About This Page
This is a clinician-written, evidence-based guide aligned to the MCC Examination Objectives. It is structured by clinical presentation — the way the MCCQE tests and the way patients actually present. Management reflects current Canadian guidelines (CMA, CFPC, CPS). Always cross-reference with institutional protocols and clinical judgment.
The Bottom Line
- A thyroid nodule is evaluated for three questions: malignant, functioning, or compressive
- First-line tests are TSH and thyroid/neck ultrasound for a palpable nodule or goitre
- Suppressed TSH changes the pathway: radionuclide scan identifies a hyperfunctioning nodule, which is rarely malignant
- FNA is guided by ultrasound risk pattern, size, suspicious lymph nodes, and clinical risk factors
- Red flags include hard fixed nodule, rapid growth, hoarseness, dysphagia, stridor, lymphadenopathy, radiation exposure, and family history
Approach to the Presentation
Thyroid enlargement may be patient-detected, examination-detected, or incidental on imaging. Begin with airway and compressive symptoms, malignancy risk, thyroid function, and whether the lesion is diffuse goitre, solitary nodule, multinodular thyroid disease, thyroiditis, or a non-thyroid neck mass. In Canadian practice, TSH plus high-resolution thyroid/neck ultrasound provides initial risk stratification. If TSH is low, radionuclide scanning determines whether the nodule is autonomous. If ultrasound shows suspicious features or lymph nodes, FNA and specialist referral are required.
Differential Diagnosis
| diagnosis | likelihood | key features | distinguishing test |
|---|---|---|---|
| Thyroid Cancer | must-not-miss | Hard fixed nodule, rapid growth, hoarseness, dysphagia, cervical lymphadenopathy, childhood radiation, family history of thyroid cancer or MEN2 | Neck ultrasound with suspicious features and ultrasound-guided FNA cytology |
| Airway-compressive Goitre | must-not-miss | Dyspnea, stridor, dysphagia, choking when supine, Pemberton sign, large retrosternal goitre | Urgent airway assessment; ultrasound and CT neck/chest if retrosternal or compressive features |
| Anaplastic Thyroid Cancer or Thyroid Lymphoma | must-not-miss | Older patient, rapidly enlarging firm neck mass, compressive symptoms, hoarseness; lymphoma may occur with Hashimoto thyroiditis | Urgent imaging and tissue diagnosis; core biopsy may be needed |
| Toxic Adenoma / Toxic Multinodular Goitre | must-not-miss | Nodule or multinodular goitre with weight loss, tremor, heat intolerance, AF, osteoporosis, suppressed TSH | Suppressed TSH plus radionuclide scan showing autonomous uptake |
| Benign Colloid Nodule | common | Soft mobile slow-growing euthyroid nodule without suspicious nodes or compression | Ultrasound low-risk pattern; FNA or surveillance according to risk/size |
| Multinodular Goitre | common | Irregular enlarged thyroid with multiple nodules; may be euthyroid, hyperthyroid, or compressive | Ultrasound of all nodules; sample highest-risk nodules rather than largest alone |
| Hashimoto Thyroiditis | common | Diffuse firm goitre, hypothyroid symptoms, family autoimmune disease, positive anti-TPO antibodies | High TSH, low/normal free T4, anti-TPO positive; ultrasound if true nodule suspected |
| Graves Disease with Goitre | common | Diffuse smooth goitre with bruit, ophthalmopathy, tremor, heat intolerance, weight loss | Suppressed TSH, elevated free T4/T3, TSH receptor antibodies |
| Subacute Thyroiditis | less common | Painful tender thyroid after viral illness, fever, transient thyrotoxicosis then hypothyroid phase | High ESR/CRP, suppressed TSH early, low radionuclide uptake |
| Non-thyroid Neck Mass | less common | Lymphadenopathy, branchial cleft cyst, salivary mass, thyroglossal duct cyst, metastatic head and neck cancer | Focused neck exam, ultrasound, ENT assessment and biopsy if persistent/suspicious |
Red Flags & Key History
Symptoms
Hoarseness, voice change, dysphagia, stridor, dyspnea, or choking when supine
Rapid enlargement over weeks to months
History of childhood head and neck radiation or total body irradiation
Family history of medullary thyroid cancer, MEN2, or thyroid cancer in a first-degree relative
Systemic B symptoms or rapidly enlarging mass in Hashimoto thyroiditis — consider lymphoma
Heat intolerance, tremor, weight loss, palpitations — functioning nodule or Graves disease
