Most patients with thyroid cancer are initially diagnosed with a “thyroid nodule”, but most thyroid nodules are not cancer. Therefore, there is no need to worry too much when you are diagnosed with a thyroid nodule, just follow your doctor’s recommendations for further tests. Today, let’s have a preliminary understanding of thyroid nodules.
A thyroid nodule is a lump in the thyroid gland that moves up and down with the thyroid gland in response to swallowing movements and is a common clinical condition that can be caused by a variety of etiologies. A variety of clinical thyroid disorders, such as thyroid degeneration, inflammation, autoimmunity, and neoplasia, can manifest as nodules. Thyroid nodules can be solitary or multiple. Multiple nodules have a higher incidence than solitary nodules, but solitary nodules have a higher incidence of thyroid cancer.
[Etiology of thyroid nodules].
Thyroid nodules can be caused by various etiologies.
1.Proliferative nodular goiter
High or low iodine intake, consumption of goiter-causing substances, consumption of goiter-causing drugs or defective thyroid hormone synthetase, etc.
2.Neoplastic nodules
Benign thyroid tumors, papillary thyroid tumors, follicular cell carcinoma, medullary thyroid carcinoma, undifferentiated carcinoma, lymphoma, and other malignant tumors of follicular and non-follicular cells of the thyroid gland, as well as metastatic carcinoma.
3.Cysts
Nodular goiter, degenerative adenoma and old hemorrhagic spot cyst, cystic thyroid cancer, congenital thyroglossal cyst and cyst caused by the remnants of the fourth gill slit.
4.Inflammatory nodules
Acute septic thyroiditis, subacute septic thyroiditis, and chronic lymphocytic thyroiditis can all appear in the form of nodules. In rare cases, thyroid nodules are caused by tuberculosis or syphilis.
Clinical manifestations
1. Nodular goiter
It is common in middle-aged women. In the absence of thyroid hormone in the body, the pituitary gland secretes more TSH. Under the long-term stimulation of this increased TSH, the thyroid gland undergoes repeated or continuous hyperplasia resulting in uneven enlargement and nodule-like changes in the thyroid gland. There may be bleeding, cystic changes and calcifications within the nodules. The size of the nodules can range from a few millimeters to several centimeters. The main clinical manifestation is an enlarged thyroid gland with multiple nodules of varying sizes on palpation. Patients have few clinical symptoms, usually only anterior neck discomfort, and thyroid function tests are mostly normal.
2. Nodular toxic goiter
This disease starts slowly and often occurs in patients who have had nodular goiter for many years, mostly at the age of 40 to 50 years or older, and is more common in women. When the thyroid gland is palpated, a smooth round or oval nodule with clear borders and a hard texture can be found, which moves up and down with swallowing. Thyroid function tests may show elevated thyroid hormones in the blood, and if the nodule is functionally autonomous, a nuclear scan may show a “hot nodule”.
3. Inflammatory nodules
Infectious and non-infectious nodules, the former is mainly caused by viral infection of subacute thyroiditis, other infections are rare. The latter is mainly caused by autoimmune thyroiditis, mostly seen in middle-aged and young women, the patient’s conscious symptoms are less, the examination can be found in multiple or single nodules, hard and tough texture, less pressure pain, thyroid function tests show thyroglobulin antibodies and The thyroid function tests often show strong positivity for thyroglobulin and thyroid microsomal antibodies.
4. Thyroid cysts
Most of them are formed by degenerative changes of goiter nodules or adenomas, containing blood or slightly mixed liquid, with clear borders and hard texture, usually without pressure pain. In a few patients, it is caused by congenital thyroglossal cysts or remnants of the fourth gill slit.
5.Thyroid tumor
It includes benign thyroid tumor, thyroid cancer and metastatic cancer.
Examination means
1.Serological examination
Abnormal thyroid function cannot exclude thyroid cancer but indicates that it is less likely. Having hyperthyroidism or lower TSH indicates autonomous functional thyroid adenoma, nodule or toxic multinodular goiter. Patients with medullary thyroid carcinoma have elevated serum calcitonin levels, but require stimulation with pentagastrin and calcium in the early stages of C-cell proliferation.
2.Nuclear scan
Scans are less significant in distinguishing benign and malignant lesions. Most benign and malignant substantial nodules are hypofunctional relative to the surrounding normal glandular tissue; therefore, detection of cold nodules is rarely specific, and overlapping uptake of nuclide from surrounding normal glandular tissue can miss small nodules. Many thyroid cancers can uptake Tc, therefore, there are still some cancer cases in hot nodules.
3.Ultrasound diagnosis
Ultrasound is reliable for the diagnosis of cystic lesions. It has very little value in distinguishing benign from malignant. However, it is meaningful in discriminating nodule size, identifying nodule site, and guiding localization puncture.
4.Other nuclide examination
Positron emission tomography can be used to examine nodular thyroid lesions and identify benign and malignant tumors, and proton magnetic resonance seems to identify normal glandular tissue and cancerous tissue.
5.Fine needle aspiration cytology
It is helpful in the management of nodules. The widespread use of this method has greatly reduced unnecessary thyroid surgery, improved the detection rate of intraoperative malignancies, and reduced the cost of managing thyroid nodules. The accuracy of fine needle aspiration cytology is 70% to 90%, which is related to the experience of aspiration and cytological diagnosis.
6. Fine needle aspiration cytology of the thyroid
FNAC results have a 90% compliance rate with surgical pathology results. There is only a 5% false-negative rate and a 5% false-positive rate. Of course the compliance rate depends on the success rate of the operator and varies widely.
7.X-ray of the neck
Those with fine or sand-like calcifications on the nodules may be sand bodies of papillary carcinoma. Large and irregular calcifications can be seen in degenerative nodular goiter or thyroid cancer. If infiltration or deformation is seen in the tracheal image, it suggests a malignant lesion.
8.Thyroid function measurement
Functionally autonomous toxic nodules are most often hyperthyroid, and early stages of subacute thyroiditis can also be hyperfunctional. Thyroid function in chronic lymphocytic thyroiditis can be normal, hyperactive, or hypothyroid.