Introduction
Cold nodules are inactive areas of nodular shape in the thyroid gland. They no longer produce hormones and indicate a more or less pathological change in the tissue. The causes of a cold node in the thyroid gland can be many and varied.
Both benign phenomena such as cysts, scars or adenomas (benign tumor) and malignant diseases such as malignancies (malignant tumor) must be clarified. A cold node can be associated with an underfunction of the thyroid gland. This means that the thyroid gland does not produce adequate amounts of hormones, which has various effects on the entire organism. In any case, if such a conspicuous finding is detected, a detailed examination is required.
Causes
A cold knot does not necessarily have to have a bad cause. There are several benign phenomena that appear as inactive areas in the scintigraphic image. Benign means that they are usually not devastating symptoms, but they must still be examined and usually treated.
However, the prognosis is usually better in contrast to confirmed diseases. Cysts belong to the group of benign causes of cold nodes in the thyroid gland. Cysts are chambers that can form in a wide variety of tissues.
They are lined with cover cells (epithelial cells) and contain a thin or thick inflammatory secretion. Due to the encapsulation to the surrounding tissue, an inflammation does not spread quickly, but the size of the cyst can increase over time. This may require surgery to remove the cyst.
At the site where the cyst is located, normal thyroid cells are no longer present. As a result, no radioactive contrast agent can be deposited there during a scintigraphy, resulting in a cold lump in the image. Furthermore, scars (also fibrosis) can appear as inactive thyroid areas.
Scars or fibrosis can occur in the course of inflammations that have healed on their own, but also as a result of surgery. In the case of scarring (fibrosis), the substance fibrin accumulates in the tissue, which represents a part of the coagulation system and hardens the corresponding area. If a part of the thyroid gland is removed, for example when a cyst or a tumor has to be treated, the tissue usually scars in the areas where incisions have been made.
Scarred tissue is harder than other tissue and loses its functions during this remodelling. Cold nodules caused by scars are therefore completely harmless as long as the function of the thyroid gland is not too severely restricted. If the fibrous areas gain the upper hand, as can happen after a very serious inflammation, there is a possibility of an underactive thyroid gland.
If traumatic events, such as an accident, cause damage to the neck region or the thyroid gland, this can lead to bleeding in the same. Pathological vascular changes that cause acute damage to the blood vessels can also be responsible for bleeding. Bleeding can damage the surrounding tissue and cause inactive areas in the thyroid gland.
These areas appear as before in the scintigraphic image as colorless cold nodes. Thyroid adenomas are benign tumors. They develop from the follicular epithelial cells of the thyroid gland (thyroidea), the so-called thyroid cells.
Follicular epithelial cells are cover cells that are arranged around tiny cavities in which, in the case of the thyroid gland, thyroid hormones are produced and stored. Mainly thyroid adenomas are associated with hyperthyroidism. If this is not the case and the proliferating cell groups are inactive cells, an adenoma can also be the cause of a cold node.
Unfortunately, however, most cold nodules associated with tumors are malignant and are referred to as thyroid cancer. Cold nodules are not uncommon in scintigraphic findings. Often benign diseases are the background of such striking images.
However, a malignant tumor disease should also be excluded at any time. Thyroid cancer characteristically presents itself as a cold nodule in the tissue if it is large enough. Since the laboratory findings are usually rather inconspicuous, the image or a questionable palpation can provide initial indications of a thyroid carcinoma.There are different types of thyroid cancer.
The forms are very different in their course as well as in the probable chances of cure. Papillary thyroid carcinomas have the best prognosis, accounting for about 65% of all malignant tumors. They are closely followed by the similar follicular thyroid cancer, which accounts for about 25% of all malignant tumors.
Rarer is the medullary thyroid carcinoma, which is formed from the C-cells of the thyroid gland. These cells produce the hormone calcitonin, which regulates the calcium balance. As a result of this fact, medullary tumor has a separate symptomatology, which is accompanied by an increased hormone level of calcitonin and a subsequent hypocalcaemia, a lack of calcium.
Very rare are anaplastic thyroid carcinomas, which at the same time have the lowest chances of cure. Due to the strong de-differentiation of the cells, the tumor grows extremely fast. De-differentiation means that the cells have nothing in common with the surrounding tissue – they do not resemble any cell found in the thyroid gland.
Therefore, the malignant tumor can be influenced, let alone stopped, by the least amount of therapeutic measures. Another possibility for cold nodules of malignant origin are metastases. However, the thyroid gland is extremely rarely affected by metastasis.
