Special Surgery 2. Benign Diseases of the Thyroid Gland, and Treatment

I. Goiter: Definition, Etiology, Classification

Definition

• Goiter: Enlargement of the thyroid gland
• Can be diffuse or nodular
• Can be euthyroid, toxic/hyperthyroid, or hypothyroid
• Benign thyroid disease can still need surgery because of compression, hyperfunction, cosmesis, or malignancy suspicion

Etiology

• Iodine deficiency → Diffuse/simple goiter
• Autoimmune → Hashimoto thyroiditis, Graves-Basedow disease
• Thyroiditis → De Quervain, silent/postpartum, Hashimoto
• Idiopathic follicular hyperplasia
• Benign nodule, cyst, follicular adenoma
• Drug/iodine-related dysfunction → Amiodarone, lithium, excess iodine
• Radiation exposure → Nodule and cancer risk
• Thyroid malignancy must be excluded in suspicious nodular disease

Classification

1. Morphology

• Diffuse: Graves-Basedow disease, Hashimoto thyroiditis, iodine deficiency, thyroiditis
• Nodular: Cyst, adenoma, multinodular goiter, cancer

• Solitary nodule
• Multinodular goiter
• Retrosternal/substernal extension possible in large goiter

2. Function

• Non-toxic / euthyroid: Normal TSH and FT4/T3
• Toxic / hyperthyroid: Low TSH + high FT4/T3
• Hypothyroid: High TSH + low FT4 in primary hypothyroidism

II. Clinical Features and Diagnosis

Clinical Features

1. Local / Compressive Symptoms

• Visible neck swelling, cosmetic complaint
• Dyspnea, stridor, orthopnea → Tracheal compression/deviation
• Dysphagia → Esophageal compression
• Voice change/hoarseness → Recurrent laryngeal nerve irritation; malignancy must be considered
• Retrosternal goiter → Thoracic inlet compression, difficult airway

2. Hyperthyroidism

• Tachycardia, palpitations, systolic hypertension, atrial fibrillation/arrhythmia
• Heat intolerance, sweating, tremor, anxiety, insomnia
• Weight loss despite appetite, diarrhea, proximal muscle weakness
• Exophthalmos/orbitopathy → Graves-Basedow disease

3. Hypothyroidism

• Bradycardia, diastolic hypertension, fatigue
• Cold intolerance, dry skin, constipation
• Weight gain, muscle cramps/stiffness, cognitive slowing/depression

Physical Examination

• Inspection and palpation from behind the patient
• Ask patient to swallow → Thyroid mass moves with swallowing
• Assess nodule/goiter characteristics

• Size, side, diffuse vs nodular
• Consistency: soft, firm, hard
• Tenderness → Thyroiditis or hemorrhage
• Mobility/fixation
• Cervical lymph nodes
• Tracheal deviation and voice quality

Laboratory Diagnosis

• TSH: First screening test in goiter/nodule evaluation
• FT4/T3 if TSH abnormal or thyrotoxicosis suspected
• Hyperthyroidism → Low TSH + high FT4/T3
• Primary hypothyroidism → High TSH + low FT4
• Autoantibodies

• Graves-Basedow disease → TSH receptor Ab / TRAb / TSI / TSAb
• Hashimoto thyroiditis → Anti-TPO, anti-thyroglobulin Ab

Imaging and Cytology

• Ultrasound: First-line morphology test

• Size, number, solid/cystic nature, cervical lymph nodes
• Suspicious signs: hypoechoic solid nodule, irregular margin, microcalcification, taller-than-wide shape, suspicious lymph node
• Suspicious or size-threshold nodule → US-guided FNAB/FNA

• Scintigraphy: Mainly if TSH is low / autonomous function suspected

• Diffuse homogeneous uptake → Graves-Basedow disease / diffuse hyperactivity
• Hot nodule → Toxic adenoma; malignancy risk low
• Cold nodule → Non-secreting tissue, cyst or tumor → US risk assessment ± FNAB

• CT/MRI: Retrosternal goiter, airway/esophageal compression, mediastinal extension, difficult reoperation, invasive suspicion

III. Main Benign Thyroid Diseases

Diffuse Nontoxic / Simple Goiter

• Cause → Iodine deficiency, genetic factors, goitrogens
• Usually euthyroid; visible neck mass ± pressure symptoms if large
• Medical treatment → Observation if small/asymptomatic; iodine if deficient
• Levothyroxine suppression is less used today because of iatrogenic hyperthyroidism, AF and osteoporosis risk

Multinodular Goiter

• Multiple nodules, often asymmetric
• Function → Euthyroid, hypothyroid or toxic
• Risks → Retrosternal extension, airway compression, occult suspicious nodule
• Medical/non-surgical treatment → Observation if small/asymptomatic and benign; radioiodine in selected toxic cases

Thyroid Nodule and Follicular Adenoma

• Most thyroid nodules are benign, but malignancy must be excluded
• Benign cytology → US follow-up depending on size/risk/growth
• Follicular adenoma: Benign encapsulated follicular tumor
• Can be non-functional or hot/toxic
• Hot/toxic adenoma → Radioiodine is an option if suitable

