hürthle Cells

• Cytoplasm: Abundant, dense, and granular.
• Cell borders: Polygonal with distinct borders.
• Orange to blue cytoplasm (Pap stain).
• Nuclei: Eccentric.
• Enlarged nuclei (2-4 times).
• Binucleation is common.
• Chromatin: Fine to coarse.

Colloid

• Glycoprotein of the thyroid.
• Increased colloid abundance usually indicates a benign condition.
• Decreased colloid amount can indicate possible neoplasia.

Different Appearances of Colloid

• Watery colloid
• Cracking colloid
• Dense colloid (can be abnormal)
• Colloid in Diff Quik
• Bubble gum colloid

Thyroid Histology

• Lobules of the thyroid are separated by connective tissue.
• Follicles (30-40 per lobule) are the functional units.
• Spherical cavities lined with eosinophilic colloid.
• Parafollicular cells (C cells) are also present
• Neurosecretory cells are the source of calcitonin.
• MGG stain is suitable for visualization.

TBS Reporting for Thyroid

• Categorizes FNA results according to diagnostic or unsatisfactory results.
• Grades include benign, undetermined significance, follicular neoplasm, suspicious for malignancy, and malignancy.

FNA Adequacy Criteria (Non-Diagnostic/Unsatisfactory)

• Insufficient cell counts (less than 6 groups of 10 cells),
• Inadequate sample preparation/staining.

Non-Diagnostic Cases

• Limited cellularity.
• Lack of follicular cells.
• Poor fixation or preservation.

Benign Thyroid Cytology

• Includes follicular nodule, nodular goiter, colloid nodules, Hashimoto's thyroiditis, acute thyroiditis, granulomatous thyroiditis.

Acute Thyroiditis

• May be due to bacterial or fungal infections.
• Patients: Young, old, malnourished, immunosuppressed individuals.
• FNA cytology: PMNs (polymorphonuclear leukocytes), macrophages, inflammatory debris potentially seen.

Granulomatous Thyroiditis

• Granulomas, lymphocytes, plasma cells, eosinophils, and PMNs.
• Degenerative follicular cells and rare Hürthle cells are potential findings.

Chronic Thyroiditis (Hashimoto's)

• An autoimmune disorder.
• Mostly seen in females.
• FNA cytology: Mature lymphocytes and oncocytes/Hürthle cells.

Hyperthyroidism (Grave's Disease)

• Small numbers of tall, columnar follicular cells.
• Enlarged nuclei.
• Vacuolated cytoplasm with colloid.
• Colloid stains intensely red.

Graves Disease

• Diffuse non-toxic goiter.
• FNA cytology: Follicular cells in small groups, sheets, or macrofollicles; colloid, macrophages, rare PMNs and lymphocytes.

Nodular Goiter

• FNA cytology: Numerous follicular cells and colloid.

Hyperplastic Nodules

• Benign, without capsular invasion.

Colloid Nodule

• Bilateral and diffuse.
• Abundant colloid.
• Pink to gray on Pap stains, blue to violet on MGG stains.
• Rare follicular/Hürthle cells.
• Macrophages and lymphocytes are possible.

Follicular Neoplasm

• Unable to distinguish between benign and malignant.
• Numerous monotonous follicular cells, micro to macro follicles, small clusters, acini, rosette-like formations are observed.

FN, Hürthle Cell Type/Hürthle Cell Neoplasm

• Highly unpredictable (Hashimoto's thyroiditis, Papillary Thyroid Carcinoma Variants, Medullary Carcinoma are possible differentials).

Diffuse Papillary Thyroid Carcinoma (PTC)

• Most common type of thyroid malignancy accounting for 80% of cases in females.
• Occurring between the ages of 30 and 50.
• Arrangement is highly cellular.
• Colloid is very rare to absent.
• Histological features include 3D cell clusters, single cells, and papillary microfollicle groups.
• Nuclear atypia is required for diagnosis.
• Additional features might include psammoma bodies, variable cytoplasm, and Hurthle-like or vacuolated morphologies.

Medullary Carcinoma

• A rare type of thyroid cancer (5-10% of total cases).
• Originates from parafollicular C cells.
• Produces calcitonin, with tumors displaying amyloid deposits (greenish-yellow to orange).

Anaplastic Carcinoma

• Extremely aggressive, with a very poor prognosis (1-year survival).
• Two main histological types: Giant cell and spindle cell.
• Giant cell type exhibits large, pleomorphic, bizarre cells, coarse clumped chromatin, and prominent nucleoli.
• Spindle cell type presents with small spindle-shaped cells, scant cytoplasm, coarse chromatin, and visible nuclear molding. (Sarcomatoid)
• Small cell type is characterized by highly cellular, often questionable origin, small, round-to-oval cells, and scant basophilic cytoplasm.

Lymphoma (of Thyroid)

• Uncommon (less than 2% of thyroid cancers).
• Commonly involves older women.
• Can mimic Hashimoto's Thyroiditis (absence of Hurthle cells).
• Characterized by the presence of a monomorphic population of small or large lymphocytes (frequently with little-to-no nuclear atypia).

Metastatic Carcinoma

• Can originate from various primary sites (renal, lung, melanoma).

Squamous Cell Carcinoma (SCC)

• A possible metastasis from another primary site.

Small Cell Carcinoma (of Lung)

• Potential metastasis of small cell carcinoma.
• Cytologically, may display "capping and molding."

Melanoma

• Potentially metastasized from another primary site (positive HMP45 staining).

Atypia of Undetermined Significance (FLUS)

• Difficult to definitively assess as benign or malignant.
• Cytological findings are not straightforwardly benign or malignant.
• Characterized by architectural and nuclear atypia but less severe compared to a definitive neoplasm.
• FNA results must represent less than 7% of total cases.

Test your knowledge about thyroid nodules, their prevalence, and clinical evaluations. This quiz covers key aspects of identifying and understanding the significance of palpable thyroid nodules in adults. Explore the reasons behind the suspicion of dominant nodules and the role of fine needle aspiration (FNA) in diagnosis.