Thyroid Pathology Quiz

The Neck - Thyroid and Non-Thyroid Pathology and Interventions

• Topic is related to the neck, specifically thyroid and non-thyroid conditions and interventions.

Thyroid Gland Pathology

• Congenital Abnormalities:

  • Agenesis/Aplasia: Absence of the thyroid gland.
  • Ectopic thyroid: Thyroid tissue in an abnormal location.
  • Hypoplasia: Underdeveloped thyroid gland.
  • Congenital Hypothyroidism: Lack of thyroid hormone production.
  • Congenital cysts: Inherited cysts in the thyroid.

• Nodular Thyroid Disease:

  • Benign and malignant nodules.
  • Hyperplasia, adenomas, carcinomas, metastases (spread to other tissues)

• Diffuse Thyroid Disease:

  • Thyroiditis: Inflammation of the thyroid gland.
  • Grave's disease: Autoimmune disorder causing hyperthyroidism.
  • Multinodular goitre: Enlarged thyroid gland with multiple nodules.

Thyroid Lab/Imaging Tests

• Thyroid:
  • T3 and T4 hormone levels: Increased (hyperthyroidism) or decreased (hypothyroidism)
  • TSH (thyroid-stimulating hormone): Indicates thyroid or pituitary dysfunction
• Blood work: Measures thyroid and other hormones, response to treatment.
• Thyroid Scan: Diagnoses overactive or underactive thyroid gland; assesses risk of malignancy.
• Nuclear Medicine (Scintigraphy): Assesses thyroid function by measuring uptake of radioactive iodine by thyroid tissue.

Congenital Abnormalities (Specific)

• Thyroid Agenesis/Aplasia: Complete absent thyroid gland or hemi-agenesis (one lobe missing).
• Ectopic Thyroid: Abnormal tissue location, lingual or suprahyoid.
• Thyroid Hypoplasia: Partial or complete underdeveloped thyroid gland.
• Congenital Hypothyroidism: Variable severity and more common in females.
• Congenital Cysts: Rare, often part of larger thyroid masses.

Nodular Thyroid Disease (details)

• Can present with a palpable abnormality or discovered incidentally.
• Happens in 4%-7% of adults, more common in females.
• Etiologies:
  • Benign: Focal thyroid hyperplasia, benign follicular adenomas.
  • Malignant: Thyroid carcinoma (papillary, follicular, medullary, anaplastic, lymphoma, metastases).

Benign vs Malignant Thyroid Nodules

• Management is controversial, as thyroid cancer is rare compared to common nodules.
• "Dominant nodule" is frequently aspirated for assessment, but this value is not indicative.
• Presence of multiple abnormal findings increases malignancy risk.

Sonographic Appearance (Tables)

• Detailed table describing malignant and benign thyroid nodules' sonographic characteristics (internal contents, echogenicity, shape, margins, calcification pattern, peripheral halo, blood flow, and elastography patterns)

ACR TI-RADS

• System to categorize thyroid nodules on ultrasound findings (composition, echogenicity, shape, margins, and echogenic foci) and provide a risk assessment. This categorizes results from 1-7.

Internal Contents/Composition, Echogenicity, Shape, and Margins

• Explanations and visual examples of scores 0, 1, 2, 3 for the four parameters in characterizing nodules on ultrasound.

Blood Flow Pattern

• Blood flow doesn't affect scoring using TIRADS criteria.

Thyroid Imaging Reporting and Data System (TIRADS)

• Six categories for classifying thyroid nodules based on ultrasound findings (1-Normal, 2-Benign, 3-Probably Benign, 4-Suspicious, 5-Probably Malignant, 6-Biopsy-Proven Malignant).

Focal Thyroid Hyperplasia

• AKA thyroid nodule, benign, focal overgrowth of thyroid tissue, most common cause of nodular disease (80%), females > males, peak age 35-50. -May be hereditary or caused by iodine deficiency.
• Lab tests can show decreased, increased or normal lab test function.

Thyroid Hyperplasia (Nodule)

• Sonographic Appearance: Usually single, isoechoic(most common), may be hyperechoic if large, common cystic degeneration (simple cyst appearance, not true cysts), anechoic fluid = colloid (colloic cysts), Echogenic fluid = hemorrhage, honeycomb appearance.
  • May see hypoechoic halo, peri-nodular vascularity, thin septations, echogenic foci with comet-tail, calcifications (coarse or egg-shell), solid papillary projections, and internal vascularity

Papillary Carcinoma

• Most common thyroid carcinoma (75-90%), 2 peaks (30s and 70s), least aggressive, spread is lymphatic, metastases to cervical lymph nodes (most common) or mediastinum and lung (less commonly).
  • Sonographic Appearance: Solid hypoechoic mass, microcalcifications, tiny punctate echogenic foci, with or without shadowing, hypervascularity (90%).

Follicular Carcinoma

• 2nd most common,
• 5-15% of thyroid carcinomas, two types (minimally and widely-invasive).
• Spread is hematogenous, metastases to: bone, lung, brain, liver.
• Sonographic Appearance: solid mass, single or multiple, variable echogenicity, hypoechoic, hyperechoic or isoechoic, peripheral hypoechoic halo, thick and irregular compression of adjacent tissue, peripheral vascularity, possible internal vascularity (spoke wheel pattern).

Follicular Adenoma vs Follicular Carcinoma

• Sonographic appearance is similar, especially for small sizes.
• Diagnoses require histology.

