Generality
The thyroid nodules are anomalous protuberances of the thyroid gland, having a more often benign than malignant nature.
Of extremely variable dimensions, the thyroid nodules can present themselves in different ways: they can be single or multiple protuberances; they can reside on the surface of the thyroid or in the deeper layers of the latter; may be symptomatic or asymptomatic; they can stimulate or depress the hormonal activity of the thyroid; etc.
The identification of thyroid nodules and the precise identification of their nature requires: physical examination, medical history, blood test, thyroid ultrasound, thyroid scintigraphy and, sometimes, thyroid needle biopsy.
The treatment of thyroid nodules depends on their nature.
Brief review of the anatomy and functions of the thyroid
The thyroid gland is an unequal organ, located in the anterior region of the neck, at the base of the throat.
Similar in shape to a butterfly, the thyroid plays a very important physiological role, as it deals with regulating:
- Body metabolism (for example, affects oxygen consumption; controls the synthesis and degradation of cholesterol; stimulates lipolysis and lipogenesis; increases glycogenolysis and gluconeogenesis, etc.);
- Skeletal and cerebral development, starting from fetal life;
- Protein synthesis;
- The development of the skin, the hair apparatus and the genital organs;
- The heartbeat;
- Body temperature;
- The hematopoiesis.
Its weight is generally equivalent to about 20 grams, but it can undergo variations throughout life (for example during puberty, menopause, pregnancy, menstruation, breastfeeding, etc.).
In women, it is smaller than in men.
To carry out all these regulatory activities, the thyroid uses three hormones that it produces by itself and injects into the blood. The hormones in question are: triiodothyronine (also called T3 ), thyroxine (also called T4 ) and calcitonin .
The own production of hormones and their introduction into the blood circulatory stream cause the thyroid to re-enter the list of human endocrine glands.
What are thyroid nodules?
Thyroid nodules, or thyroid nodules, are well circumscribed and delimited abnormal enlargements of portions of the thyroid.
Extremely variable in size, thyroid nodules almost always have a benign nature and, only in rare cases, hide a malign neoplasm .
Other characteristics
Thyroid nodules can present themselves in many different ways: they can be masses filled with liquid or filled with liquid and solid material; they can be solid masses; they can enjoy a certain mobility or be completely fixed; they can occupy any portion of the thyroid; they can reside on the surface or in the deeper layers of the thyroid gland; they can appear individually (a single nodule) or multiple (two or more nodules).
Benigni or Maligni?
Although rare, the possibility that the thyroid nodules have a malignant nature scares most of the patients that present abnormal masses circumscribed at the level of the thyroid.
With this article, we want not only to talk about thyroid nodules in general, but also how probable their malign evolution is and how we can notice it.
Thyroid nodules: which pathological category do they belong to?
Thyroid nodules are included in the list of so-called thyroid diseases, along with hyperthyroidism, hypothyroidism, goiter, thyroid cancer and thyroiditis .
Based on reliable statistical surveys, thyroid diseases mainly affect women and older people .
Moreover, from other researches, a particular association emerged with type 1 diabetes mellitus, pernicious anemia, rheumatoid arthritis, autoimmune diseases, iodine deficiency in the diet and massive exposure to ionizing radiation.
Epidemiology
Thyroid nodules are very common in the general population. The women, the elderly and those living in the so-called geographical areas lacking in iodine suffer most.
Detection of thyroid nodules in children and adolescents is quite rare.
From different statistical studies it emerged that:
- In the adult population, the prevalence of only palpable thyroid nodules is 3-7%, while the prevalence of palpable and non-palpable thyroid nodules (due to the small size) fluctuates between 30% and 60%;
- The frequency of thyroid nodules in the female population is about four times higher than the frequency of thyroid nodules in the male population;
- Only 5-10% of all thyroid nodules are malignant.
Causes
Currently, it is not clear what the precise pathophysiological mechanism that leads to the formation of thyroid nodules; however, in the course of their extensive research, doctors have noted an association between these particular thyroid enlargements and some specific conditions, as if there was a consequential link between the two circumstances.
The conditions in question are:
- Dietary iodine deficiency . Iodine is a mineral essential for the proper functioning of the thyroid. In fact, if the iodine is missing, the thyroid gland is not able to properly synthesize its hormones.
