Thyroid nodule

Thyroid nodule
ENT surgery, oncology

Thyroid nodules are

.

Signs and symptoms

Often these abnormal growths of thyroid tissue are located at the edge of the thyroid gland and can be felt as a lump in the throat. When they are large, they can sometimes be seen as a lump in the front of the neck.^{[citation needed]}

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.^[3]

Diagnosis

After a

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 physician during the course of a health examination or fortuitously discovered during the investigation of an unrelated condition.[8]

Workup of incidental nodules

Suggested workups by nodule characteristics

Features	Workup
High PET signal or Local invasiveness or Suspicious lymph nodes	Very likely ultrasonography
Multiple nodules	Likely ultrasonography
Solitary nodule in person younger than 35 years old	Likely ultrasonography if at least 1 cm large in adults, or for any size in children None needed if less than 1 cm in adults
Solitary nodule in person at least 35 years old	Likely ultrasonography if at least 1.5 cm large None needed if less than 1.5 cm

Ultrasound

The TI-RADS (Thyroid Imaging Reporting and Data Systems) are sonographic classification systems which describe the suspicious findings of thyroid nodules.[12] It was first proposed by Horvath et al.,^[13] based on the BI-RADS (Breast Imaging Reporting and Data System) concept. Several systems were subsequently proposed and adopted by international scientific societies. Their main aims are to characterize the risk of malignancy of nodules to better select nodules to submit to fine-needle aspiration cytology.^[14] Another imaging modality, which is ultrasound elastography, is also useful in diagnosing thyroid malignancy especially for follicular thyroid cancer. However, it is limited by the presence of adequate amount of normal tissue around the lesion, calcified shell around a nodule, cystic nodules, coalescent nodules.^[15]

Fine needle biopsy

The Bethesda System for Reporting Thyroid Cytopathology is the system used to report whether the thyroid cytological specimen is benign or malignant. It can be divided into six categories:

Bethesda system

Category	Description	Risk of malignancy[18]	Recommendation[18]
I	Non diagnostic/unsatisfactory	–	Repeating FNAC with ultrasound-guidance in more than 3 months
II	Benign (colloid and follicular cells)	0–3%	Clinical follow-up
III	Atypia of undetermined significance (AUS) or follicular lesion of undetermined significance (FLUS) (follicular or lymphoid cells with atypical features)	5–15%	Repeating FNAC
IV	Follicular nodule/suspicious follicular nodule (cell crowding, micro follicles, dispersed isolated cells, scant colloid)	15–30%	Surgical lobectomy
V	Suspicious for malignancy	60–75%	Surgical lobectomy or near-total thyroidectomy
VI	Malignant	97–99%	Near-total thyroidectomy

Blood tests

]

Other imaging

A thyroid scan using a radioactive iodine uptake test can be used in viewing the thyroid.^[19] A scan using iodine-123 showing a hot nodule, accompanied by a lower than normal TSH, is strong evidence that the nodule is not cancerous, as most hot nodules are benign.^{[citation needed]}

Computed tomography of the thyroid plays an important role in the evaluation of thyroid cancer.^[20] CT scans often incidentally find thyroid abnormalities, and thereby practically becomes the first investigation modality.^[20]

Malignancy

Only a small percentage of lumps in the neck are malignant (around 4 – 6.5%^[21]), and most thyroid nodules are benign colloid nodules.

There are many factors to consider when diagnosing a malignant lump. Trouble swallowing or speaking, swollen cervical lymph nodes or a firm, immobile nodule are more indicative of malignancy, whereas a family history of autoimmune disease or goiter, thyroid hormonal dysfunction or a soft, painful nodule are more indicative of benignancy.^{[citation needed]}

The prevalence of cancer is higher in males, patients under 20 years old or over 70 years old, and patients with a history of head and neck irradiation or a family history of thyroid cancer.^[22]

Solitary thyroid nodule

Risks for cancer

Solitary

to the head and neck. Most common cause of solitary thyroid nodule is benign

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.^{[citation needed]}

Signs and symptoms

Worrisome sign and symptoms include voice hoarseness, rapid increase in size, compressive symptoms (such as dyspnoea or dysphagia) and appearance of lymphadenopathy.^{[citation needed]}

Investigations

• TSH – A thyroid-stimulating hormone level should be obtained first. If it is suppressed, then the nodule is likely a hyperfunctioning (or "hot") nodule. These are rarely malignant.
• FNAC – fine
  needle aspiration cytology is the investigation of choice given a non-suppressed TSH.^[25][26]
• Imaging –
  radioiodine
  scanning.

Thyroid scan

85% of nodules are cold nodules, and 5–8% of cold and warm nodules are malignant.^[27]

5% of nodules are hot. Malignancy is virtually non-existent in hot nodules.^[28]

Surgery

Surgery (thyroidectomy) may be indicated in the following instances:

• Reaccumulation of the nodule despite 3–4 repeated FNACs
• Size in excess of 4 cm in some cases
• Compressive symptoms
• Signs of malignancy (vocal cord dysfunction, lymphadenopathy)
• Cytopathology that does not exclude thyroid cancer

Minimally-invasive procedures

Non-surgical, minimally invasive ultrasound-guided techniques are now being used for the treatment of large, symptomatic nodules. They include percutaneous ethanol injection, laser thermal ablation, radiofrequency ablation, high intensity focused ultrasound (HIFU), and percutaneous microwave ablation.^[29]

HIFU has recently proved its effectiveness in treating benign thyroid nodules. This method is noninvasive, without general anesthesia and is performed in an ambulatory setting. Ultrasound waves are focused and produce heat enabling to destroy thyroid nodules.^[30] Focused ultrasounds have been used to treat other benign tumors, such as breast fibroadenomas and fibroid disease in the uterus.^{[citation needed]}

Treatment

Levothyroxine (T4) is a prohormone that peripheral tissues convert to the primary active thyroid hormone, triiodothyronine (T3). Hypothyroid patients normally take it once per day.

Autonomous thyroid nodule

An autonomous thyroid nodule or "hot nodule" is one that has thyroid function independent of the

See also

• Thyroid adenoma

References

External links