Medullary Carcinoma

• 5% of thyroid carcinomas, derived from parafollicular (C) cells, secretes calcitonin.
• More aggressive than papillary and follicular. Metastases are to cervical lymph nodes.
• Sonographic appearance: solid, hypoechoic mass, coarse calcifications (can have shadowing), cervical lymphadenopathy (also can have calcifications), lesions can be all over the body.

Anaplastic Carcinoma

• Least common, 2% of thyroid cancers. Elderly population, associated with papillary or follicular carcinoma.
• Most aggressive type, 5 year survival rate >95%. Spread via local invasion into muscles and vessels of the neck.
• Sonographic Appearance: Hypoechoic, rapidly enlarging, encases or invades vessels and muscles; extra imaging (CT or MRI) may be needed because of the large size.

Thyroid Lymphoma

• Lymphoma affects any organ, usually non-Hodgkin's type.
• Prognosis and aggressiveness vary with stage of diagnosis.
• Frequently fast-growing, causing difficulty breathing and swallowing.
• Sonographic Appearance: Extremely hypoechoic, lobulated mass, may have cystic necrosis of the lesion, encasing adjacent structures, and hypovascularity.

Thyroid Metastases

• Malignant spread from another primary tumor to the thyroid. It's rare.
• Commonly occurs during later stages of the primary disease.
• Primary sites: melanoma, breast, and renal cell carcinoma (RCC).
• Sonographic Appearance: Solitary, solid nodule, well-circumscribed, hypoechoic, no calcifications common.

Diffuse Thyroid Disease (overview)

• Thyroiditis, Grave's disease, multinodular goiter. Characterized by diffuse gland enlargement, may be symmetric or asymmetric, with or without focal nodules. The isthmus thickness is measured by ultrasound and should be greater than 6 mm.

Thyroiditis (Overview)

• Inflammation or infection of the thyroid gland.
• Symptoms: Pain, fever, enlarged and edematous gland, feeling of fullness in the throat and tenderness.
• Various types: Acute suppurative, de Quervain's, Hashimoto's. Inflammatory patterns may include specific findings such as abscesses and/or inflammatory nodes.

Thyroiditis (Specific types)

• Acute Suppurative Thyroiditis: Rare bacterial infection, commonly in the pediatric population, with inflammation patterns of enlarged gland, decreased echogenicity, and increased vascularity (including possibly abscess formation).

• de Quervain's Thyroiditis: Viral infection, with ultrasound patterns similar to other thyroiditis findings.

• Hashimoto's Thyroiditis: Most common, often painless but characterized by diffuse gland enlargement, more common in females than males. Associated with hypothyroidism (↓T3 & T4). May be caused by autoimmune diseases, antibodies, and pregnancy. Ultrasound may show enlarged gland that progressively shrinks to a small, atrophic gland, decreased echogenicity, heterogeneity and micronodulation(multiple, tiny nodules <6 mm).

Grave's Disease

• Common cause of diffuse enlargement of the gland, associated with hyperthyroidism (↑T3 & T4), with various clinical and measurable indicators.
• Can be asymptomatic.
• Enlarged gland, heterogeneous echotexture, reduced echogenicity, with prominent intraparenchymal (internal to the gland) blood vessels, hypervascularity easily apparent on color doppler.

Diffuse Thyroid Hyperplasia (Multinodular Goiter)

• Diffuse overgrowth of the thyroid, most common in thyroid abnormalities, occurring after age 50 frequently in females.
• Could be inherited or related to iodine deficiency.
  • Enlarged thyroid, heterogeneous, composed of multiple indistinguishable nodules throughout the gland, which may extend into the mediastinum and have an uneven appearance (heterogeneous).

Parathyroid Gland Pathology

• Ectopic parathyroid glands.
• Parathyroid masses.
• Hyperparathyroidism.

Parathyroid Masses (characteristics)

• Parathyroid adenoma: Benign neoplasm, typically single.
• Parathyroid hyperplasia: Benign overgrowth, usually multiple. Commonly associated with MEN I syndrome, a hereditary disorder.
• Parathyroid carcinoma: Rare malignant neoplasm.
• Sonographic Appearance: Most are solid masses, posterior to thyroid, can be ectopic, size from 1.5cm to 5cm, homogeneous hypoechoic appearance, and hypervascular on Color Doppler (when present)

Other Neck Pathology

• Branchial cleft cyst: Remnants of embryonic branchial cleft, typically to the side of the thyroid, commonly found in young children, easily seen on ultrasound if present.
  • Sonographic Appearance: Can be cystic (with possible complexities such as septations and fluid levels) and can be infected (with debris).
• Thyroglossal duct cyst: Remnants of embryologic thyroglossal duct, midline, anterosuperior to thyroid and has variable appearance
  • Sonographic Appearance: Can be cystic (with possible complexities including septations & fluid-debris levels).
  • Symptoms may include pain and fever.
• Lymphadenopathy: Enlarged lymph nodes. Benign and malignant types differ in ultrasound appearance, with benign nodes typically being oval, 1-2 cm, hypoechoic with fatty, echogenic central hilum. Malignant nodes are smaller, round to oval, have a long/transverse ratio < 2, and more eccentricities in echogenicity, lacking central hilum, and no vascularity

Interventions

• Fine Needle Aspiration/Biopsy: Often used for indeterminate neck masses; particularly nodules >1.5 cm.
  • Results are classified as 4 categories (negative, positive for malignancy, suggestive of malignancy, and nondiagnostic/inadequate sampling.)
• Thyroidectomy: Surgical procedure for removal of all or part of the thyroid gland. Post-operative follow-up is a common protocol and may include ultrasound.