Cold intolerance, fatigue, constipation, weight gain — Hashimoto thyroiditis or hypothyroid goitre
Signs
Hard, fixed, irregular nodule
Cervical lymphadenopathy, especially firm lateral nodes
Stridor, Pemberton sign, or tracheal deviation
Vocal cord dysfunction or hoarse voice
Thyroid bruit and diffuse vascular goitre suggesting Graves disease
Tender thyroid suggesting subacute thyroiditis
Approach to Investigation
First-line
TSHInitial biochemical test for any thyroid nodule. If low, measure free T4/T3 and consider radionuclide scan before FNA decisions
Thyroid and neck ultrasoundCharacterises size, composition, echogenicity, margins, calcifications, taller-than-wide shape, extrathyroidal extension, and cervical nodes
Focused neck and cranial nerve examinationAssess mobility with swallowing, lymph nodes, voice, compressive features, and whether the mass is thyroidal
Free T4/T3 if TSH abnormalClassifies hyperthyroid or hypothyroid state
Second-line
Radionuclide thyroid uptake scanIndicated when TSH is suppressed. Hot nodules are usually not biopsied unless concerning features demand specialist assessment
Ultrasound-guided FNAFor nodules meeting ultrasound size/risk criteria or suspicious lymph nodes. Cytology is commonly reported using Bethesda system
Anti-TPO or TSH receptor antibodiesUseful when Hashimoto thyroiditis or Graves disease is suspected clinically and biochemically
Specialist
ENT/endocrinology referralSuspicious cytology, suspicious lymph nodes, compressive symptoms, retrosternal goitre, medullary cancer concern, indeterminate cytology, or hyperfunctioning nodules
CT neck/chestFor compressive or retrosternal goitre, invasive cancer concern, or surgical planning
Management Principles
Canadian thyroid nodule primary care pathways + Choosing Wisely Canada endocrine recommendations1
Initial triage
- Airway symptoms, stridor, rapidly enlarging mass, hoarseness, or suspicious lymph nodes require urgent referral
- Order TSH and thyroid/neck ultrasound for a palpable thyroid nodule or true goitre
- Do not order thyroid ultrasound solely for abnormal thyroid function tests unless the gland is enlarged or nodular on examination
2
Nodule pathway
- If TSH is normal or high: use ultrasound risk category and size to decide FNA versus surveillance
- If TSH is suppressed: assess free T4/T3 and radionuclide uptake; autonomous nodules are managed as hyperthyroidism
- If FNA is benign: arrange ultrasound surveillance only when indicated by risk pattern and size
3
Cancer or compressive concern
- Refer to endocrinology, ENT/head and neck surgery, or thyroid cancer pathway according to local practice
- Evaluate vocal cord function and nodal disease where surgery is planned or voice symptoms are present
- Medullary cancer concern or MEN2 family history requires specialist endocrine genetics assessment
Complications & Pitfalls
- Ultrasound overuse: Choosing Wisely Canada advises against routine thyroid ultrasound for abnormal thyroid function tests without palpable abnormality
- Biopsying before checking TSH: A suppressed TSH should prompt functional assessment because hot nodules are rarely malignant
- Sampling the largest nodule only: In multinodular goitre, the highest-risk ultrasound pattern should guide FNA selection
- Missing compressive symptoms: Stridor, dysphagia, hoarseness, and Pemberton sign change urgency
- Ignoring suspicious lymph nodes: Lymph node FNA may be more diagnostic than nodule FNA
MCCQE1 Exam Tips
- 1For a palpable thyroid nodule, first-line testing is TSH plus thyroid ultrasound
- 2If TSH is suppressed, order radionuclide scan before routine FNA
- 3Hard fixed nodule + hoarseness + lymphadenopathy = thyroid cancer until proven otherwise
- 4Do not investigate abnormal thyroid function tests with ultrasound unless there is palpable goitre or nodule
- 5FNA is based on ultrasound risk and size, not simply incidental discovery
- 6Medullary thyroid cancer clues: MEN2, pheochromocytoma features, or associated hyperparathyroidism
- 7Explain that most thyroid nodules are benign while safety-netting voice change, growth, and compressive symptoms
practicetest your knowledge on thyroid enlargement / thyroid noduleApply what you've learnt with MCCQE1-style questions from the iatroX Q-Bank — endocrine & metabolic and beyond.
open q-bank