Thyroid nodules are
nodules (raised areas of tissue or fluid) which commonly arise within an otherwise normal
thyroid gland.
They may be
hyperplastic
Hyperplasia (from ancient Greek ὑπέρ ''huper'' 'over' + πλάσις ''plasis'' 'formation'), or hypergenesis, is an enlargement of an organ or tissue caused by an increase in the amount of organic tissue that results from cell proliferatio ...
or
tumorous, but only a small percentage of thyroid tumors are
malignant
Malignancy () is the tendency of a medical condition to become progressively worse.
Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...
. Small,
asymptomatic nodules are common, and often go unnoticed.
Nodules that grow larger or produce
symptoms may eventually need medical care. A
goitre
A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly.
Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term is ...
may have one nodule –
uninodular, multiple nodules –
multinodular, or be
diffuse
Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemical p ...
.
Signs and symptoms
Often these abnormal growths of thyroid tissue are located at the edge of the thyroid gland and can be
felt
Felt is a textile material that is produced by matting, condensing and pressing fibers together. Felt can be made of natural fibers such as wool or animal fur, or from synthetic fibers such as petroleum-based acrylic or acrylonitrile or wood ...
as a lump in the throat. When they are large, they can 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 adenoma
A thyroid adenoma is a benign tumor of the thyroid gland, that may be inactive or active (functioning autonomously) as a toxic adenoma.
Signs and symptoms
A thyroid adenoma may be clinically silent ("cold" adenoma), or it may be a functional tumo ...
s, which are benign, but they occasionally contain malignant solid components.
Diagnosis
After a
nodule is found during a physical examination, a referral to an
endocrinologist
Endocrinology (from ''endocrine'' + '' -ology'') is a branch of biology and medicine dealing with the endocrine system, its diseases, and its specific secretions known as hormones. It is also concerned with the integration of developmental events ...
, a
thyroidologist or
otolaryngologist
Otorhinolaryngology ( , abbreviated ORL and also known as otolaryngology, otolaryngology–head and neck surgery (ORL–H&N or OHNS), or ear, nose, and throat (ENT)) is a surgical subspeciality within medicine that deals with the surgical a ...
may occur. Most commonly an
ultrasound
Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...
is performed to confirm the presence of a nodule, and assess the status of the whole gland. Measurement of
thyroid stimulating hormone
Thyroid-stimulating hormone (also known as thyrotropin, thyrotropic hormone, or abbreviated TSH) is a pituitary hormone that stimulates the thyroid gland to produce thyroxine (T4), and then triiodothyronine (T3) which stimulates the metabolism of ...
and anti-thyroid antibodies will help decide if there is a functional thyroid disease such as
Hashimoto's thyroiditis
Hashimoto's thyroiditis, also known as chronic lymphocytic thyroiditis and Hashimoto's disease, is an autoimmune disease in which the thyroid gland is gradually destroyed. Early on, symptoms may not be noticed. Over time, the thyroid may enlarg ...
present, a known cause of a benign nodular
goitre
A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. A goitre can be associated with a thyroid that is not functioning properly.
Worldwide, over 90% of goitre cases are caused by iodine deficiency. The term is ...
.
Fine needle biopsy
Fine-needle aspiration (FNA) is a diagnostic procedure used to investigate lumps or masses. In this technique, a thin (23–25 gauge (0.52 to 0.64 mm outer diameter)), hollow needle is inserted into the mass for sampling of cells that, aft ...
for
cytopathology
Cytopathology (from Greek , ''kytos'', "a hollow"; , ''pathos'', "fate, harm"; and , '' -logia'') is a branch of pathology that studies and diagnoses diseases on the cellular level. The discipline was founded by George Nicolas Papanicolaou in ...
is also used.
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.
Workup of incidental nodules
The American College of Radiology The American College of Radiology (ACR), founded in 1923, is a professional medical society representing nearly 40,000 diagnostic radiologists, radiation oncologists, interventional radiologists, nuclear medicine physicians and medical physicists.
...
recommends the following workup for thyroid nodules as
incidental imaging finding
In medical or research imaging, an incidental imaging finding (also called an incidentaloma) is an unanticipated finding which is not related to the original diagnostic inquiry. As with other types of incidental medical findings, they may represe ...
s on
CT,
MRI
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
or
PET-CT
Positron emission tomography–computed tomography (better known as PET-CT or PET/CT) is a nuclear medicine technique which combines, in a single gantry, a positron emission tomography (PET) scanner and an x-ray computed tomography (CT) scan ...
:
Ultrasound
Ultrasound
Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...
imaging is useful as the first-line, non-invasive investigation in determining the size, texture, position, and vascularity of a nodule, accessing lymph nodes metastasis in the neck, and for guiding
fine needle aspiration cytology
Fine-needle aspiration (FNA) is a diagnostic procedure used to investigate lumps or masses. In this technique, a thin (23–25 gauge (0.52 to 0.64 mm outer diameter)), hollow needle is inserted into the mass for sampling of cells that, aft ...
