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

Benign thyroid lumps may include:

• Thyroid adenoma
• Thyroiditis
• Thyroid cysts
• Hyperplastic nodules

See also our separate articles on Thyroid Cancer and Neck Lumps and Bumps.

Epidemiology

• About 8% of women and 2% of men have thyroid lumps.
• 95% are benign.
• Thyroid nodules are found in approximately 1.5% of children and adolescents, being 6 times more common in girls than boys.

Risk factors

• Lumps are more common in areas of low iodine consumption and the incidence of malignancy rises from 5% to as high as 40%.
• Malignancy is more common where benign thyroid disease has existed.
• The risk of malignancy rises with age.
• Thyroid cancers are more common after exposure to radiation with a peak 5 to 30 years later.¹

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 2nd and 3rd fingers of both hands to examine the gland as she/he swallows again.
• Note lumps, asymmetry, size and tenderness.
• Check for regional lymphadenopathy.

Differential diagnosis

• Non toxic goitre - non-functioning nodules
• Toxic nodular goitre - functioning nodules
• Grave's disease - diffuse overactive thyroid gland
• Hashimoto's disease - autoimmune destruction of the gland
• Solitary thyroid nodule - 15 to 25% are cysts and can be aspirated
• Thyroid carcinoma
• Medullary cell carcinoma
• Thyroid lymphoma - usually non-Hodgkin's
• De Quervain 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

Investigations

• Perform thyroid function tests. (Most will be euthyroid - refer those which are abnormal for endocrine opinion.³)
• Ultrasound (US) is useful to detect and characterise most thyroid nodules. It can show cystic lesions 2 mm wide and solid lesions 3 mm wide. Ultrasound examination is far more sensitive than clinical examination and only 4-7% of nodules detected by US are clinically palpable.
• Fine needle aspiration (FNA) gives tissue for cytology. It is performed under US guidance (for maximum accuracy) but for palpable nodules it can be performed with palpation. It is safe, inexpensive and provides direct information.
  FNA is best for uninodular lesions.⁴ Sensitivity is near 80% with specificity approaching 100%. False-negative and false-positive results occur in less than 6%. FNA is the first, and in the vast majority of cases after US, the only test required for the evaluation of a solitary thyroid nodule.^5,6
• Radionuclide imaging looks at iodine uptake by the thyroid:
  • Normal is called "warm".
  • Lesions that take up excessive amounts of iodine are called "hot" - 4% of hot nodules contain tumour.
  • Lesions that do not take up iodine are called "cold" - 16% of cold nodules contain tumour.
  This makes radionuclide imaging unreliable to exclude or confirm cancer.
  
  Low ¹²³I uptake in a single palpable nodule gives a risk of malignancy of 10-25%, falling to 1-3% if multiple nodules are demonstrated on the scan.
• CT scans and MRI scans are valuable to detect local and mediastinal spread and regional lymph nodes.

Management

See Management section in articles Thyroid Carcinoma and Benign Thyroid Tumours.