The lack of iodine in the diet is a problem that, nowadays, is more common in the poorer geographical areas of the planet and in those where there are few natural sources of iodine;
- Thyroid adenoma . It is a benign tumor that develops from a cell of the thyroid secretory tissue.
In most cases, it is harmless and symptom-free; more rarely, it is responsible for a hyperactivity or hypoactivity of the thyroid, with consequent development, in the first circumstance, of hyperthyroidism and, in the second circumstance, of hypothyroidism;
- The presence of a thyroid cyst . Thyroid cysts are small protuberances located on the thyroid gland, filled with liquid, solid-liquid or just solid material.
Generally, they derive from the degeneration of thyroid adenomas, of which they retain the benign nature; more rarely, they are the result of malignant neoplastic transformations.
- Thyroiditis . It is inflammation of the thyroid. The best known example of thyroiditis is the so-called Hashimoto's thyroiditis.
- Multinodular goiter . In medicine, the term "goiter" indicates the generalized enlargement of the thyroid.
Multinodular goiter is the generalized enlargement of the thyroid due to the presence of numerous thyroid nodules.
- Thyroid cancer . It is the malignant tumor of the thyroid gland.
Types of thyroid nodules | |
| Type | Features |
| Single nodules (or solitary nodules) | They are the thyroid nodules that occur in single mode. Malignant thyroid nodules are generally single. |
| Multiple nodules | They are the thyroid nodules that occur in multiple mode. |
| Autonomous nodules | They are the thyroid nodules that alter the hormonal activity of the thyroid. If they over-activate the thyroid, they are called hyperfunctioning autonomous nodules ; if instead they depress the thyroid, they are called autonomous hypofunctional nodules . |
| Cancerous nodules | They are the thyroid nodules that make up malignant thyroid tumors. |
| Cystic nodules | They are the thyroid nodules that characterize the condition known as thyroid cysts. |
| Adenomatous nodules | They are the thyroid nodules that distinguish thyroid adenomas. |
| Non-cancerous colloidal nodules | They are the thyroid nodules that form at the level of the thyroid follicles. |
When it is more probable the presence of malignant thyroid nodules
According to experts, the presence of malignant thyroid nodules is more frequent in:
- Patients with a family history of thyroid cancer ;
- Patients who have a previous history of radiation therapy or exposure to high doses of environmental ionizing radiation ;
- Smoking patients;
- Patients with goiter associated with unexplained hoarseness or stridor ;
- Male patients;
- Patients with Hashimoto's thyroiditis .
Symptoms and complications
To learn more: Symptoms Nodules of the thyroid
The possible presence of a symptomatology connected to the thyroid nodules may depend on:
- The uncomfortable position, the large size and / or the multiple appearance mode of the thyroid nodules
Or
- The influence that some thyroid nodules may have on thyroid hormonal activity .
In the first circumstance (thyroid nodules in an uncomfortable position, large in size, etc.), the affected person can manifest:
- Discomfort and, at times, real pain, where the thyroid nodules reside;
- Large thyroid, evidenced by a swelling on the neck;
- Difficulty in swallowing due to compression exerted by the thyroid nodules on the esophagus;
- Hoarseness;
- Breathing problems due to compression exerted by thyroid nodules.
In the second circumstance (thyroid nodules that influence the hormonal activity of the thyroid), instead, the patient can develop
- the typical symptoms of hyperthyroidism, if the thyroid nodules stimulate the hormonal activity of the thyroid (most common case);
- the typical disorders of hypothyroidism, if the thyroid nodules block the activity of the thyroid (less common case).
For readers who need a review, the characteristic symptoms of hyperthyroidism are: hyperhidrosis (or excessive sweating), increased body temperature, increased heart rate, tremors, heat intolerance, fatigue, weight loss, increased appetite, tachycardia and nervousness; while, the classic symptoms of hypothyroidism are: dry skin, thinning hair, mixed- facial facies, tiredness, cold skin, bradycardia, drowsiness, constipation and low-temperature intolerance.
Peculiar characteristics of malignant thyroid nodules:
- Rapid growth. Malignant thyroid nodules rapidly enlarge and within a few weeks;
- Presence of laterocervical palpable lymphadenopathy (in simpler words, enlarged lymph nodes in the neck);
- Single appearance mode. The simultaneous presence of multiple thyroid nodules is rarely a sign of malignancy;
- Hard consistency on palpation and poor mobility;
- If they influence the hormonal activity of the thyroid, they tend more often to have a depressing rather than stimulating effect.
