Thyroid nodules are a very common disease. However, more than 90% of thyroid nodules are found to be benign lesions and only 4.0% to 6.5% are cancerous.

According to GLOBOCAN 2020, there are over 586,000 new thyroid cases and nearly 44,000 deaths worldwide. In Vietnam (2020) thyroid cancer ranks 10th with about 5,500 new cases and 650 deaths each year. Thyroid nodules are about 4 times more common in women than in men. A 20-year surveillance study estimated prevalence rates to be 0.8% and 5.3% in men and women, respectively.

What is a thyroid nodule?

What is Thyroid Tumor? Thyroid nodules , also known as thyroid nodules. These are solid or liquid nodules/masses that form within the thyroid parenchyma. The thyroid is a small gland located in the anterior neck region, just above the breastbone.

Most thyroid nodules are not serious and cause no symptoms, making them difficult to detect. Instead, it is often discovered by accident during routine physical examination through ultrasound of the neck. Thyroid nodules are usually benign, but a few are cancerous. A thyroid nodule presents with symptoms when it has grown large and compresses and makes breathing and swallowing difficult.

Classification of thyroid tumors

Thyroid nodules can be classified as cancerous and noncancerous.


Thyroid cancer can be classified as follows:

  • Differentiated thyroid cancer (DTC): includes papillary thyroid cancer, follicular thyroid cancer, and mixed papillary and follicular thyroid cancer: Arises from epithelial cells and accounts for about 95 % of all thyroid malignancies.
  • Medullary thyroid cancer (MTC): arises from the calcitonin-producing follicular cells of the thyroid gland. 20% of MTC is genetically related and can occur as part of multiple endocrine neoplasia (MEN) syndromes.

No cancer

Most thyroid nodules/tumors are benign. Can be thyroid cyst, mixed cyst, thyroid tumor, thyroiditis, etc.

Thyroid tumor symptoms

Doctors say that most thyroid nodules/tumors cause no signs or symptoms, so the signs of thyroid nodules are not obvious. But sometimes some large tumors can cause signs of thyroid nodules .

Signs of a thyroid nodule include:

  • Tumor in the anterior neck area is visible.
  • Tumor presses on recurrent vocal cords causing hoarseness
  • The tumor presses on the windpipe or esophagus, making it difficult to breathe or swallow.
  • Hyperthyroidism with symptoms: unexplained weight loss, increased sweating, tremors, anxiety, fast or irregular heartbeat, irregular or missed periods, diarrhea and more frequent urination, increased appetite taste.
  • Symptoms of hypothyroidism: Fatigue, numbness and tingling in the hands, weight gain, dry, rough skin and hair, constipation, depression, heavy and frequent menstrual periods.

Complications of thyroid tumors

Complications of thyroid nodules can include:


Symptoms of hyperthyroidism can be a complication in patients with overactive thyroid nodules. A thyroid tumor/nodule increases thyroid hormone production , resulting in excess hormone levels in the body.

Clinical manifestations will include manifestations of hyperthyroidism, such as sweating, palpitations and impaired glucose tolerance, weight loss, muscle weakness, bone weakness, heat intolerance, anxiety or irritability Horror, thyrotoxicosis crisis. However, the majority of thyroid nodules are benign and most patients will be asymptomatic.

Difficulty swallowing

A small number of patients, especially those with thyroiditis, may experience neck pain, swelling, and difficulty swallowing and breathing.

Thyroid tumor causes

To date, the cause of thyroid nodules is unknown, but the following risk factors are thought to cause it.

Ionizing radiation

Ionizing radiation is a known risk factor for both benign and malignant thyroid nodules. People exposed to ionizing radiation may develop thyroid nodules at an annual rate of 2%. A high rate of malignancy has been reported, accounting for 20-50% of palpable nodules of previously irradiated thyroid glands.

Iodine deficiency or excess iodine

Iodine deficiency or excess iodine in your diet can sometimes cause the thyroid gland to develop thyroid nodules.

Other factors

Other factors that lead to an increased risk of thyroid nodules and goiter include:

  • Smoke
  • Fat
  • Metabolic syndrome
  • Drink alcohol
  • Increased levels of insulin-like growth factor-1 (IGF-1)
  • Fibroids

How to diagnose thyroid nodules?

