Thyroid lumps

What are thyroid lumps?

Most thyroid lumps are benign but around 5% are malignant and it is important to distinguish this sinister minority.¹

The term goitre refers to enlargement of the thyroid gland. A thyroid nodule may be a lump in an otherwise normal thyroid gland. However, goitres may consist of many nodules (multinodular goitre) and solitary nodules may exist within a goitre. Nodules may be cystic, colloid, hyperplastic, adenomatous or cancerous.

Iodine deficiency is the most common cause of goitre worldwide, but not common in the UK.² In countries where iodine is added to salt, autoimmune conditions (Hashimoto's thyroiditis and Graves' disease) are more common causes. Medication (such as lithium and amiodarone) may cause thyroid enlargement. It may also occur in pregnancy and menopause.

See also the separate articles Thyroid cancer and Neck lumps and bumps.

How common are thyroid lumps? (Epidemiology)³

• Between 4-7% of adults have palpable thyroid lumps. Many more will be detectable on high-definition ultrasonography. Up to 40% of people having an ultrasound scan on their neck are found to have a thyroid nodule incidentally, and similar numbers are found incidentally at autopsy. 95% of these thyroid lumps in adults are benign.

• Thyroid cancer represents 1% of all malignancies.

• Thyroid nodules are uncommon in children and adolescents (1-1.5% are estimated to have palpable lumps). However, the risk of nodules being cancerous in this population is higher.⁴

Risk factors⁵⁶

• Goitres and thyroid lumps are more common in areas of low iodine consumption. This is less likely in countries where iodine is added to table salt.

• Conversely, excessive consumption of iodine (found in seaweed) can cause goitres.

• Malignancy is more common where benign thyroid disease has existed.

• The risk of malignancy in a thyroid nodule is higher under the age of 20 and over the age of 70.³

• Thyroid nodules and cancers are more common after exposure to radiation. This includes therapeutic radiotherapy, and exposure to radiation following events such as those in Hiroshima and Chernobyl.

• Smoking increases the risk of nodular goitre.

• Family history.

• Medication such as amiodarone and lithium.

There is some evidence that milk-alternative drinks pose a possible increased risk for iodine deficiency in the UK.⁷ This study examined the iodine content of 47 milk alternatives, including soya, almond, coconut, oat, rice, hazelnut, and hemp, and compared it with that of cows' milk. The majority of milk-alternative drinks did not have adequate levels of iodine, with concentrations found to be around 2% of that found in cows' milk. It is important that people who consume milk-alternative drinks realise that they will not be replacing the iodine from cows' milk which is the main UK source of iodine. This is particularly important for pregnant women and those planning a pregnancy.

Presentation

Symptoms

• Thyroid lumps are often asymptomatic and are noticed by family members or seen in the mirror.

• They may sometimes cause pain and rarely present with features of compression of the trachea.

• Ask about previous radiation.

Signs

• Ask the patient to drink some water and note the thyroid move as she/he swallows.

• Note enlargement or asymmetry.

• Stand behind a seated patient and use the second and third fingers of both hands to examine the gland as she/he swallows again.

• Note lumps, asymmetry, size and tenderness.

• Check for regional lymphadenopathy.

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Referral⁸

Emergency hospital admission

• If symptoms of upper airway obstruction, such as stridor.

Urgent referral

• An unexplained thyroid lump.

• A thyroid mass associated with unexplained hoarseness or voice change.

• A thyroid mass associated with cervical lymphadenopathy or supraclavicular lymphadenopathy.

• Sudden onset of a rapidly expanding painless thyroid mass, significantly increasing in size over days and weeks.

• A suspected thyroid nodule with associated compressive symptoms, such as breathlessness or dysphagia.

• Child with a thyroid nodule or goitre.

