Thyroid Disorders and RLN Injury Quiz

Injury of the Recurrent Laryngeal Nerve (RLN)

• Dyspnea, stridor, hoarseness of voice and aphonia are all symptoms of RLN injury.
• Unilateral injury leads to hoarseness.
• Bilateral injury results in aphonia.

Imaging

• Plain X-ray of the neck and upper chest can reveal a soft tissue shadow indicating a retrosternal goiter.
• Ultrasound: is used to differentiate cystic from solid nodules and detect clinically impalpable nodules.
• CT scan of the neck can show retrosternal goiter and cervical lymph nodes.
• Biopsy is used for suspected malignancy.
• Indirect laryngoscopy is used to assess the vocal cords.

Common Investigations

• TSH, FT3, and FT4 are routinely conducted.
• Thyroid auto-antibodies are tested to exclude Hashimoto’s thyroiditis.
• Ultrasound and FNAC are considered essential.
• Thyroid tumor markers like calcitonin are used to detect medullary cancer.

Definition of Goiter

• Goiter is an enlarged thyroid gland regardless of the cause or function.

Clinical Features of a Thyroid Swelling

• Goiters are typically located in the lower anterior part of the neck, deep to the sternomastoid muscle.
• The shape is usually butterfly-like, but enlargement can be unilateral or asymmetrical.
• A goiter moves up and down with deglutition.
• A Thyroglossal cyst moves upwards with protrusion of the tongue.

Clinical Types of Goiter

• Simple Goiter:
  • Diffuse:
    • Physiological
    • Colloidal
  • Multinodular
  • Solitary Nodule
  • Recurrent Nodular
• Toxic Goiter:
  • Diffuse:
    • Grave's Disease
  • Multinodular:
    • Marine Lenhart Syndrome
  • Solitary Nodule:
    • Plummer's Disease
  • Recurrent Nodular
• Special Goiter:
  • Thyroiditis
  • Neoplastic:
    • Benign: Adenoma
    • Malignant: 1 or 2
  • Autoimmune
  • Congenital (dyshormogenesis)

Personal History in Goiter

• Young patients between 25-40 years old are more likely to have physiological goiter, papillary carcinoma, and SNG (single nodular goiter).
• Patients between 30-45 years old are more susceptible to thyrotoxicosis.
• Elderly patients are at risk for cancer of the thyroid.
• Women are more prone to goiter than men.
• Males are more likely to develop retrosternal goiter and malignant solitary thyroid nodules.

Symptoms of Goiter

• Sudden appearance or rapid increase in size of the goiter can be due to Graves' disease.
• Eye signs include exophthalmos, lid lag, and stare.
• Other symptoms include tremors, chemosis, ophthalmoplegia, dilated congested conjunctival blood vessels, and tremors of the eyelids.
• Dullness over the manubrium on percussion suggests retrosternal goiter.

Signs of Retrosternal Extension

• History: Postural dyspnea, stridor, cough, wheezing, choking, dysphagia.
• Physical examination:
  • Dilated veins in front of the neck and sternum.
  • Enlarged thyroid with non-visible lower border on swallowing.
  • Impalpable lower border on palpation.
  • Dullness on percussion over the manubrium sterni.
  • Flushing of the skin and dilatation of the EJV during raising the arms or hyperextension of the neck (Positive Pemberton's Sign).

Primary vs. Secondary Thyrotoxicosis

• Age:
  • Primary thyrotoxicosis is common in young adults.
  • Secondary thyrotoxicosis is more prevalent in older age groups.
• Onset of toxic symptoms:
  • Primary thyrotoxicosis: Symptoms appear simultaneously with the swelling.
  • Secondary thyrotoxicosis: Symptoms appear after the swelling.
• Eye signs:
  • Primary thyrotoxicosis: Marked eye signs.
  • Secondary thyrotoxicosis: Mild eye signs.
• Nervous manifestations:
  • Primary = +++
  • Secondary = +
• Cardiovascular symptoms:
  • Primary = +++
  • Secondary = +
• Gastrointestinal manifestations:
  • Primary = +++
  • Secondary = +
• Increased BMR:
  • Primary= +++
  • Secondary = +
• The Gland:
  • Primary: Diffuse, smooth, symmetrical, bilateral, and fleshy.
  • Secondary: Nodular, asymmetrical, and may be unilateral.

