PassFinals
ENT

Thyroid Nodules and Cancer

Thyroid nodules are common and usually benign; assess a clinically concerning lump with thyroid function tests, greyscale ultrasound and ultrasound-guided FNAC when the established ultrasound threshold is met, then manage cytology and cancer by risk and subtype.

In a nutshell

Thyroid nodules are common and mostly benign. Assess a concerning lump with thyroid function tests, greyscale ultrasound and ultrasound-guided FNAC when the established ultrasound threshold is met. Use the Thy cytology result to choose surveillance, repeat sampling, diagnostic hemithyroidectomy or therapeutic surgery; differentiated cancer treatment then depends on stage, nodes, histology and response.

Classic presentation

A euthyroid adult with a painless thyroid lump that moves on swallowing; rapid growth, fixation, cervical nodes, hoarseness, dysphagia, stridor, childhood irradiation or relevant family history increases concern.

Key points

  • TSH is the first thyroid-function test in adults when secondary dysfunction is not suspected; low TSH prompts FT4/FT3 testing and a thyrotoxicosis pathway, not automatic cancer exclusion.
  • NICE recommends greyscale ultrasound with an established grading system, followed by ultrasound-guided FNAC when the threshold is met.
  • Thy1/Thy1c are inadequate or cystic, Thy2 is benign, Thy3a is indeterminate, Thy3f suggests follicular neoplasm, Thy4 is suspicious and Thy5 is malignant.
  • Follicular carcinoma requires histological evidence of capsular or vascular invasion; FNAC cannot establish it alone.
  • For differentiated cancer, solitary node-negative T1a disease may be observed or treated with hemithyroidectomy; higher-risk disease may need total thyroidectomy, RAI and risk-adapted TSH suppression.
  • Medullary, anaplastic and thyroid lymphoma need subtype-specific specialist pathways; do not apply RAI and thyroglobulin rules automatically.

First-line investigation

TSH, with FT4/FT3 added according to the result, then greyscale neck ultrasound using an established grading system; perform ultrasound-guided FNAC when indicated.

Management

Protect the airway and escalate red flags

  • Stridor, respiratory distress or a rapidly enlarging obstructive neck mass requires immediate senior ENT/head-and-neck and anaesthetic assessment.3,1

Refer and investigate systematically

  • Use the current suspected-cancer pathway, check TSH with reflex FT4/FT3 as indicated, and arrange greyscale ultrasound with an established grading system.3,2,1

Let ultrasound and Thy cytology determine the next step

  • Use ultrasound-guided FNAC when the threshold is met and follow the Thy1–Thy5 pathway; remember that follicular carcinoma needs histology.1

Treat differentiated cancer by risk

  • Consider active surveillance or hemithyroidectomy for solitary node-negative T1a disease; use hemithyroidectomy/total thyroidectomy, nodal surgery and completion surgery according to stage, histology and structural disease.1,5

Explain the consequences of surgery and treatment

  • Discuss hypothyroidism and replacement, hypoparathyroidism/hypocalcaemia, voice change, swallowing problems and the need for ongoing thyroid-function monitoring; use the current BNF and specialist plan for prescribing.1,7

Use risk-stratified surveillance

  • Use ultrasound and clinical follow-up after surgery without RAI, and use thyroglobulin with anti-thyroglobulin antibodies and risk-stratified follow-up after total/completion thyroidectomy and RAI.1

Keep non-differentiated cancers on specialist pathways

  • Medullary, anaplastic and primary thyroid lymphoma require subtype-specific MDT diagnosis and treatment; do not assume RAI or thyroglobulin monitoring applies.1,4

Exam traps

  • A low TSH changes the thyroid-function work-up but does not replace ultrasound or automatically rule out malignancy.
  • NICE does not recommend routine radioisotope scanning as the initial test for thyroid cancer.
  • Thy3a and Thy3f are not interchangeable: persistent Thy3a may be surveilled or sampled again, whereas Thy3f commonly leads to diagnostic hemithyroidectomy.
  • Thyroglobulin is not a useful routine tumour marker when thyroid tissue remains after hemithyroidectomy.
  • Do not routinely perform prophylactic central or lateral neck dissection; structural nodal disease is managed with compartment-oriented surgery.
  • Do not call thyroid cancer a ‘good cancer’; explain prognosis without minimising the diagnosis.

Illustrations

Hypoechoic thyroid nodule on ultrasound with caliper measurementsA thyroid ultrasound showing a hypoechoic nodule that is taller than wide with microcalcification and an irregular margin; use as a visual prompt for suspicious features, while the current local ultrasound grading system and clinical context determine whether FNAC is indicated.Nevit Dilmen (talk), Wikimedia Commons · CC-BY-SA-3.0
Papillary thyroid carcinoma metastatic to a lymph nodeA low-power histology section showing metastatic papillary thyroid carcinoma replacing part of a lymph node, illustrating differentiated thyroid cancer and structural nodal disease.Nephron, Wikimedia Commons · CC-BY-SA-3.0

Key sources

  1. NICE NG230, Thyroid cancer: assessment and management (NG230)Updated 4 Mar 2026
  2. NICE NG145, Thyroid disease: assessment and management (NG145)
  3. NICE NG12, Suspected cancer: recognition and referral (NG12)Updated 15 Apr 2026
  4. Cambridge University Hospitals, Thyroid cancer (CUH thyroid cancer service)Updated 26 Jul 2026
  5. NHS, Treatment for thyroid cancer (NHS thyroid cancer treatment)Updated 18 May 2023
  6. NHS, Tests and next steps for thyroid cancer (NHS thyroid cancer tests and next steps)Updated 18 May 2023
  7. British National Formulary, online prescribing information (BNF)

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.