Is there a way to notice the presence of thyroid nodules?
If superficial, or large and not particularly deep, the thyroid nodules can be identified by palpation of the thyroid, even by an inexperienced hand.
When should I go to the doctor?
Despite the generally benign nature of the thyroid nodules, the response to palpation of an enlargement or more swelling, at the level of the thyroid, always and in any case requires contacting your treating physician immediately, to undergo all the necessary medical checks.
Complications
Possible complications associated with the presence of thyroid nodules are:
- A drastic worsening of the pain sensation, respiratory problems and swallowing disorders;
- The occurrence of the typical consequences of untreated hyperthyroidism or untreated hypothyroidism;
- The malignant evolution of a previously benign thyroid nodule.
Diagnosis
In general, the procedure of diagnostic tests for the identification and study of the characteristics of thyroid nodules begins with an accurate physical examination of the thyroid and a scrupulous anamnesis of the patient; after which, he continues with a thyroid ultrasound and blood tests ; finally, it ends with a thyroid scintigraphy and a needle biopsy of the thyroid .
Physical examination and medical history
The physical examination is the set of diagnostic maneuvers, performed by the doctor to verify the presence or absence, in the patient, of signs indicative of an abnormal condition.
- In the case of thyroid nodules, the objective examination consists substantially in the palpatory analysis of the thyroid, aimed at identifying any suspicious protuberances.
The anamnesis, instead, is the collection and the critical study of the symptoms and the facts of medical interest, denounced by the patient or by his relatives (NB: the contribution of the relatives is fundamental above all when the patient is of a young age).
- In the case of thyroid nodules, the anamnesis focuses mainly on the search for conditions favoring / associated with the presence of thyroid enlargements (eg iodine deficiency, risk factors for malignant thyroid nodules, etc.).
Ultrasound of the thyroid
Painless and non-invasive examination (NB: it uses ultrasounds), the ultrasound of the thyroid not only allows to confirm the presence of thyroid nodules, but also to establish the exact position, the precise dimensions, the consistency of the content (solid or liquid) etc.
Blood analysis
The blood tests are useful for the doctor to have a data concerning the blood levels of thyroid hormones T3 and T4 and of the pituitary hormone TSH, which controls the secretion of thyroid hormones.
Thanks to blood tests, it is possible to determine whether, in patients with thyroid nodules, a condition of hyperthyroidism or hypothyroidism is underway.
Who to contact, if thyroid nodules alter thyroid function?
The medical figure to which it is essential to turn, in the case in which the thyroid nodules alter the hormonal activity of the thyroid, is that of the endocrinologist, that is a doctor specialized in endocrinology .
Thyroid scintigraphy
Thyroid scintigraphy is a diagnostic examination of nuclear medicine, which allows the thyroid to be studied in detail, from its functioning to its anomalies.
If practiced to analyze nodules, thyroid scintigraphy clarifies not only the shape, size and location of enlargements, but also the influence that such enlargements have on the hormonal activity of the thyroid.
- Thyroid nodules which, according to thyroid scintigraphy, have a stimulating effect against the hormonal activity of the thyroid are called " hot nodules "; on the contrary, the thyroid nodules which, according to thyroid scintigraphy, depress the hormonal activity of the thyroid and are called " cold nodules ".
- The "cold nodules" (ie those also called hypofunctioning nodules) have a greater tendency to have a malignant nature, compared to "hot nodules" (ie those also known as hyper-functioning nodules).
Needle biopsy of the thyroid
The needle biopsy of the thyroid is a moderately invasive bioptic examination, which consists in taking a sample of thyroid cells, using a special needle, and in their subsequent analysis in the laboratory.
Performed on the thyroid nodules, the thyroid needle biopsy allows us to establish with extreme precision the benign or malignant nature of anomalous enlargements.
Among the diagnostic tests used to identify a malignant thyroid nodule, it is undoubtedly the most useful and indicated.
The correct and extended name of the needle biopsy on thyroid nodules is thyroid needle aspiration with cytological examination .
How are asymptomatic thyroid nodules diagnosed?
Often, the identification of asymptomatic thyroid nodules is completely random and occurs through palpation of the neck or medical examinations, performed for other reasons.
