The presence of a thyroid nodule is a very common condition. By itself, a lump does not represent a disease itself, but it is a sign of a thyroid gland problem. From a certain point of view, nodules are the common expression of numerous thyroid diseases. In fact, many of the diseases that affect the thyroid - such as hypothyroidism and hyperthyroidism, but also benign and malignant tumors - are united by the presence of one or more nodules. The goiter itself can also assume uninodular or multinodular characteristics.
But let's go into more detail and see what thyroid nodules are.
Thyroid nodules are spherical protuberances or growths, which develop locally within the thyroid. These lumps can be solid, liquid, or mixed, i.e. formed by a solid and a liquid component.
Thyroid nodules can be extremely small, and even measure less than a millimeter, or reach a width of a few centimeters.
Finally, thyroid nodules can be single or multiple, and occur in a normal or enlarged gland.
Obviously, the presence of the nodules more or less conspicuously alters the normal uniform appearance of the thyroid.
Thyroid nodules are mostly benign, meaning they do not affect thyroid function and cause no symptoms. For this reason, very often their discovery occurs in a completely random way, during medical examinations performed for different reasons.
In a minority of cases, some nodules can autonomously produce excess thyroid hormones, thus causing hyperthyroidism, while only a very small percentage hides a neoplastic, and therefore tumor, nature.
For this reason it is always useful to carefully evaluate all nodules; in this way, the doctor can rule out the presence of possible dysfunctions and ascertain that it is not a malignant tumor, which is clearly more dangerous.
There are several causes responsible for the onset of thyroid nodules.
As we have seen, a lump is an overgrowth of thyroid tissue, often of a benign non-neoplastic nature. Among the possible causes of benign nodules, we mention cysts, some inflammatory processes such as Hashimoto's thyroiditis, and enlargement of the thyroid gland (or goiter).
A nodule can also develop due to the action of growth factors external to the thyroid, such as the stimulation of TSH secreted by the pituitary, or of factors internal to the thyroid, such as defects in one or more stages of the synthesis of thyroid hormones, including the iodine deficiency.
The tumor nodule, on the other hand, arises from the clonal development of a mutated cell, which gives rise to a carcinoma or an adenoma.
Most thyroid nodules do not manifest themselves with actual symptoms. On some occasions, at most, they can cause a modest local disturbance. Their presence is noticeable only when they are identifiable on palpation. In other words, if their size does not reach considerable values, the nodules are not easily perceptible on palpation and the help of specific instrumental investigations such as thyroid ultrasound is required.
When the size of the nodules is considerable, specific symptoms can appear, due to the pressure exerted by the nodules against the neck. Among these symptoms we remember the sense of constriction, the alteration of the voice and difficulties in swallowing and breathing.
When, on the other hand, the lump is hyperactive, that is, it produces excess thyroid hormones, it can accompany the signs of hyperthyroidism, such as tachycardia, weight loss, nervousness and diarrhea.
In opposite cases, the nodules can arise in a context of hypo-function of the thyroid gland: in this case we speak of hypothyroidism, with symptoms such as bradycardia, weight gain, constipation and fatigue.
Turning to the diagnosis of thyroid nodules, the initial evaluation of the patient must include the clinical history, a medical examination and some blood and instrumental tests.
Blood tests, in particular, must measure thyroid function, then determine the levels of thyroid hormones and TSH. The measurement of anti-thyroid antibodies in the blood, on the other hand, allows us to check whether an autoimmune thyroid disease (such as, for example, Hashimoto's thyroiditis) is present. The blood dosage of calcitonin, on the other hand, serves to exclude a rare type of thyroid carcinoma, called medulla, which derives from parafollicular cells and causes an abnormal increase in the hormone calcitonin in the blood.
The instrumental tests allow to distinguish the various types of nodules. The most important examination in the study of nodular pathology of the thyroid is ultrasound, preferably with color doppler. This examination allows to obtain an image of the thyroid, through the use of ultrasound, and accurately evaluates the size of the nodules, their structure (which as we have seen can be solid or liquid or mixed), the presence of micro calcifications, the characteristics of the nodular margins and their degree of vascularization.
It should be noted that liquid and cystic nodules appear as cavities filled with fluid and are predominantly benign; instead, it is among the solid or mixed nodules that we find most of the malignant nodules.Ultrasound is also a very useful exam for subsequent checks, planned to monitor the evolution of the disease.
Another useful investigation is thyroid scintigraphy, which allows to define the characteristics of the nodule based on its endocrine activity. More specifically, if the cells are hyperactive, that is, they produce more thyroid hormones than the neighboring areas, they are able to accumulate a greater amount of radioactive iodine, which becomes evident during the scan. In this case, it is called a warm nodule. The hyperfunctioning area is highlighted on the scan for greater contrast than the surrounding thyroid regions. Conversely, if the group of cells have a less contrast, it means that they are underactive and the nodule is cold or hypofunctional.
The most useful test for diagnosing thyroid cancer is instead the needle aspiration. This test allows to clarify the nature of the nodule, even in patients with normal thyroid function. The needle aspiration is performed by inserting, under ultrasound control, a fine needle into the nodule in order to be able to aspirate some cells to submit them to cytological examination (then the cells are observed under the microscope by the anatomopathologist).
The correct treatment of a thyroid nodule is basically defined according to the cause of origin. If the thyroid nodule is benign, normal-functioning, and free of cancer cells, it can simply be monitored to make sure it doesn't grow any further.
In some cases, the doctor may indicate thyroid hormone suppressive drug treatment or metabolic radiotherapy to stop the growth of the lump.
If the lump rapidly increases in size or if there are compression or aesthetic problems, it may be necessary to partially or completely remove the thyroid.
Finally, in cases where the cytological examination confirms the malignant nature of the nodule, the treatment involves surgery, which is a valid tool for eliminating the cancerous nodule, especially if supported by TSH-suppressive or radiometabolic therapy. The patient will need to be followed with great care, but with proper treatment, complete recovery is possible in most cases.
