Thyroid nodules are very common. The prevalence of thyroid nodules in the general population is 3% to 7% on palpation, while the prevalence of thyroid nodules on high-definition ultrasound is 20% to 70%. Most thyroid nodules are benign, and malignant nodules account for only about 5% of thyroid nodules. The key to the diagnosis and treatment of thyroid nodules is to identify benign and malignant. Among the various malignant tumors in the body, malignant tumors of the thyroid gland account for. Depending on the cause of the nodule, it can be divided into: nodular goiter, inflammatory nodule, toxic nodular goiter, thyroid cyst and thyroid tumor.
The vast majority of patients with thyroid nodules have no clinical symptoms and are often detected by physical examination or by their own touch or imaging. When the nodules compress the surrounding tissues, corresponding clinical manifestations such as hoarseness, breath-holding, and difficulty swallowing may occur. Since benign and malignant thyroid nodules do not have characteristic clinical manifestations, a variety of indicators need to be considered in the differential diagnosis.
Clinical evidence suggestive of a malignant thyroid nodule includes.
1. A history of treatment with neck radiography;
2. Family history of medullary thyroid carcinoma or multiple endocrine adenomatosis type 2 (MEN2);
3. Age less than 20 years or more than 70 years;
4, male;
5. Rapid growth of nodules with a diameter of more than 2 cm;
6, with persistent hoarseness, dysphonia, dysphagia and dysphagia;
7, nodules with hard texture, irregular shape and fixed;
8, with enlarged lymph nodes in the neck.
Ancillary tests are important in identifying benign and malignant thyroid nodules. High definition thyroid ultrasonography is the most sensitive method to evaluate thyroid nodules. It can be used not only to discriminate the nature of nodules, but also for ultrasound-guided fine needle aspiration and cytology (FNAC) of the thyroid gland.
Features suggestive of malignant lesions in nodules are.
Microcalcifications; irregular nodule margins; and disturbance of blood flow within the nodule. The specificity of the three features suggestive of malignant lesions is high, reaching more than 80%, but the sensitivity is low, ranging from 29% to 77.5%. Therefore, one feature alone is not sufficient to diagnose malignant lesions. However, if two or more features are present at the same time, or if one of these features is combined in a hypoechoic nodule, the sensitivity of diagnosing malignant lesions increases to 87% or 93%. Invasion of the hypoechoic nodule into the outer thyroid envelope or the muscles surrounding the thyroid gland or enlargement of the cervical lymph nodes with loss of intra-lymph node structures, cystic changes, or microcalcifications in the lymph nodes and disturbance of the blood flow signal suggest malignancy.
Fine needle aspiration and cytology (FNAC) of the thyroid gland is the most reliable and valuable diagnostic method for identifying benign and malignant nodules, with a sensitivity of 83%, specificity of 92%, and accuracy of 95%. Therefore, FNAC should be performed in all cases where malignant nodules are suspected.
Thyroid nuclide imaging is characterized by the ability to evaluate the function of the nodule. Nodules are classified as “warm nodules” or “cold nodules” according to their ability to take up radionuclides. In general, 99% of the “hot nodules” are benign and malignant nodules are extremely rare. The rate of malignancy in “cold nodules” is only 5%-8%. Nuclear tumor imaging is of great value in the differential diagnosis of benign and malignant thyroid nodules and in the whole-body imaging of patients with possible recurrence and metastasis of thyroid cancer after surgery.
Serum TSH and thyroid hormone levels should be measured in all patients with thyroid nodules. The majority of patients with thyroid malignancy have normal thyroid function; serum thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb) levels are among the gold indicators for detecting Hashimoto’s thyroiditis, especially if serum TSH levels are elevated. Measurement of thyroglobulin (Tg) levels is not helpful in identifying the nature of the nodule. Those with a family history of medullary thyroid cancer or multiple endocrine adenomatosis should have their serum calcitonin levels measured in the basal or stimulated state. A significantly elevated serum calcitonin level suggests a medullary thyroid nodule.
It is important to note that the benignity or malignancy of a nodule is not related to the size of the nodule; it is not related to whether the nodule is palpable; it is not related to whether the nodule is solitary or multiple; and it is not related to whether the nodule is combined with cystic changes.
For the management of malignant thyroid nodules, surgery is preferred. For benign lesions, the majority of patients do not require treatment and follow-up is the main tool.
A small number of benign lesions require treatment. The current treatments are as follows.
1, levothyroxine (L-T4) suppression therapy: The aim of treatment is to shrink existing nodules; however, studies have found that only 20% of thyroid nodules shrink in L-T4-treated patients compared to before, and it has also been found that shrunken thyroid nodules can become larger again after stopping the drug. Because long-term use can lead to significant reduction in bone mineral density, atrial fibrillation and other adverse effects, L-T4 therapy is not recommended for widespread use, especially not for male patients older than 60 years of age with serum 1 IU/L or postmenopausal women or those with combined cardiovascular disease.
2. Ultrasound-guided percutaneous alcohol injection therapy is a minimally invasive treatment for thyroid nodules, mainly used to treat thyroid cysts or nodules combined with cystic changes. Since this method has a high recurrence rate and lacks evidence-based medical evidence for long-term effects, it is not recommended for single, solid nodules.
3. Radioactive I-131 therapy is used for those with autonomic high-functioning adenoma, toxic nodular goiter with thyroid volume less than 100 ml or those who are not suitable for surgical treatment or recurrence of surgical treatment. The purpose of radioactive I-131 treatment is to remove functional autonomic nodules and restore normal thyroid function, with an effectiveness of 80% to 90%.
4. Treatment of suspected malignant and undiagnosed thyroid nodules: If the diagnosis of cystic or solid thyroid nodules is not clear by FNAC examination, FNAC examination should be repeated so that the diagnosis is clear in 30% to 50% of the patients. If the diagnosis is still not confirmed by repeated FNAC examinations, especially if the nodule is large and shows local pressure symptoms, surgery is required.
The management of thyroid nodules found during pregnancy follows the same strategy as that of thyroid nodules found during non-pregnancy. However, thyroid nuclide imaging and radioactive iodine therapy are prohibited during pregnancy. Thyroid nodules in children are relatively rare, but the rate of malignancy is significantly higher than in adults. Therefore, FNAC should also be performed in children with thyroid nodules, and other management options are similar to those for adults.