Toxic (Grave's) vs. Colloid Goiter vs. Thyroiditis

• Size:
  • Toxic (Grave's): Slight to moderate
  • Colloid Goiter: Moderate to gross
  • Thyroiditis: Small or moderate
• Surface:
  • Toxic (Grave's): Smooth
  • Colloid Goiter: Bosselated
  • Thyroiditis: Smooth
• Consistency:
  • Toxic (Grave's): Soft-Fleshy
  • Colloid Goiter: Fleshy
  • Thyroiditis: Hard
• Tenderness:
  • Toxic (Grave's): -
  • Colloid Goiter: -
  • Thyroiditis: -
• Bruit:
  • Toxic (Grave's): +
  • Colloid Goiter: -
  • Thyroiditis: -

Complications of Multinodular Goiter

• Toxicity
• Malignancy
• Retrosternal extension
• Pressure
• Cyst formation
• Calcification
• Hemorrhage
• Infection (rare due to extensive vascularity)

Criteria of Malignant Transformation

• Glandular criteria:
  • Rapid growth
  • Fixation
  • Hard consistency
  • Ill-defined edge
  • Onset of pain
• Extraglandular criteria:
  • Pressure
  • Vocal cord paralysis
  • Horner syndrome
  • Cervical lymph nodes
  • Unequal carotid pulsations
  • Distant metastases

Benign Tumors of the Thyroid

• Epithelial Tumors:
  • Papillary adenoma (fetal or microfollicular adenoma)
  • Follicular adenoma (cystadenoma or colloid adenoma)
• Mesenchymal Tumors:
  • Lipoma
  • Leiomyoma
  • Hemangioma
• Other Tumors:
  • Teratoma (mainly in children)

Malignant Tumors of the Thyroid

• A painless enlarging lesion with one or more of the following should raise suspicion of malignancy:
  • Radiation exposure
  • Male gender
  • Older age
  • Younger age
  • Rapid increase in size
  • Previous thyroid cancer
  • Lymphadenopathy
  • Evidence of local invasion (vocal cord paralysis, dysphagia or firm, fixed nodules)

Familial Syndromes Associated with Thyroid Cancer

• Familial non-medullary thyroid cancer:
  • Gardner Syndrome: PTC (intestinal polyps, osteomas, fibromas, lipomas)
  • Cowden Syndrome: PTC - FTC (breast cancer, hamartomas, pigmented adrenal nodules, Schwannoma)
  • Carney Syndrome: PTC (myoma, pituitary adenomas, testicular tumors)

Thyroid Cancer Incidence

• Papillary: 80%
• Follicular: 15%
• Medullary: 2-10%
• Anaplastic: 5-15%
• Lymphoma: Rare
• Metastatic: Rare

Thyroid Cancer Classification

• Differentiated tumors of follicular origin (90-95%):
  • Papillary carcinoma
  • Follicular carcinoma
  • Hürthle cell carcinoma
• From parafollicular cells (2-10%):
  • Medullary thyroid carcinoma (MTC)
• Poorly differentiated (5-15%):
  • Anaplastic thyroid carcinoma (ATC)

Oncogenes Associated with Thyroid Carcinoma

• RET oncogene: Papillary (PTC) & MTC
• Mutated RAS oncogene: Follicular thyroid carcinoma (FTC)
• Mutated p53 gene: Anaplastic thyroid carcinoma (ATC)

Papillary Thyroid Carcinoma (PTC)

• Most common type of thyroid malignancy (80%)
• Predominant thyroid cancer in children
• May be due to radiation exposure of the neck
• Age: Peak incidence is in the third decade of life
• Gender (Female: male = 3:1)

Pathology of PTC

• Complex papillary projections with a fibrovascular core.
• Hallmarks of PTC:
  • Psammoma bodies (laminated calcified spheres)
  • Orphan Annie eye Nuclei or ground glass nuclei (nuclei with finely dispersed chromatin, optically clear or empty appearance)
• Incidence of multi-focality is 80%
• Spread to lymph nodes occurs in 30-50% of patients (no effect on survival).
• Hematogenous spread is rare, occurs late to lung and bones.

