Also known as thyroid nodules, they are elevated areas of tissue or fluid that commonly arise within an otherwise normal thyroid gland.
They can be hyperplasia or thyroid neoplasia , but only a small percentage of the latter are thyroid cancers .
These thyroid cysts represent regions of the thyroid fluid-filled and enlarged that can be small (less than 1 cm) or quite large, and sometimes arise very suddenly.
A cyst, by definition, contains fluid.
Thyroid nodules that are completely cystic, in which case there are no detectable solid components within the fluid, are almost routinely benign.
Thyroid cysts that are more complex and contain both solid and fluid components are called in many different ways, including complex cysts, mixed echogenic nodules, etc.
Complex cysts, like any other thyroid nodule, should be evaluated by experts in ultrasound and thyroid cytopathology when criteria for biopsy or cell sampling are indicated.
Cystic nodules may remain stable, sometimes they become smaller and at some point they continue to expand. Some cysts can expand rapidly due to bleeding or bleeding inside the cyst.
Rapidly expanding cysts can become symptomatic, producing a noticeable lump in the neck, pain, difficulty swallowing and very rarely change in the voice.
Cysts that are completely filled with fluid have a much lower risk of thyroid cancer compared to cysts that have solid components.
The diagnosis of a cystic thyroid lesion can be made at the time of ultrasound or after a fine-needle biopsy when fluid is obtained from the thyroid cyst.
Spontaneous resolution of a thyroid cyst is rare, but it can occur in up to 15% of cases. Most large cysts or complex cysts should be aspirated with a fine needle to rule out the possibility of malignancy.
Ultrasound-guided needle biopsies of a complex cystic nodule are necessary to ensure that the biopsy material contains thyroid cells, and not just cystic fluid.
Only these cells of the solid component will provide the necessary information, regardless of whether the cystic nodule is relevant or not.
Small, asymptomatic nodules are common and many people are unaware that they have them. But nodules that grow or produce symptoms may eventually need medical attention. Goiters can have nodules or be diffuse.
For the evaluation of a partially cystic nodule, the risk of cancer seems proportional to the degree to which the nodule also contains solid components.
Partially cystic nodules that contain at least 50% solid tissue have a risk of malignancy that is similar to nodules of equal size that are completely solid.
On the other hand, largely cystic nodules with smaller solid components have a much lower risk of thyroid cancer, usually less than 5%.
Pure thyroid cysts can be treated in several ways. More often, pure thyroid cysts that measure 3 cm or less are simply observed and monitored for changes.
Alternative management approaches for thyroid cysts are many, including the aspiration and instillation of ethanol or other ablative approaches. Simply aspirating thyroid cysts is largely ineffective with a very rapid return of cyst fluid.
Thyroid surgery effectively removes thyroid cysts, but is not commonly used unless there are multiple large thyroid cysts and have become evident or symptomatic for the thyroid patient.
Thyroid nodules are common, and a large proportion have mixed cystic and solid components. In some studies, a nodule is called a cyst only if it is predominantly cystic on ultrasound, but in others the term is applied to predominantly solid nodules but with small areas of cystic degeneration.
Therefore, depending on the criteria used, up to 50 percent of solitary thyroid nodules are cystic.
Adequate evaluation and treatment of patients with cystic thyroid nodules is a controversial area.
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 on the front of the neck.
Sometimes, a thyroid nodule appears as a fluid-filled cavity called a thyroid cyst.
Solitary thyroid nodules are more common in women and even more worrisome in men. Other associations with neoplastic nodules are a family history of thyroid cancer and previous radiation to the head and neck.
The most common cause of the solitary thyroid nodule are benign colloid nodules and the second most common cause is follicular adenoma.
Exposure to radiation in the head and neck may be due to historical indications, such as tonsillar and adenoidal hypertrophy, the “enlarged thymus”, acne vulgaris or current indications, such as Hodgkin’s lymphoma .
Children living near the Chernobyl nuclear power plant during the 1986 catastrophe have experienced a 60-fold increase in the incidence of thyroid cancer.
Thyroid cancer that arises in the background of radiation is often multifocal with a high incidence of lymph node metastasis and has a poor prognosis.
Signs and symptoms
85% of the nodules are cold nodules and 5-8% of the cold and hot nodules are malignant.
5% of the nodules are hot. Malignancy is practically non-existent in hot nodules.
After finding a nodule during a physical examination, an endocrinologist or an otolaryngologist can be referred. Most commonly, an ultrasound is performed to confirm the presence of a nodule and assess the status of the entire gland.
The measurement of thyroid stimulating hormone and thyroid antibodies will help to decide if there is functional thyroid disease such as Hashimoto’s thyroiditis, a known cause of benign nodular goiter. A fine needle biopsy is also used for histopathology.
Thyroid nodules are extremely common in young adults and children. Almost 50% of people have had one, but usually only a doctor detects it during a health examination or is discovered accidentally during the investigation of an unrelated condition.