(FNAC) or biopsy. Ultrasonographic findings will also guide the indication to biopsy and the long term follow-up. High frequency transducer (7–12 MHz) is used to scan the thyroid nodule, while taking cross-sectional and longitudinal sections during scan. Suspicious findings in a nodule are
hypoechoic, ill-defined margins, absence of peripheral
halo
Halo, halos or haloes usually refer to:
* Halo (optical phenomenon)
* Halo (religious iconography), a ring of light around the image of a head
HALO, halo, halos or haloes may also refer to:
Arts and entertainment Video games
* ''Halo'' (franch ...
or irregular margin, fine, punctate
microcalcification
Microcalcifications are tiny deposits of calcium salts that are too small to be felt but can be detected by imaging. They can be scattered throughout the mammary gland, or occur in clusters.
Microcalcifications can be an early sign of breast cancer ...
s, presence of solid nodule, high levels of irregular blood flow within the nodule
or "taller-than-wide sign" (anterior-posterior diameter is greater than transverse diameter of a nodule). Features of benign lesion are:
hyperechoic, having coarse, dysmorphic or curvilinear calcifications, comet tail artifact (reflection of a highly calcified object), absence of blood flow in the nodule, and presence of cystic (fluid-filled) nodule. However, the presence of solitary or multiple nodules is not a good predictor of malignancy. Malignancy is only diagnosed when ultrasound findings and FNAC report are suggestive of malignancy.
The TI-RADS (Thyroid Imaging Reporting and Data Systems) are sonographic classification systems which describe the suspicious findings of thyroid nodules. It was first proposed by Horvath et al., based on the
BI-RADS BI-RADS is an acronym for Breast Imaging-Reporting and Data System, a quality assurance tool originally designed for use with mammography. The system is a collaborative effort of many health groups but is published and trademarked by the American ...
(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.
Another imaging modality, which is ultrasound
elastography
Elastography is any of a class of medical imaging modalities that map the elastic properties and stiffness of soft tissue.Sarvazyan A, Hall TJ, Urban MW, Fatemi M, Aglyamov SR, Garra BSOverview of elastography–an emerging branch of medical im ...
, is also useful in diagnosing thyroid malignancy especially for
follicular thyroid cancer
Follicular thyroid cancer accounts for 15% of thyroid cancer and occurs more commonly in women over 50 years of age. Thyroglobulin (Tg) can be used as a tumor marker for well-differentiated follicular thyroid cancer. Thyroid follicular cells are ...
. However, it is limited by the presence of adequate amount of normal tissue around the lesion, calcified shell around a nodule, cystic nodules,
coalescent
''Coalescent'' is a science-fiction novel by Stephen Baxter. It is part one of the ''Destiny's Children'' series. The story is set in two main time periods: modern Britain, when George Poole finds that he has a previously unknown sister and f ...
nodules.
Fine needle biopsy
Fine Needle Aspiration Cytology
Fine-needle aspiration (FNA) is a diagnostic procedure used to investigate lumps or masses. In this technique, a thin (23–25 gauge (0.52 to 0.64 mm outer diameter)), hollow needle is inserted into the mass for sampling of cells that, aft ...
(FNAC) is a cheap, simple, and safe method in obtaining
cytological
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and ...
specimens for diagnosis by using a needle and a syringe. The indications to do FNAC are: nodules more than 1 cm with two ultrasound criteria suggestive of malignancy, nodules of any size with extracapsular extension or lymph nodes enlargement with unknown source, any sizes of nodules with history of head and neck radiation, family history of thyroid carcinoma in two or more first degree relatives, multiple endocrine neoplasia type II, and increased calcitonin levels. However, increased calcitonin levels can also be attributable to smoking, chronic alcohol consumption, usage of proton pump inhibitors, and renal failure. 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:
Blood tests
Blood 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
Thyroid-stimulating hormone (also known as thyrotropin, thyrotropic hormone, or abbreviated TSH) is a pituitary hormone that stimulates the thyroid gland to produce thyroxine (T4), and then triiodothyronine (T3) which stimulates the metabolism of ...
(TSH), and the thyroid hormones
thyroxine
File:Thyroid_system.svg, upright=1.5, The thyroid system of the thyroid hormones T3 and T4
rect 376 268 820 433 Thyroid-stimulating hormone
rect 411 200 849 266 Thyrotropin-releasing hormone
rect 297 168 502 200 Hypothalamus
rect 66 216 386 25 ...
(T4) and
triiodothyronine
Triiodothyronine, also known as T3, is a thyroid hormone. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate.
Production of T3 and its prohormone thyroxine ...
(T3).Tests for serum thyroid
autoantibodies are sometimes done as these may indicate
autoimmune
In immunology, autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other normal body constituents. Any disease resulting from this type of immune response is termed an "autoimmune disease". ...
thyroid disease (which can mimic nodular disease).
