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Thyroid Cyst

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) [7].

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 [8], should the cyst be within or underneath the level of the superior thoracic aperture.

Malignant Pleural Effusion
  • The agent was initially used for chemotherapy in patients with lung cancer or stomach cancer and to reduce malignant pleural effusions or ascites [ 6 ].[e-ultrasonography.org]
Thyroid Nodule
  • Biochemical examination of thyroid cyst fluid may be of value for the clinician to evaluate the nature of thyroid nodules. The potential benefits of thyroid cyst fluid examination warrant further investigation in patients with thyroid nodules.[ncbi.nlm.nih.gov]
  • The pathogenesis of cystic thyroid nodules is incompletely understood.[ncbi.nlm.nih.gov]
  • We present an interesting case report from a patient with a history of desmoplastic malignant melanoma (MM), who presented with a thyroid nodule.[ncbi.nlm.nih.gov]
  • Although, initial presentations are usually diffuse goiter and hypothyroidism, subsequently they may develop thyroid nodules and or thyroid cancer.[ncbi.nlm.nih.gov]
  • When Is Surgery Necessary For Thyroid Nodules & Cysts? There are only a few occasions when surgery is necessary to remove a thyroid nodule or cyst: 1. When the thyroid nodule or cyst is malignant.[naturalendocrinesolutions.com]
  • FNAC of the right lobe revealed a picture similar to adenomatous goiter. A subtotal thyroidectomy was performed and the histopathologic report was suggestive of multinodular goiter with dystrophic calcification.[ncbi.nlm.nih.gov]
  • The VEGF concentration in cyst fluid of patients with adenomatous goiter was significantly higher (P 0.05) than that in thyroid nodules with cystic degeneration.[ncbi.nlm.nih.gov]
  • The most common cause of a goiter is when people do not have enough iodine in their diet. In addition, thyroid nodules may cause goiter (multinodular goiter). A thyroid cyst is different.[enotes.com]
  • More info Thyroid Nodules and Goiters 101: No Surgery for Benign Goiter Nodules Thyroid Nodules and Goiters 101: No Surgery for Benign Goiter Nodules Simple Goiter: Not After All Need Surgery.[thyroidnosurgery.com]
  • A patient is described who presented with sudden collapse due to acute respiratory failure caused by tracheal compression from a thyroid cyst. He made a complete recovery and the cyst was electively excised two weeks later.[ncbi.nlm.nih.gov]
  • A cyst in the upper pole of the left lobe of thyroid appeared collapsed and contained debris, suggesting recent haemorrhage. Fig. 1 Ultrasound images of right (above) and left (below) thyroid gland showing cystic changes and debris within cysts.[ckj.oxfordjournals.org]
  • While the needle was kept in the cystic cavity, the evacuation syringe was replaced with a syringe with 96% ethanol which was slowly instilled into the collapsed cavity.[austinpublishinggroup.com]
  • Cyst may collapse, thereby becoming less echogenic on ultrasound, thereby possibly being undersampled in later passes due to loss of visualization of the lesion.[incytepathology.wordpress.com]
  • Although the mechanism of action of OK-432 sclerotherapy is not clearly understood, it is known that the collapse and adhesion of the cystic wall occur after the absorption of the injected OK- 432 solution.[e-ultrasonography.org]
  • The culture outcome was Propionibacterium acnes, which was rich in saliva and one of the pathogens causing periodontitis and gingivitis. After adequate antimicrobial therapy, the abscess gradually diminished.[ncbi.nlm.nih.gov]


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. 

Multilocular Cyst
  • Indications for Sclerotherapy With respect to efficacy, sclerotherapy has been found to have better results in the case of unilocular cysts than in the case of multilocular cysts and has proven more effective for lymphatic malformation than for ranula[e-ultrasonography.org]


The key to proper treatment of newly-diagnosed thyroid nodules is their meticulous examination, based on the 5 following procedures:

  • Medical history
  • Clinical examination
  • TSH levels (plasma)
  • Ultrasonography
  • FNA biopsy

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 [9]. 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 [10]. 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 [11].

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 [12]. 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 [2]. 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 [3]. 

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 [4] [5]. 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 [6].

Sex distribution
Age distribution


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% [1]. 

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.

Patient Information

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.



  1. Lee MJ, Kim EK, Kwak JY, Kim MJ. Partially cystic thyroid nodules on ultrasound: probability of malignancy and sonographic differentiation. Thyroid. 2009 Apr;19(4):341-6.
  2. Frates MC, Benson CB, Doubilet PM, et al. Prevalence and distribution of carcinoma in patients with solitary and multiple thyroid nodules on sonography. J Clin Endocrinol Metab. 2006;91(9):3411.
  3. Alexander EK, Heering JP, Benson CB, et al. Assessment of nondiagnostic ultrasound-guided fine needle aspirations of thyroid nodules. J Clin Endocrinol Metab. 2002;87(11):4924.
  4. Mehanna HM, Jain A, Morton RP, et al. Investigating the thyroid nodule. BMJ. 2009 Mar 13;338:b733.
  5. Knox MA. Thyroid nodules. Am Fam Physician. 2013 Aug 1;88(3):193-6.
  6. Gupta A, Ly S, Castroneves LA, et al. A standardized assessment of thyroid nodules in children confirms higher cancer prevalence than in adults. J Clin Endocrinol Metab. 2013 Aug;98(8):3238-45.
  7. Tan GH, Gharib H. Thyroid incidentalomas: management approaches to nonpalpable nodules discovered incidentally on thyroid imaging. Ann Intern Med. 1997;126(3):226.
  8. Massoll N, Nizam MS, Mazzagerri EL. Cystic thyroid nodules: Diagnostic and therapeutic dilemmas. The Endocrinologist. 2002;12:185.
  9. Layfield LJ, Cibas ES, Gharib H, Mandel SJ. Thyroid aspiration cytology: current status. CA Cancer J Clin. 2009 Mar-Apr. 59(2):99-110.
  10. Raparia K, Min SK, Mody DR, et al. Clinical outcomes for "suspicious" category in thyroid fine-needle aspiration biopsy: patient's sex and nodule size are possible predictors of malignancy. Arch Pathol Lab Med. 2009 May. 133(5):787-90. 
  11. Gul K, Ozdemir D, Korukluoglu B, et al. Preoperative and postoperative evaluation of thyroid disease in patients undergoing surgical treatment of primary hyperparathyroidism. Endocr Pract. 2010 Jan-Feb. 16(1):7-13.
  12. Treece GL, Georgitis WJ, Hofeldt FD. Resolution of recurrent thyroid cysts with tetracycline instillation. Arch Intern Med. 1983 Dec;143(12):2285-7.

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Last updated: 2017-08-09 17:28