The American College of Radiology recommends the following studies for thyroid nodules as incidental imaging findings on computed tomography, magnetic resonance imaging, or positron emission tomography computed tomography, other tests include:
You are likely to be asked to swallow while your doctor examines your thyroid because a nodule in your thyroid gland will usually move up and down during swallowing.
Ultrasound is useful as the first line of noninvasive research to determine the size, texture, position and vascularity of a nodule, access metastasis of the lymph nodes in the neck and guide cytology by fine needle aspiration or biopsy.
The high frequency transducer (7-12 MHz) is used to scan the thyroid nodule, while taking cross and longitudinal sections during the examination.
Suspect findings in a nodule are hypoechoic, poorly defined margins, absence of peripheral halo or irregular margin, fine punctate microcalcifications, presence of solid nodules, high levels of irregular blood flow within the nodule or “sign higher than width” (anterior diameter) -posterior is greater than the transverse diameter of a nodule).
The characteristics of the benign lesion are: hyperechoic, with thick calcifications, dysmorphic or curvilinear, artifact of the tail of the comet (reflection of a highly calcified object), absence of blood flow in the nodule and presence of cystic nodule (filled with fluid) .
However, the presence of solitary or multiple nodules is not a good predictor of malignancy. The malignancy is only diagnosed when the ultrasound findings and the cytology report by fine needle aspiration suggest malignancy.
Another imaging modality, which is ultrasound elastography, is also useful for diagnosing malignant thyroid neoplasia, especially for follicular thyroid cancer.
However, it is limited by the presence of an adequate amount of normal tissue around the lesion, a calcified shell around a nodule, cystic nodules, coalescing nodules.
Fine needle biopsy:
End-needle aspiration cytology is an economical, simple and safe method to obtain cytological samples for diagnosis by using a needle and a syringe.
The procedure, which takes place in your doctor’s office, takes about 20 minutes and presents few risks. Often, your doctor will use ultrasound to help guide the needle placement. The samples are sent to a laboratory and analyzed under a microscope.
The Bethesda system to inform the cytoplasmic thyroid is the system used to inform if the cytological thyroid sample is benign or malignant. It can be divided into six categories:
Not diagnostic / unsatisfactory. With zero risk of malignancy. Repeat cytology by fine needle aspiration with ultrasound guidance in more than 3 months.
Benign (colloidal and follicular cells). With 0 – 3% risk of malignancy. Clinical follow-up is recommended.
Attypia of undetermined significance / follicular injury of undetermined significance (follicular or lymphoid cells with atypical features). With 5 – 15% risk of malignancy. Repeat cytology by fine needle aspiration.
Follicular nodule / suspicious follicular nodule (crowding of cells, micro follicles, isolated scattered cells, sparse colloid). With 15 – 30% risk of malignancy. Surgical lobectomy is recommended.
Suspect for malignancy. With 60 – 75% risk of malignancy. Surgical lobectomy or almost total thyroidectomy
Malignant with 97 – 99% risk of malignancy. Near-total thyroidectomy
Blood tests can be done before or in place of a biopsy. The possibility of a nodule that secretes thyroid hormone (which is less likely to be cancer) or hypothyroidism is investigated by measuring thyroid stimulating hormone (TSH) and thyroid hormones thyroxine (T4) and triiodothyronine (T3).
Serum thyroid autoantibody tests are sometimes performed because they may indicate an autoimmune thyroid disease (which may mimic a nodular disease).
The nodules detected by the thyroid scanners are classified as cold, hot or warm. If a nodule is composed of cells that do not produce thyroid hormone (do not absorb iodine), then it will appear “cold” on the X-ray film.
A nodule that is producing too much hormone will appear darker and is called “hot”.
In some cases, your doctor may recommend a thyroid scan to help evaluate thyroid nodules, a thyroid test may be used using a radioactive iodine uptake test to see the thyroid.
During this test, an isotope of radioactive iodine is injected into a vein in your arm. Then he lies down on a table while a special camera produces an image of his thyroid on a computer screen.
The nodules that produce excess thyroid hormone, called hot nodules, appear in the scanner because they absorb more isotopes than normal thyroid tissue and on an iodine scan will show a warm nodule, accompanied by a lower-than-normal thyroid stimulating hormone, is a strong evidence that the nodule is not cancerous, since most hot nodules are benign.
Cold nodules do not work and appear as defects or holes in the scan, but some cold nodules are cancerous.
The disadvantage of a thyroid examination is that it can not distinguish between benign and malignant cold nodules; it should not, in general, be used as the sole basis for recommending nodule treatment, including thyroid surgery.
85% of the thyroid nodules are cold, 10% are warm and 5% are hot. Remember that 85% of cold nodules are benign, 90% of warm nodules are benign and 95% of warm nodules are benign.
The duration of a thyroid scan varies, depending on the time it takes for the isotope to reach the thyroid gland. You may have some discomfort in your neck because your neck will stretch during the scan and you will be exposed to a small amount of radiation.
The evaluation of a solitary thyroid nodule should always include the history and examination of a doctor. Certain aspects of the history and physical examination will suggest a benign or malignant condition. Remember, a biopsy of some kind is the only way to know for sure.
