A thyroid cyst is a dilated area of the thyroid which is either exclusively filled with fluid, or contains both fluid and solid parts.
Thyroid cysts most often remain asymptomatic and are detected during an imaging process such as ultrasonography or computerized tomography, performed on the neck area for irrelevant reasons. This is why thyroid nodules are often termed "thyroid incidentalomas" (discovered incidentally) .
In some cases, nodules produce symptomatology due to spontaneous hemorrhage of smaller or bigger extent. Limited hemorrhage causes pain in the thyroid region and difficulty swallowing. Should the hemorrhage be of a greater extent, alienation of the voice tone can occur in the sense of a hoarser voice and paralysis of the vocal chords. The airway may also be affected , should the cyst be within or underneath the level of the superior thoracic aperture.
Thyroid function tests (TFTs) are the first screening examination that should be performed according to the British Thyroid Association's recommendations. Patients whose TFT produces an abnormal outcome but exhibit no other abnormal characteristics will be assessed by an endocrinologist. Guidelines dictate that patients with normal TFTs and newly-discovered thyroid swelling should be evaluated promptly by a surgeon or endocrinologist.
As a second step, patients highly benefit from an ultrasonographic evaluation, which will outline the characteristics of a nodule and determine which patients require an FNA. Finally, an FNA is carried out with the help of ultrasonographic monitoring and the tissue harvested can be histologically examined in order to analyze the tissue type. Carcinoembryonic antigen (CEA) and basal plasma calcitonin are measured solely in cases where medullary thyroid malignancy is probable and CT/MRI scans help diagnose regional and mediastinal enlarged lymph nodes.
The key to proper treatment of newly-diagnosed thyroid nodules is their meticulous examination, based on the 5 following procedures:
After these steps are concluded, the patient can be categorized under of the categories established by the Bethesda conference, based on the outcome of the biopsy . Thus, any patient with a histologically confirmed malignancy and those affected by a follicular neoplasm (30% risk of cancer) require surgical evaluation. Cancerous lymphomas and anaplastic carcinomas are usually not assessed by surgeons, since the first requires no surgical treatment and the second does not benefit from it.
One of the categorizations of the Bethesda set of criteria involves the presence of atypical cells, whose presence cannot rule out malignancy but simultaneously fails to confirm it. Should such a diagnosis be set by an FNA, patients who also exhibit ultrasonographic traits compatible to cancer (hyperperfusion, calcifications, hypoechogenicity) need to consult a surgeon . If, on the other hand, the patient's nodules display no characteristics compatible with malignancy, FNA is repeated after 3-6 months. Physicians should keep in mind that repeated FNAs with no accurate diagnostic findings indicate that a patient should ultimately consult a surgeon .
Nodules that are found to be non-cancerous after an FNA biopsy do not require any surgical intervention and are monitored with a US scan every 6 to 18 months. A repetition of the FNA is recommended by some clinicians after 6 to 12 months as a precautionary measure, to eliminate a possible false negative result of the first biopsy, although the possibility is low. Patients with symptomatology that includes neck pain or dysphagia should also be referred to a surgeon, despite a negative for malignancy FNA result.
Exclusively cystic lesions can be treated with aspiration, which is repeated if the cyst persists. Thyroid hormone has been administered to patients to prevent re-emerging cysts, with no actual, reliable results . Cysts that re-emerge should be evaluated again, as they may in fact be complex cysts and contain solid matter as well; those cysts need to be surgically excised and histologically examined, although the results are often unsatisfactory as for their characterization. Nodule sclerosing with the aid of ethanol or tetracycline (100mg/ml) has shown some positive results but remains rather unused.
Thyroid cysts are a common finding amongst the adult population. The majority of them are non-cancerous and many also require no treatment. Careful evaluation will allow for the detection and excision of malignancies.
The causes of thyroid cysts still remain rather unclear; their development has however been strongly associated with radiation exposure and aging. Nodules also display an inheritance pattern, where whole families exhibit cysts at various points of their lives, without any precise genetic information being available.
Nodules located on the thyroid region constitute symptomatology that is compatible with many thyroid diseases. Most frequently, thyroid cysts are caused by hyperplastic processes of the gland, Hashimoto's thyroiditis or subacute thyroiditis.
