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
- Thyroid cysts
- Hyperplastic nodules
- Most thyroid nodules are adenomatous. Most are multiple and that is usually shown on ultrasound, scintigraphy and at surgery. The nodules are usually non-functioning (cold at scintigraphy), although a few may be hyper-functioning toxic adenomas (hot on scintigrams). They may also be a hyper-functioning adenoma in a multinodular goitre.
- When solid, the nodules are poorly encapsulated and not well-defined, and they merge into the surrounding tissue. Cystic adenomatous nodules are haemorrhagic, with irregular internal walls and particulate fluid content. Intratumoral calcification is occasionally seen.
- Follicular adenomas are the most common and arise from follicular epithelium. They are usually single, well-encapsulated lesions. On ultrasound, adenomas may be hyperechoic or hypoechoic solid nodules with a regular hypoechoic area surrounding ring called the halo sign. Rarely, a parathyroid adenoma has an ectopic intrathyroid location.
- Whether solitary adenomas transform into follicular carcinoma is uncertain. In particular, whether aneuploid cells, which are present in approximately 25% of follicular adenomas, represent carcinoma in situ is unclear.
- Follicular adenomas are further classified according to their cellular architecture and relative amounts of cellularity and colloid into fetal (microfollicular), colloid (macrofollicular), embryonal (atypical), and Hürthle (oxyphil) cell types.
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About 40% of the general adult population has a single nodule or multiple ones. They are more common in women. Most nodules are benign.
In most series, 8-65% of patients with clinically normal thyroid glands had one or more grossly visible nodules, whereas the incidence of malignancy was 2-4%.
- Most patients with thyroid nodules are asymptomatic, and most nodules are found on clinical examination or self-palpation.
- A single dominant or solitary nodule is more likely to represent carcinoma (malignancy incidence 2.7-30%), than a single nodule within a multinodular gland (malignancy incidence 1.4 to 10%).
- 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.
- Ask the patient to drink some water and note the thyroid move as they swallow.
- Note enlargement or asymmetry.
- Stand behind a seated patient and use the 2nd and 3rd fingers of both hands to examine the gland as they swallow again.
- Note lumps, asymmetry, size and tenderness.
- Check for regional lymphadenopathy.
- Nodules larger than 4 cm in size.
- Firmness to palpation.
- Fixation of the nodule to adjacent tissues.
- Cervical lymphadenopathy.
- Vocal fold immobility.
- Non-toxic goitre - non-functioning nodules.
- Toxic nodular goitre - functioning nodules.
- Graves' disease - diffuse overactive thyroid gland.
- Hashimoto's disease - autoimmune destruction of the gland.
- Solitary thyroid nodule - 15-25% are cysts and can be aspirated.
- Thyroid carcinoma.
- Medullary cell carcinoma.
- Thyroid lymphoma - usually non-Hodgkin's.
- 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.
- TFTs will show most patients to be euthyroid - refer those which are abnormal for endocrine opinion.
- Ultrasound 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 ultrasound are clinically palpable.
- Fine-needle aspiration (FNA) gives tissue for cytology. It is performed under ultrasound guidance (for maximum accuracy). It is safe, inexpensive and provides direct information. The false-negative rate varies with the experience of the person performing the procedure. However, the false-negative rate for cancer can vary from 1% to 6% (owing to wrong diagnosis or sampling errors) even when the operator is experienced and the sample is sufficient for diagnosis. These errors occur more commonly in nodules smaller than 1 cm or larger than 4 cm.
- Radionuclide isotope scanning looks at iodine uptake by the thyroid and has a limited role in the diagnosis of thyroid cancer. The British Thyroid Association (BTA) does not support its routine use - it is "usually non-diagnostic of cancer". The American Thyroid Association recommends its use only in specific situations.
- CT scans and MRI scans are valuable to detect local and mediastinal spread and regional lymph nodes.
- The BTA recommends that patients with non-palpable nodules smaller than 1 cm that are discovered incidentally on imaging of the neck and with no worrying features, can be managed in primary care. The American Thyroid Association's guidelines state that usually no further investigations are required.
- New thyroid lumps that have been growing over a period of months, or patients with a sudden onset of pain in a nodule (which is usually due to a bleed into a cyst), should be referred to a specialist thyroid clinic with provisions for ultrasound and fine-needle aspiration (FNA) assessment, where they should be seen within four weeks of referral.
- Urgent referral to secondary care is necessary when:
- There is a solitary nodule increasing in size.
- There is history of neck irradiation.
- There is a thyroid nodule or goitre in a child or teenager.
- A family history of an endocrine tumour exists.
- Unexplained hoarseness or voice changes are noted.
- There is cervical lymphadenopathy (usually deep cervical or supraclavicular).
- The patient is aged 65 years or older.
- There has been enlargement of a painless thyroid mass over a period of weeks (may be indicative of thyroid cancer).
- Biochemical abnormalities of TFTs need to be treated in the usual way. Beta-blockers may be needed to control symptoms in some severely toxic patients.
- Patients with benign solitary thyroid nodules may have suppression therapy with thyroxine, although there is currently little evidence to support the practice.
Solitary thyroid nodules that are malignant, suspicious, or indeterminate on FNA require removal. There is controversy about which operation, with advocates for thyroid lobectomy, total or subtotal thyroidectomy.
Both surgery and alcohol injection can cause recurrent laryngeal nerve palsy, which should occur in fewer than 5% of procedures. With alcohol injection it is usually transient with full recovery within 1-3 months. The primary disease can cause nerve damage in both benign and malignant conditions.
After exclusion of anaplastic carcinoma, prognosis for thyroid disease is excellent.
Further reading & references
- Kelley DJ; Thyroid, Evaluation of Solitary Thyroid Nodule, Medscape, Dec 2011
- Dean DS, Gharib H; Epidemiology of thyroid nodules. Best Pract Res Clin Endocrinol Metab. 2008 Dec;22(6):901-11.
- Bomeli SR, LeBeau SO, Ferris RL; Evaluation of a thyroid nodule. Otolaryngol Clin North Am. 2010 Apr;43(2):229-38, vii.
- Guidelines for the management of thyroid cancer, British Thyroid Association and Royal College of Physicians (2007)
- Mehanna HM, Jain A, Morton RP, et al; Investigating the thyroid nodule. BMJ. 2009 Mar 13;338:b733. doi: 10.1136/bmj.b733.
- Cooper DS, Doherty GM, Haugen BR, et al; Revised American Thyroid Association management guidelines for patients with Thyroid. 2009 Nov;19(11):1167-214.
- Neck lump, Prodigy (February 2010)
- Helling TJ; Thyroid-hormone-suppressive therapy in benign thyroid nodules. Lancet. 2003 Mar 29;361(9363):1137.
|Original Author: Dr Hayley Willacy||Current Version: Dr Hayley Willacy||Peer Reviewer: Prof Cathy Jackson|
|Last Checked: 20/02/2012||Document ID: 12145 Version: 4||© EMIS|
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