Thyroid nodules are common lesions in the head and neck area and are simply defined as lesions in the thyroid gland that are visible on imaging as separate from the surrounding thyroid parenchyma. A single nodule is not a formal diagnosis and usually requires a series of tests to try to clarify it. In addition, nodules that can be palpated by hand are not necessarily real, such as inflammation. Conversely, some nodules are more insidious and cannot be palpated. Epidemiological data suggest that palpable nodules can be detected by physical examination in 5% of women and 1% of men, while ultrasound random screening can detect the presence of thyroid nodules in 19-67% of patients, and only 5-15% of all these nodules are ultimately confirmed as malignant.
The main categories of cases requiring surgery include the following.
1) differentiated thyroid cancer, which in principle should be treated surgically if there is no contraindication to surgery. 2) benign thyroid nodules, which can be treated conservatively with regular follow-up to avoid surgical treatment, but surgery should be considered for those with
1）Cancerous changes are clinically considered
(2) The presence of compression symptoms, such as respiratory, gastrointestinal, and nerve compression
(3) post-thoracic goiter and tendency to fall down into the mediastinum
4) Combined hyperthyroidism (gradually replaced by radioactive 131I treatment)
5）Serious cosmetic impact, large masses
6) Patients with excessive concerns affecting their normal life
The clinical differential diagnosis of nodules is often focused on whether they are benign or malignant. At present, the incidence of thyroid cancer is increasing year by year both at home and abroad. The reason for this is unknown and may be due to the increased incidence of physical examinations and ultrasound. According to the findings of autopsy, 36% of normal deaths have thyroid microcarcinoma, which means that some people have no progression for life. Therefore, there is no need to be overly concerned about this increased incidence, as it is not yet conclusive.
How to identify potentially malignant cases among common thyroid nodules is a greater challenge for clinicians. The differential diagnosis can be made by the following means.
I. History and physical examination
Medical condition, disease duration, thyroid function; history of head and neck radiation, family history of thyroid tumor.
Physical examination can reveal abnormal thyroid enlargement, size, number, texture of nodules, cervical lymph nodes, thyroid nodules with hoarseness, dyspnea, dysphagia, abnormal enlarged lymph nodes in the neck, etc. are clinical evidence of malignancy. Traditionally, risk factors for malignant thyroid nodules include hard, fixed nodules, rapid growth, enlarged cervical lymph nodes, hoarseness, dysphagia, head and neck radiation exposure, and family history of medullary thyroid carcinoma or multiple endocrine adenomatosis type 2.
Laboratory tests
Significantly elevated serum calcitonin and cea levels suggest medullary carcinoma M TC. For patients with a family history of M TC or M EN 2, the basal or post-stimulation serum calcitonin level should be measured.
III. Imaging examination
Ultrasonography (U S) High-definition thyroid ultrasonography is the most widely used clinical test to evaluate thyroid nodules, which can accurately detect the size and number of thyroid nodules, and is also sensitive to thyroid nodules that are not palpable during physical examination or even 1 ~ 2 mm lesions. Ultrasound evaluation of the thyroid gland is recommended for all patients with palpable thyroid nodules, in addition to screening ultrasound in patients with high-risk multinodular goiter (familial thyroid cancer, M EN 2 or radiation exposure). Ultrasound is also useful to identify the nature of the nodule. Ultrasound features suggestive of malignant nodules include: (1) microcalcifications; (2) irregular nodule margins or microlobular margins without a halo; (3) intra-nodular flow disturbances (rich vascularity, disorganized distribution, curved and branched vessels); (4) hypoechoic nodules; (5) extrathyroidal invasion or enlargement of cervical lymph nodes with loss of lymph node portal structures, cystic changes, or micro (6) anterior and transverse diameters of the lesion are greater than the anterior and transverse diameters.
diam eterratio (A/T≥1). The above single features cannot distinguish benign from malignant and require a comprehensive diagnosis by an experienced ultrasonographer.
1.2 Thyroid imaging reporting and data system (TI-RADS)
With the in-depth development of thyroid disease work, in order to strengthen the communication between ultrasound and clinical and to facilitate the interpretation of thyroid ultrasound reports, it is proposed to standardize thyroid ultrasound reports, and currently our hospital adopts a unified reporting conclusion system, TI-RADS. This system divides thyroid ultrasound image conclusions into the following five categories.
TI-RADS
Ultrasound Image Indication
Risk of malignancy (m)
Clinical recommendations
1
Normal thyroid with no lesions
m=0
2
Diagnosable benign lesions
m=0
Long-term (12 months) interval follow-up
3
Benign potentially large lesions
m≤3
Medium to long term (6 months) interval follow-up
4A
Lesions with some possibility of malignancy
3
If biopsy results are negative, continue short-term follow-up
4B
Lesions with considerable malignant potential
30
If biopsy results are negative, repeat puncture at short intervals, or consider surgery
4C
Lesions with great malignant potential
60 < m ≤ 95
Surgical treatment is preferred
Second choice of surgical treatment after fine needle aspiration biopsy
5
Diagnosable malignant lesions
m > 95
Immediate surgical treatment
1.3 In recent years, ultrasound elastography has further improved the level of identification by assessing the hardness of the tissue to identify thyroid cancer, also known as “electronic palpation”, but attention should be paid to factors that may cause false positives or false negatives: for example, coarse calcifications within the nodule may cause false positives, and the large size of the mass may also make elastography inaccurate. The size of the mass may not accurately reflect the softness of the mass and surrounding tissue. Because of the atypical nature of some of the lesions, the nature of the nodule cannot be determined completely by ultrasound technology, and ultrasound-guided FN A may be performed.
2. Other thyroid scintigraphy can evaluate the function of the nodule. “Hot nodules are benign in 99% of cases, while cold nodules are malignant in 5%-8% of cases. It is not very helpful.
CT and MRI are not as cost-effective as thyroid ultrasound in determining the nature of the nodule, but they are valuable in assessing the relationship between the nodule and the surrounding tissues, and in assessing retrosternal goiter. In addition, CT is a more objective examination and has a higher value for the presence or absence of metastasis in lymph nodes.
4. FN A valid and reliable method to identify benign and malignant thyroid nodules. The diagnostic accuracy of FN A can reach 95% through the efforts of experienced operators and cytopathologists, and the results of FN A are classified as: ① benign (70%); ② malignant (5%-10%); ③ suspected malignant (10%); ④ unsatisfactory sampling cannot be diagnosed (5%-15%). Unsatisfactory sampling is related to the operator’s inexperience, too large or too small lesions, and combined cystic lesions, etc. With the popularization of ultrasound-guided FNA, the diagnostic rate has further improved. However, it is still controversial whether it is a complete substitute for intraoperative pathology.
The following diagram shows the common process of differentiating benign and malignant nodules in our hospital
In conclusion, thyroid nodules are common clinical lesions, not diagnoses, and generally require comprehensive evaluation by experienced physicians based on examinations to select cases that require treatment. The final diagnosis only relies on post-surgical pathological examination.
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The individualized selection of minimally invasive thyroid surgery