Cystic nodules, namely cysts that consist exclusively of liquid matter, are rare, according to a 1985 study that evaluated 3,483 nodules >10mm and discovered only 7 cystic ones . Other studies assessed over 1,000 patients with the aid of ultrasound and fine-needle aspiration (FNA), half of whom had partly cystic nodules, with 3/4 of the initial sample consisting of more than 75% liquid content .
Thyroid nodules are commonly (40%) detected by chance via ultrasonographic imaging, with autopsical records being in agreement with the number. The vast majority of these nodules are non-malignant  . Generally, approximately 7% of the adult population is believed to have thyroid cysts, whether complex or cystic. Adolescents and pediatric patients exhibit thyroid nodules at a diminished frequency (app. 1.5%); the possibility of an underlying malignancy is, however, increased in the small percentage of those individuals who do present with thyroid cysts .
Non-malignant thyroid cysts are histologically characterized as fetal, follicular, embryonal, Hurthle or papillary adenomas. Adenomas display few mitoses and precise architecture, without perfusion signs or lymphatic contents. They are typically encased in an fibrous envelope. It is known that every nodule will eventually contain some fluid material; this has been attributed to a partial necrosis of the tissue contained within a mass, which liquidates to become the cystic part of a nodule. Colloid nodules exhibit a high frequency in a resulting cyst formation.
There is no way to prevent the formation of a thyroid cyst.
There are two types of thyroid cysts, exclusively cystic ones and complex ones. Nodules are termed cystic when no solid matter is detected in them; complex nodules are composed of fluids and solid substance. Thyroid cysts may enlarge gradually or spontaneously, with a spontaneous manifestation of a greatly enlarged cyst usually being a result of traumatization of a smaller one.
The essential difference between complex and cystic nodules is their nature of their components; however, a further difference is their risk of harboring a malignancy. Research data has shown that nodules, half of whose contents were solid, exhibited a 20% risk of cancerous tumor. The less solid matter contained in a nodule, the less risk involved for a potential malignancy, estimated at around 5% .
Thyroid nodules, whether cystic or complex, are a frequent phenomenon and usually asymptomatic. If they expand greatly in size, they may cause symptoms such as neck pain, hoarseness and dysphagia. Cystic masses are diagnosed with the help of ultrasonography; thyroid aspiration biopsy can eliminate the possibility of malignancy, should a cyst contain plenty of solid contents.
As far as treatment is concerned, it depends on the accurate diagnosis of a mass as a malignant or non-malignant structure. Benign cysts that produce no symptomatology often receive no treatment, but patients are required to adhere to a follow-up plan to allow for the detection of alterations. Drug administration for the shrinking of a cyst is implemented by some physicians; lastly, malignancies are surgically removed.
Thyroid cyst is a term used to describe dilated areas of the thyroid which contain solely fluid (cystic nodules) or liquid and solid contents (complex nodules). Thyroid nodules are very common amongst the population and the less solid material they are composed of, the less risk of malignancy is involved. Their causes are not exactly definable, but they can be a result of hypothyroidism, Hashimoto's thyroiditis and iodine deficiency amongst others.
Additionally, various risk factors have been established for the development of thyroid nodules. Mayo Clinic has produced a list of people with a higher probability of exhibiting such structures; the list includes patients whose relatives also displayed such cysts, other thyroid disorders, female gender, older age and people who have been treated with radiation to the area of the neck for another condition.
Nodules do not usually produce symptoms. Some patients may feel a mass on their neck, neck pain or discomfort. Bigger cysts may lead to breathing problems or difficulty in swallowing and may even account for a change in the tone of a patient's voice. In general, thyroid nodules are detected incidentally in an examination of the neck carried out for other conditions.
Thyroid cysts are accurately assessed via biopsy. Depending on the outcome, the cyst may be excised or simply monitored through ultrasonography and/or biopsy at regular intervals. Some patients may also receive treatment with a drug, levothyroxine, which inhibits thyroid tissue growth and therefore shrinks the nodules. Consult an endocrinologist of GP if you observe any new symptoms. Some nodules may need to be biopsied repeatedly and may ultimately require surgical intervention. Generally, patients should bear in mind that there is no single treatment plan for those who are affected by thyroid cysts and each scheme is indeed individualized.