Levothyroxine is a stereoisomer of thyroxine that degrades much more slowly and can be administered once a day in patients with hypothyroidism.
Thyroid hormone levels are usually normal in the presence of a nodule, and normal levels of thyroid hormone do not differentiate between benign and cancerous nodules.
However, the presence of hyperthyroidism or hypothyroidism favors a benign nodule (that’s why a “hot” or “hot” nodule favors a benign condition).
Thyroglobulin levels are useful tumor markers once the diagnosis of malignancy has been made, but they are not specific with respect to the differentiation between a benign thyroid nodule and a cancerous one.
Ultrasound accurately determines the volume, number and size of nodules of the thyroid gland, separates the thyroid from the non-thyroid masses, helps guide the fine-needle biopsy when necessary and can identify solid nodules up to 3 mm and cystic nodules up to 2 mm.
If a biopsy shows that you have a benign thyroid nodule, your doctor may suggest simply observing your condition. This usually means having a physical examination and thyroid function tests at regular intervals.
It is also likely that another biopsy is done if the nodule grows. If a benign thyroid nodule remains unchanged, you may never need treatment.
Thyroid hormone suppression therapy:
Therapy with levothyroxine is a subject of debate. There is no clear evidence that the treatment consistently reduces the nodules or even that small benign nodules are needed that shrink.
Surgery (thyroidectomy) may be indicated in the following cases:
- Reaccumulation of the nodule despite 3-4 cytologies by repeated fine needle aspiration.
- Size greater than 4 cm in some cases.
- Compressive symptoms.
- Signs of malignancy (dysfunction of the vocal cords, lymphadenopathy).
- Cytopathology that does not exclude thyroid cancer.
An alternative that uses high intensity focused ultrasound or high intensity focused ultrasound has recently demonstrated its effectiveness in the treatment of benign thyroid nodules.
This method is non-invasive, without general anesthesia and is performed in an outpatient setting. The ultrasound waves are focused and produce heat, which allows to destroy the thyroid nodules.
Focused ultrasounds have been used to treat other benign tumors, such as breast fibroadenomas and fibroid disease in the uterus.
The following characteristics favor a benign thyroid nodule:
- Family history of Hashimoto’s thyroiditis.
- Family history of benign thyroid nodule or goiter.
- Symptoms of hyperthyroidism or hypothyroidism.
- Pain or sensation associated with a nodule.
- A smooth and smooth mobile nodule.
- Multinodular goiter without predominant nodule (many nodules, nor a main nodule).
- “Hot” nodule on the thyroid scanner (produces a normal amount of hormone).
- Simple cyst in an ultrasound.
Thyroid neoplasia is a neoplasm or tumor of the thyroid. It can be a benign tumor such as thyroid adenoma, or it can be a malignancy (thyroid cancer), such as papillary, follicular, medullary or anaplastic thyroid cancer.
Most patients are between 25 and 65 years of age when they are first diagnosed; Women are more affected than men.
The estimated number of new cases of thyroid cancer in the United States in 2010 is 44,670 compared to only 1,690 deaths. Of all the discovered thyroid nodules, only about 5 percent are cancerous, and less than 3 percent of them produce deaths.
Only a small percentage of lumps in the neck are malignant (around 4 to 6.5%), and most thyroid nodules are benign colloid nodules.
There are many factors to consider when diagnosing a malignant tumor.
Problems swallowing or speaking, swollen cervical lymph nodes or a firm, immobile nodule are more indicative of malignancy, while a family history of autoimmune disease or goiter, thyroid hormone dysfunction or a tender and painful nodule are more indicative of benignity.
The prevalence of cancer is higher in men, patients younger than 20 years or older than 70 years, and patients with a history of head and neck irradiation or a family history of thyroid cancer.
The following characteristics increase the suspicion of a malignant nodule:
- Age less than 20.
- Age greater than 70
- Male gender.
- New appearance of difficulties to swallow.
- New appearance of hoarseness.
- History of external irradiation of the neck during childhood.
- Firm, irregular and fixed nodule.
- Presence of cervical lymphadenopathy (inflamed and hard lymph nodes in the neck).
- History of thyroid cancer.
- Nodule that is “cold” in the scan (shown in the image above, which means that the nodule does not produce the hormone).
- Solid or complex in an ultrasound.
Thyroid stimulating hormone : first a level of thyroid stimulating hormone must be obtained. If it is suppressed, then the nodule is probably a hyperfunctioning (or “hot”) nodule. These are rarely malignant.
Fine needle aspiration cytology: fine needle aspiration cytology is the research of choice given a non-suppressed thyroid stimulating hormone.
Images : ultrasound and gammagraphy with radioactive iodine.
Autonomic thyroid nodule
An autonomous thyroid nodule or “hot nodule” is one that has thyroid function independent of the homeostatic control of the hypothalamic-pituitary-thyroid axis (hypothalamic-pituitary-thyroid axis).
According to a 1993 article, such nodules should be treated only when they become toxic; Surgical excision (thyroidectomy), radioactive iodine therapy, or both may be used.