Graves-Basedow Disease

• Autoimmune diffuse toxic goiter
• Mechanism → TSH receptor stimulating antibodies → Excess hormone production
• Typical triad → Hyperthyroidism + diffuse goiter + exophthalmos/orbitopathy
• Specific marker → Positive TRAb/TSI
• Treatment options:

1. Antithyroid drugs: Methimazole/carbimazole; PTU mainly first trimester pregnancy or thyroid storm context
2. Radioiodine I-131: Contraindicated in pregnancy/breastfeeding
3. Total thyroidectomy: Large goiter/compression, suspicious nodule, severe active orbitopathy where radioiodine unsuitable, relapse/intolerance of drugs, patient preference, selected pregnancy cases

• Before surgery → Make patient euthyroid with antithyroid drugs ± beta-blocker

Toxic Multinodular Goiter / Toxic Adenoma

• Autonomously functioning nodule(s) → Hyperthyroidism
• No Graves orbitopathy
• Antithyroid drugs → Temporary control, usually not definitive cure
• Radioiodine → Common definitive non-surgical option if suitable

Thyroiditis

1. Hashimoto Thyroiditis

• Chronic lymphocytic autoimmune thyroiditis
• Common cause of hypothyroidism in iodine-sufficient areas
• Anti-TPO ± anti-thyroglobulin Ab positive
• Firm painless goiter, hypothyroid symptoms; sometimes transient hyperthyroid phase
• Treatment → Levothyroxine if hypothyroid

2. Subacute / De Quervain Thyroiditis

• Post-viral, painful tender thyroid enlargement
• Elevated ESR/CRP, transient hyperthyroid phase → Possible hypothyroid phase → Usually recovery
• Treatment → NSAIDs; corticosteroids if severe
• Beta-blocker for symptoms; antithyroid drugs do not help because hormone release is inflammatory

3. Postpartum / Silent / Painless Thyroiditis

• Autoimmune-related, usually transient
• Painless goiter or mild enlargement possible
• Hyperthyroid phase → Hypothyroid phase → Recovery in many patients
• Treatment → Monitor; beta-blocker for symptoms; levothyroxine if significant/prolonged hypothyroidism

IV. Treatment and Surgical Consequences

Surgical Indications in Benign Thyroid Disease

• Large goiter with compression → Dyspnea, dysphagia, stridor, tracheal deviation/compression
• Large nodule >3-4 cm, growing nodule or symptomatic nodule
• Retrosternal/substernal goiter or difficult airway/compression risk
• Suspicious/indeterminate nodule on FNAB or malignancy concern
• Toxic adenoma / toxic multinodular goiter if large, compressive, suspicious, rapid control needed, or radioiodine unsuitable
• Failure, contraindication or intolerance of medical/radioiodine therapy
• Cosmetic reason or patient preference after counseling

Operations

• Lobectomy / hemithyroidectomy: Solitary benign nodule, toxic adenoma, unilateral indeterminate nodule
• Near-total / total thyroidectomy: Graves disease, bilateral multinodular goiter, large compressive goiter, recurrent goiter, malignancy suspicion depending on case
• Subtotal thyroidectomy: Older operation; less common now because recurrence and difficult reoperation
• Incision: Kocher collar incision: transverse lower cervical incision above suprasternal notch

Contraindications

• Severe uncontrolled comorbidities or high anesthesia risk → Relative/absolute depending on urgency
• Uncontrolled thyrotoxicosis → Risk of thyroid storm; make euthyroid before elective surgery
• Pregnancy → Elective surgery avoided; second trimester preferred if operation is unavoidable

Preoperative Preparation

• Preoperative laryngoscopy if voice change, previous neck surgery or cancer suspicion
• Large/retrosternal goiter → Airway plan

Complications of Thyroidectomy

• Bleeding / neck hematoma: Airway compression → Emergency wound opening may be lifesaving
• Recurrent laryngeal nerve palsy: Hoarseness, weak voice, choking/aspiration; bilateral palsy → airway obstruction
• External branch of superior laryngeal nerve injury: Voice fatigue, loss of high pitch
• Hypoparathyroidism: Hypocalcemia, paresthesia, tetany; mainly after total thyroidectomy
• Thyroid storm if hyperthyroid patient inadequately prepared
• Hypothyroidism → Lifelong levothyroxine after total thyroidectomy
• Wound infection, seroma, hypertrophic scar/keloid

Medical / Non-Surgical Treatment

• Observation + US follow-up → Small benign asymptomatic nodule/goiter
• Iodine supplementation → Iodine deficiency goiter
• Levothyroxine → Hypothyroidism/Hashimoto; suppression therapy for euthyroid goiter only selected cases
• Antithyroid drugs → Graves disease; temporary control of toxic nodular disease; PTU mainly first trimester pregnancy or thyroid storm context
• Beta-blocker → Symptomatic hyperthyroidism or thyroiditis thyrotoxic phase
• Radioactive iodine I-131 → Graves, toxic multinodular goiter, toxic adenoma

• Contraindicated: Pregnancy, breastfeeding
• Usually unsuitable: Suspicious nodule, severe compression, severe active orbitopathy unless protected/selected