The National Institute for Health and Care Excellence (NICE) recommends: Consider a suspected cancer pathway referral for thyroid cancer in people with an unexplained thyroid lump. In a suspected cancer pathway referral, a person should receive a diagnosis or ruling out of cancer within 28 days of being referred urgently by their GP for suspected cancer.⁹

Non-urgent referral

• Thyroid nodules with abnormal TFTs. Refer to an endocrinologist.

• Sudden onset of pain within a thyroid lump. (Likely cause is a bleed into a thyroid cyst.)

• A thyroid nodule picked up incidentally on an ultrasound scan, CT, or MRI, which is more than 1 cm in diameter, if there are no suspicious features of malignancy.

Suspicion of malignancy includes a known diagnosis or symptoms suspicious of local malignancy (eg, upper airway or upper gastrointestinal tract), or haematological malignancy (eg, leukaemia or lymphoma). Have a higher index of suspicion for malignancy if the person is 40 years of age or older.

Do not routinely arrange further investigations such as a neck ultrasound scan in primary care, as this may cause diagnostic delay.

Consider monitoring in primary care if there is:

• An adult with a history of a longstanding unchanging thyroid nodule or mass over several years, with no palpable cervical lymphadenopathy and no other red flags or risk factors for malignancy.

• A non-palpable, asymptomatic thyroid nodule picked up incidentally on an ultrasound scan, CT, or MRI, which is less than 1 cm in diameter, with no associated lymphadenopathy and no other red flags or risk factors for malignancy.

Differential diagnosis

Thyroid lumps and swellings

• Non-toxic (simple) goitre - non-functioning nodules. TFTs are normal.

• Toxic multinodular goitre - functioning nodules. TFTs are abnormal.

• Retrosternal goitre (usually multinodular).

• Hyperplastic nodule (single nodule or part of multinodular goitre).

• Colloid nodule.

• Thyroid adenoma.

• Thyroid cyst.

• Thyroid carcinoma.

• Graves' disease - diffusely enlarged overactive thyroid gland.

• Hashimoto's thyroiditis - autoimmune destruction of the gland may cause diffuse enlargement.

• Other types of thyroiditis:

  • De Quervain's thyroiditis - neck pain, fever and lethargy soon after an upper respiratory infection or a viral illness.

  • Acute suppurative thyroiditis - results from bacterial or fungal infection causing abscess.

Non-thyroid lumps and swellings

• Congenital and developmental swellings:

  • Thyroglossal cyst

  • Branchial cyst

  • Pharyngeal pouch

  • Dermoid cyst

  • Laryngocele

• Lymph nodes - swelling due to inflammation, infection or malignancy.

• Salivary gland swellings - tumours, calculi, inflammation

• Non-thyroid benign and malignant tumours - lipomas, fibromas, vascular tumours, sarcomas.

Diagnosing thyroid lumps (Investigations)

Thyroid function tests

GPs are recommended to perform TFTs to determine the need for referral, and if so to whom.

• Those with abnormal TFTs and no suspicious features should be referred to an endocrinologist.

• Those with thyroid swelling and normal TFT should be referred under the timeline in the 'Red flag features' section above.

Those patients with a new thyroid swelling where cancer is suspected, GPs should refer under two-week wait rule.¹⁰ Referral should be to a surgeon, endocrinologist or other member of a specialist multidisciplinary team.

Ultrasound

This is highly sensitive for detection and characterisation of thyroid nodules¹¹. It is far more sensitive than clinical examination and only a small percentage of nodules detected by ultrasound are clinically palpable. Ultrasound helps to inform which nodules need aspiration for cytology.

Fine-needle aspiration (FNA)

This provides tissue for cytology. It is performed under ultrasound guidance for maximum accuracy¹¹. It is safe, inexpensive and provides direct information.

Basal plasma calcitonin and carcinoembryonic antigen (CEA)

These are not used routinely but are measured if medullary thyroid cancer is suspected.

CT scans and MRI scans

These may be needed to detect local and mediastinal spread and regional lymph nodes if a neoplastic cause is identified.

Management of thyroid lumps