I. What is a thyroid nodule?
A thyroid nodule is an isolated lesion in the thyroid gland that is palpable and can be detected on ultrasound as distinct from the surrounding tissue. A nodule that is palpable but not confirmed on ultrasound is not diagnosed as a thyroid nodule. Thyroid nodules are not a single thyroid disease, but can be manifested in a variety of thyroid diseases, including degeneration, inflammation, autoimmune diseases, tumors and other lesions of the thyroid gland, collectively known as thyroid nodules. Zheng Zhaomin, Department of Minimally Invasive Oncology, Shandong Qianfo Mountain Hospital
What is the incidence of thyroid nodules?
Epidemiological surveys show that 5% of women and 1% of men living in non-iodine deficient areas have palpable thyroid nodules. With high-resolution ultrasound, the detection rate of thyroid nodules in the population can be as high as 19% to 67%, of which 5% to 10% are thyroid cancer. In iodine-deficient areas, the incidence of thyroid nodules is higher.
What are the classification and causes of thyroid nodules?
Thyroid nodules are classified into two categories: benign and malignant, most of which are benign.
The common diseases that cause benign thyroid nodules are as follows.
(a) Simple goiter.
(b) Thyroiditis: including 1. subacute thyroiditis 2. chronic lymphocytic thyroiditis 3. aggressive fibrous thyroiditis.
(C) thyroid adenoma.
The common disease causing malignant thyroid nodules is thyroid cancer, including papillary, follicular, medullary and undifferentiated carcinoma of the thyroid. The majority of these are papillary carcinomas, accounting for 90% of cases. Other rare malignant nodules of the thyroid include metastatic carcinoma and lymphoma.
The vast majority of benign thyroid nodules are not harmful. Larger thyroid nodules can compress the surrounding trachea, esophagus and laryngeal nerve, causing breathing problems, swallowing difficulties or hoarseness.
Fourth, if a thyroid nodule is found, the first thing to determine is whether it is benign or malignant
Diagnostic methods include comprehensive history taking and physical examination and laboratory, imaging and cytological examinations.
Laboratory tests include measurement of serum thyrotropin (TSH), serum thyroglobulin (Tg), and serum calcitonin; a low TSH indicates that the nodule may be secreting thyroid hormones, which are mostly benign and rarely malignant. Elevated TSH suggests the possibility of Hashimoto’s thyroiditis with hypothyroidism. Serum thyroglobulin (Tg) is only used to monitor recurrence or metastasis of thyroid cancer after surgery or isotope therapy. A serum calcitonin measurement of >100 pg/ml may indicate the presence of medullary thyroid carcinoma.
High-resolution color ultrasonography of the thyroid is the preferred and routine screening imaging for evaluation and follow-up of thyroid nodules. Papillary thyroid carcinoma usually presents as a hypoechoic parenchymal or predominantly parenchymal cystic nodule accompanied by irregular margins and increased blood flow within the nodule. Minute calcifications (less than or equal to 2 mm) are highly suggestive of papillary thyroid carcinoma, but are sometimes difficult to distinguish from gliosis. Dotted strong echogenicity within a thyroid nodule with a posterior comet tail is often a dense colloid. When this sign is present there is a greater than 85% probability that it is benign. Follicular carcinomas are more likely to appear hyperechoic or isoechoic with a thick irregular halo. Follicular carcinomas smaller than 2 cm are usually not associated with metastases. Some ultrasound features are highly suggestive of benignity. Purely cystic lesions are rarely malignant. Spongiotic lesions (multiple tiny cystic lesions occupying more than 50% of the nodule volume) are 99.7% benign.
Fine needle aspiration biopsy (FNA) of the thyroid gland is the most accurate method to distinguish benign and malignant thyroid nodules other than surgery, with an accuracy rate of 90%, but with a false negative rate of 5% and a false positive rate of 1%.
V. How to treat malignant thyroid nodules and benign thyroid nodules?
Malignant thyroid nodules (thyroid cancer) are usually treated with surgery.
Most benign thyroid nodules do not require treatment, but only follow-up observation. A few require microwave or radiofrequency ablation therapy or surgery.
Surgical treatment of benign thyroid nodules removes part of the thyroid gland along with the nodule, requires postoperative medication to replace thyroid function, and leaves a scar on the neck.
Thermal treatment of tumors is called thermal ablation therapy, and more and more information shows that microwave and radiofrequency ablation can achieve better results in the treatment of benign thyroid nodules. The rate of recurrent nodules after surgery for benign thyroid nodules is very high, so surgery is not the primary treatment for patients with this type of disease.
Currently, the following types of thyroid tumors have been conclusively proven to be suitable for microwave and radiofrequency ablation treatment.
(i) Benign nodules: thyroid adenomas, nodular goiter, colloid thyroid retention (also called cysts), and mass-like Hashimoto’s thyroiditis.
(b) Malignant nodules: thyroid cancer, recurrent thyroid cancer, metastatic or recurrent cancer of the lymph nodes in the neck, thyroid lymphoma.
(c) Nodules affecting aesthetics, and patients who request surgical treatment themselves.
(D) Those who have symptoms of tracheoesophageal compression.
(5) Those with hyperthyroidism.
Thermal ablation of thyroid tumors is a reliable and preferred option from the perspectives of minimally invasive, cosmetic, safety and effectiveness.