| Thyroid nodule | |
|---|---|
| Classification and external resources | |
| ICD-9 | 241.0 |
| DiseasesDB | 5332 |
| eMedicine | med/3224 |
| MeSH | D016606 |
Thyroid nodules are lumps which commonly arise within an otherwise normal thyroid gland.[1] They indicate a thyroid neoplasm, but only a small percentage of these are thyroid cancers.
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Often these abnormal growths of thyroid tissue are located at the edge of the thyroid gland so they can be felt as a lump in the throat. When they are large or when they occur in very thin individuals, they can even sometimes be seen as a lump in the front of the neck.
Sometimes a thyroid nodule presents as a fluid-filled cavity (called a thyroid cyst). Often, solid components are mixed with the fluid. Thyroid cysts most commonly result from degenerating thyroid adenomas, which are benign, but they occasionally contain malignant solid components.[2]
After a nodule is found during a physical examination, a referral to an endocrinologist, a thyroidologist or otolaryngologist may occur. Most commonly an ultrasound is performed to confirm the presence of a nodule, and assess the status of the whole gland. Measurement of thyroid stimulating hormone and anti-thyroid antibodies will help decide if there is a functional thyroid disease such as Hashimoto's thyroiditis present, a known cause of a benign nodular goiter.[3] Fine needle biopsy for histopathology is also used.[4][5]
Thyroid nodules are extremely common in young adults and children. Almost 50% of people have had one, but they are usually only detected by a GP during the course of a health examination, or through a different affliction.
One approach used to determine whether the nodule is malignant is the fine needle biopsy (FNB),[6] which some have described as the most cost-effective, sensitive and accurate test. [7]
[8] FNB or ultrasound-guided FNA usually yields sufficient thyroid cells to assess the risk of malignancy, although in some cases, the suspected nodule may need to be removed surgically for pathological examination.
Rarely, a biopsy is done using a large cutting needle, so that a piece of nodule capsule can be obtained.
Blood or imaging tests may be done prior to or in lieu of a biopsy. The possibility of a nodule which secretes thyroid hormone (which is less likely to be cancer) or hypothyroidism is investigated by measuring thyroid stimulating hormone (TSH), and the thyroid hormones thyroxine (T4) and triiodothyronine (T3).
Tests for serum thyroid autoantibodies are sometimes done as these may indicate autoimmune thyroid disease (which can mimic nodular disease).
The blood assays may be accompanied by ultrasound imaging of the nodule to determine the position, size and texture, and to assess whether the nodule may be cystic (fluid filled). Also suspicious findings in a nodule are hypoechoic,[9] irregular borders, microcalcifications, or very high levels of blood flow within the nodule. Less suspicious findings in benign nodules include, hyperechoic, comet tail artifacts from colloid, no blood flow in the nodule and a halo, or smooth border.
Some clinicians will also request technetium (Tc) or radioactive iodine (I) imaging of the thyroid. An 123I scan showing a hot nodule, accompanied by a lower than normal TSH, is strong evidence that the nodule is not cancerous.
Only a small percentage of lumps in the neck are malignant, and most thyroid nodules are benign.
There are many factors to consider when diagnosing a malignant lump.
If the patient is a smoker, the chances of malignancy are considerably higher. When coupled with difficulty swallowing or breathing, this may be a symptom of a serious condition and requires speedy medical attention.
Solitary thyroid nodules are more common in females yet more worrisome in males. Other associations with neoplastic nodules are family history of thyroid cancer and prior radiation to the head and neck.
Radiation exposure to the head and neck may be for historic indications such as tonsillar and adenoid hypertrophy, "enlarged thymus", acne vulgaris, or current indications such as Hodgkin's lymphoma. Children living near the Chernobyl nuclear power plant during the catastrophe of 1986 have experienced a 60-fold increase in the incidence of thyroid cancer. Thyroid cancer arising in the background of radiation is often multifocal with a high incidence of lymph node metastasis and has a poor prognosis.
Worrisome sign and symptoms include voice hoarseness, rapid increase in size, compressive symptoms (such as dyspnoea or dysphagia) and appearance of lymphadenopathy.
Surgery should be performed in the following instances
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