How do doctors recognize a malignant nodule?
Doctors have various tools available to suspect and eventually ascertain the malignancy of a thyroid nodule.
First of all, the levels of TSH are evaluated, ie the pituitary hormone that stimulates the thyroid to secrete hormones T3 and T4:
- A TSH value in the standard is an index of thyroid endocrine balance, so the clinical investigation can stop.
- In the case of altered TSH, the levels of free thyroxine are measured, possibly associated with the anti-tyyoglobulin and anti-thyroperoxidase antibodies (AbTg and AbTPO).
- In the case of low TSH and high levels of FT4 (free T4), the nodule is probably over-functioning, so the character of malignancy is very unlikely.
- In the case of normal or high TSH, further instrumental diagnostic tests are generally necessary.
The first level instrumental investigation consists of the ultrasound of the thyroid, which allows to evaluate the number, location, dimensions and characteristics of the nodules; the risk of malignancy, in this case, increases in the presence of an isolated and hypoechoic nodule (ie ultrasonographically solid), in the presence of intranodular microcalcifications and, finally, in the presence of blurred or irregular margins.
Other first line instrumental investigations are the aforementioned thyroid scintigraphy and eco-color-doppler: the first evaluates - as we have seen - the endocrine activity, while the second evaluates the degree of vascularization of the nodule or nodules. A malignant nodule is more likely to present itself as a "cold" (or hypo-secreting), peri- and intra-nodular hypervascular nodule.
The correct interpretation of the risk factors and of the ultrasound and scintigraphic criteria listed above can only provide an indication of the benign or malignant nature of a thyroid nodule.
The most effective method of investigation for the differential diagnosis between malignant and benign thyroid nodules is thyroid aspiration (FNAb) with cytological examination.
Dr. Giampaolo Papi, in his infotiroide.it website, publishes an interesting flow-chart on the diagnostic-therapeutic approach to the patient with thyroid nodule, hereinafter resumed purely for information:
Therapy
To learn more: Drugs for the treatment of thyroid nodules
Therapy and treatment of thyroid nodules depend on their nature and their peculiarities:
- In the case of benign thyroid nodules, associated with hyperthyroidism (hyperfunctioning nodules), the therapeutic program includes:
- Radioactive iodine therapy 131;
- Surgical removal of a more or less extensive area of the thyroid gland ( partial thyroidectomy );
- Drugs for the treatment of hyperthyroidism (eg: methimazole).
- In the case of benign thyroid nodules that do not affect thyroid activity ("normal-functioning nodules"), the doctor may opt for:
- Constant monitoring of the size and characteristics of the nodule, and of the blood indices related to the hormonal activity (endocrine function) of the thyroid;
- Prescription of a "TSH-suppressive" drug therapy with levothyroxine, in order to keep TSH levels to a minimum; the theoretical assumption of this treatment, whose clinical benefit is still the subject of discussion, is the reduction of the stimulating effect of TSH towards the growth of thyroid nodules;
- Surgical removal of a more or less extensive area of the gland (partial thyroidectomy), if the thyroid nodules cause difficulty in swallowing and / or breathing.
- In the case of malignant thyroid nodules, the possible therapeutic choices are:
- Surgical removal of the thyroid (total thyroidectomy), possibly associated with excision of local lymph nodes;
- Alcoholic ablation. In short, this treatment involves the elimination of the malignant nodule, through the injection, in correspondence of the same nodule, with a small quantity of alcohol;
- Drugs specifically indicated for the treatment of thyroid cancer. It represents the only viable solution, when the malignant nodule is a diffuse (metastatic) carcinoma, inoperable and not even treatable with radioactive iodine.
What are the effects of removing the total?
The most immediate side effect of total or partial thyroid removal (the aforementioned thyroidectomy) is hypothyroidism, which, however, can now be treated easily by means of hormone replacement therapy based on L-thyroxine .
Prognosis
Being in most cases benign and asymptomatic, thyroid nodules tend to have a favorable prognosis.
The reasons why the prognosis of thyroid nodules could become unfavorable or otherwise become uncertain are:
- The presence of symptoms that make it necessary to have a part or all of the thyroid removed (with all the consequences);
- The malignant nature of the abnormal mass present on the thyroid. In such situations, in order to hope for healing, early diagnosis is essential.
Prevention
Currently, there is no preventive measure against thyroid nodules.