Other imaging
![Thyroid scan](https://upload.wikimedia.org/wikipedia/commons/e/e0/Thyroid_scan.jpg)
A thyroid scan using a
radioactive iodine uptake test
The radioactive iodine uptake test is a type of scan used in the diagnosis of thyroid problems, particularly hyperthyroidism. It is entirely different from radioactive iodine therapy (RAI therapy), which uses much higher doses to destroy cancerou ...
can be used in viewing the thyroid. A scan using
iodine-123
Iodine-123 (123I) is a radioactive isotope of iodine used in nuclear medicine imaging, including single-photon emission computed tomography (SPECT) or SPECT/CT exams. The isotope's half-life is 13.2230 hours; the decay by electron capture to tellu ...
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.
Computed tomography of the thyroid plays an important role in the evaluation of thyroid cancer.
[Creative Commons Attribution 4.0 International License]
/ref> CT scans often incidentally find thyroid abnormalities, and thereby practically becomes the first investigation modality.[
]
Malignancy
Only a small percentage of lumps in the neck are malignant (around 4 – 6.5%), 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.
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.
Solitary thyroid nodule
![Relative incidences of histopathologic diagnoses of solitary thyroid nodules](https://upload.wikimedia.org/wikipedia/commons/6/66/Relative_incidences_of_histopathologic_diagnoses_of_solitary_thyroid_nodules.png)
Risks for cancer
Solitary thyroid
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...
nodules are more common in females yet more worrisome in males. Other associations with neoplastic nodules are family history of thyroid cancer
Thyroid cancer is cancer that develops from the tissues of the thyroid gland. It is a disease in which cells grow abnormally and have the potential to spread to other parts of the body. Symptoms can include swelling or a lump in the neck. C ...
and prior radiation to the head and neck.
Most common cause of solitary thyroid nodule is benign colloid nodule
Colloid nodules, also known as adenomatous nodules or colloid nodular goiter are benign, noncancerous enlargement of thyroid tissue. Although they may grow large, and there may be more than one, they are not malignant and they will not spread beyon ...
s and second most common cause is follicular adenoma.
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
Chernobyl ( , ; russian: Чернобыль, ) or Chornobyl ( uk, Чорнобиль, ) is a partially abandoned city in the Chernobyl Exclusion Zone, situated in the Vyshhorod Raion of northern Kyiv Oblast, Ukraine. Chernobyl is about no ...
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.
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.
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.
* Imaging – Ultrasound
Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...
and radioiodine
There are 37 known isotopes of iodine (53I) from 108I to 144I; all undergo radioactive decay except 127I, which is stable. Iodine is thus a monoisotopic element.
Its longest-lived radioactive isotope, 129I, has a half-life of 15.7 million year ...
scanning.
Thyroid scan
85% of nodules are cold nodules, and 5–8% of cold and warm nodules are malignant.
5% of nodules are hot. Malignancy is virtually non-existent in hot nodules.
Surgery
Surgery (thyroidectomy
A thyroidectomy is an operation that involves the surgical removal of all or part of the thyroid gland. In general surgery, endocrine or head and neck surgeons often perform a thyroidectomy when a patient has thyroid cancer or some other conditio ...
) 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
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...
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.
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.
Focused ultrasounds have been used to treat other benign tumors, such as breast fibroadenomas and fibroid disease in the uterus.
Treatment
Levothyroxine
Levothyroxine, also known as -thyroxine, is a manufactured form of the thyroid hormone thyroxine (T4). It is used to treat thyroid hormone deficiency (hypothyroidism), including a severe form known as myxedema coma. It may also be used to tre ...
(T4) is a prohormone
A prohormone is a committed precursor of a hormone consisting of peptide hormones synthesized together that has a minimal hormonal effect by itself because of its expression-suppressing structure, often created by protein folding and binding additi ...
that peripheral tissues convert to the primary active thyroid hormone, triiodothyronine
Triiodothyronine, also known as T3, is a thyroid hormone. It affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate.
Production of T3 and its prohormone thyroxine ...
(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 homeostatic
In biology, homeostasis (British also homoeostasis) (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physical, and chemical conditions maintained by living systems. This is the condition of optimal functioning for the organism and ...
control of the HPT axis (hypothalamic–pituitary–thyroid axis
The hypothalamic–pituitary–thyroid axis (HPT axis for short, a.k.a. thyroid homeostasis or thyrotropic feedback control) is part of the neuroendocrine system responsible for the regulation of metabolism and also responds to stress.
As its na ...
). According to a 1993 article, such nodules need to be treated only if they become toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...
; surgical excision (thyroidectomy
A thyroidectomy is an operation that involves the surgical removal of all or part of the thyroid gland. In general surgery, endocrine or head and neck surgeons often perform a thyroidectomy when a patient has thyroid cancer or some other conditio ...
), radioiodine therapy
Iodine-131 (131I, I-131) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days. It is associated with nuc ...
, or both may be used.
See also
* Thyroid adenoma
A thyroid adenoma is a benign tumor of the thyroid gland, that may be inactive or active (functioning autonomously) as a toxic adenoma.
Signs and symptoms
A thyroid adenoma may be clinically silent ("cold" adenoma), or it may be a functional tumo ...
References
External links
{{DEFAULTSORT:Thyroid Nodule
Thyroid disease