Investigations of PTC

• Ultrasonography (US)
  • Calcifications (thyroid microcalcifications, = Psammoma bodies)
  • Local invasion + LN metastases (irregular margins + heterogeneous echo-texture)
  • Shape: Taller than it is wide
  • Vascularity (color or power Doppler US): marked intrinsic hyper-vascularity
  • Hypoechoic solid nodule
• FNAC (specific and sensitive for PTC, MTC and ATC)
• CT / MRI for extensive local or sub-sternal extension

Surgery of PTC

• Hemithyroidectomy (lobectomy with isthmectomy) for minimal PTC
• Total thyroidectomy:
  • Size >4cm
  • Age (male >40 y, female >50y)
  • Angio-invasion
• Total thyroidectomy + Neck dissection: Metastatic cervical LNs.

Follicular Thyroid Carcinoma (FTC)

• It is the 2nd most common thyroid cancer (10%).
• More frequent in iodine deficiency areas (nodular goiter →neoplasm).
• Age: Mean age is 50 y.
• Gender: (Female: male = 3:1).

Features of FTC

• Occasional tumors are dominated by cells with abundant granular, eosinophilic cytoplasm (Hürthle cells).
• Requires extensive sampling of the tumor-thyroid capsule → capsular or vascular invasion.
• Hematogenous spread is more common (bone, lung and liver).

Diagnosis and Treatment of FTC

• FNAC is not helpful: Requires lobectomy and isthmectomy.

Follicular Thyroid Cancer Subgroups

• Low-risk group:
  • Younger patients
  • Without distant metastasis
  • Intra-thyroid follicular / papillary tumors
  • Tumors < 4cm in diameter
• High-risk group:
  • Older patients
  • Distant metastasis
  • Extrathyroid papillary/follicular tumors
  • Tumors >4 cm

Hürthle Cell Thyroid Tumor

• More common in males.
• Derived from oxyphilic cells of the thyroid gland.
• Spreads by lymphatics.
• Diagnosis: FNAC (20% malignant) - Often multifocal and bilateral.
• Treatment: Total thyroidectomy + Modified radical neck dissection (if with palpable cervical LNs).

Medullary Thyroid Carcinoma (MTC)

• Age: The peak incidence is at 50-60 years.
• Origin: parafollicular or C cells of the thyroid (neuroectodermal).
• Secrets calcitonin (95%); 85% secrets carcinoembryonic antigen (CEA).
• Sporadic 90%: Uni-focal, usually at 45y, worse prognosis.
• Familial 10%: Multifocal, usually 35 y, better prognosis, associated with:
  • MEN IIA or Sipples' syndrome (MTC, hyperplastic parathyroid and pheochromocytoma)
  • MEN IIB (MTC, pheochromocytoma, ganglioneuromatosis and Marfan's syndrome)
• Can secrete: Calcitonin (95%), СЕА (85%).
• Spread:
  • Lymphatics (neck and superior mediastinum)
  • Blood → liver, bone (osteoplastic) and lung
  • Local invasion
• Diagnosis: Serum calcitonin, CEA
• Treatment:
  • FNAC: characteristic amyloid stroma
  • Total thyroidectomy
  • MRND (Palpable cervical LN, tumor >2cm →chance of 60% nodal metastasis)
  • Screen for pheochromocytoma (MEN II) which should be resected first.
• Follow Up: Serum Calcitonin / CEA level
• Prognosis:
  • Best → worst prognosis: Familial non-MEN MTC → ΜΕΝ ΙΙΑ → sporadic cases → MEN IIB

Anaplastic Thyroid Carcinoma (ATC)

• Incidence: Uncommon, affecting older patients
• Origin: May arise in a well differentiated thyroid carcinoma
• 80% a history of a long-standing goiter with sudden and rapid growth
• Treatment:
  • Tracheostomy and total thyroidectomy (difficult due to injury risk)
  • External radiation (temporarily controls local effects)
  • Chemotherapy (limited effect)
• Prognosis is extremely poor + mean life expectancy of 6-9 months.
• Death occurs from local invasion of vital cervical structures + airway compression

Thyroid Lymphoma

• Non-Hodgkin B-cell lymphoma
• Hashimoto's thyroiditis is a risk factor
• Treatment: Chemotherapy / Radiotherapy

Test your knowledge on recurrent laryngeal nerve injuries, imaging techniques, and common investigations related to thyroid disorders. This quiz also covers the definition of goiter and pertinent symptoms associated with thyroid issues. Enhance your understanding of how these conditions are diagnosed and managed.