Initial evaluation for patients with thyroid nodules includes taking personal and family history, physical exam, testing for thyroid hormone (FT3, FT4), thyroid-stimulating hormone (TSH), and thyroid ultrasound to characterize thyroid nodules.

After ultrasound detects nodules or thyroid nodules, the doctor will order fine needle aspiration of the thyroid nodules/tumors under the guidance of ultrasound to increase the accuracy of cytology, identify Tumor nature is benign or malignant to guide management and treatment. In some cases, genetic testing, immunohistochemical markers as well as further evaluation are required: elastography, MRI, CT and FDG-PET/CT.

Thyroid stimulating hormone (TSH) test

In each patient with a thyroid nodule, the thyroid-stimulating hormone (TSH) test should be the initial test and be used as a guide for later management.

Normal or high levels of thyroid-stimulating hormone are often cause for concern due to the risk of malignancy. However, low levels of thyroid-stimulating hormone are usually a benign nodule.

The next step in a patient with low thyroid-stimulating hormone levels is to evaluate the possibility of thyrotoxic nodules (hyperfunctioning thyroid nodules) by scintigraphy of the thyroid with Tc-99m or Iodine 131. Self-active thyroid nodules are usually benign and rarely require further diagnosis.

Thyroid ultrasound

Thyroid ultrasound is an important imaging technique used to evaluate thyroid nodules. This method provides information on size, structure, and parenchymal changes and can detect lesions as small as 2 mm.

Thyroid ultrasound is often used to differentiate between benign and malignant lesions and avoid unnecessary invasive procedures.

Several features that are associated with malignancy and are considered independent risk factors include microcalcifications, irregular margins, strong hypoechoic, greater height than width, and vascular proliferation.

Thyroid ultrasound is highly sensitive in detecting small thyroid nodules that are difficult to detect by palpation.

Fine Needle Aspiration (FNA)

FNA forms the basis for the evaluation of thyroid nodules, representing the most cost-effective diagnostic tool used in the evaluation of thyroid nodules. The use of ultrasound-guided FNA is preferred over no ultrasound-guided one because of its relevance to accuracy and false-negative results rates.

The decision to perform FNA should be based on individual risk stratification using the patient’s history, physical examination, and ultrasound findings. Nodules <1cm are FNA in the presence of more than one suspicious feature of ultrasound, cervical lymphadenopathy, or high-risk history.

Diagnostic cytology

The U.S. National Cancer Institute recommends, using the Bethesda classification, stratify cytological findings into 6 major categories, each of which indicates different subsequent assessment and management.

The diagnostic classifications of the Bethesda system for reporting thyroid cytology are described as follows:


The sample does not have an adequate number of cells for evaluation.


May be: Normal, benign thyroid tissue, or nodules, or Hashimoto’s thyroiditis and subacute granulomatous thyroiditis.

Lesions of undetermined significance (AUS ) or follicular lesions of undetermined significance (FLUS )

Recommended for convincingly non-benign lesions. AUS shows lesions presenting with nuclear loss and lesions with extensive cytological changes. Although they are not sufficient to be classified as Hürthle cell carcinoma. FLUS displays a combined microfollicular and macrofollicular pattern.

Cystic neoplasia or suspected cystic neoplasia

Cysts or suspected cystic cancer including adenomas or microcysts. Because FNA samples only a portion of the nodule, surgical resection of the tumor should be considered to determine whether the microcystic lesion is benign or malignant.

Suspected malignancy

Suspected malignancy when some malignancy features are present but not sufficient for diagnosis

diagnosis of malignancy.

Malignant disease

The cytology will be different for the types of malignant thyroid tumors that can be:

  • Papillary thyroid cancer and variants
  • Medullary thyroid cancer
  • Poorly differentiated thyroid cancer
  • Undifferentiated thyroid cancer
  • Metastatic thyroid cancer and lymphoma

Differential diagnosis

Although most thyroid nodules and neoplasms are usually benign, patients should still be monitored and diagnosed to rule out malignancy, especially in patients at risk for thyroid cancer.

Tumors in the anterior neck area can be benign subcutaneous tumors (poxoma, lipoma…) not in the thyroid gland, may be inflammatory lymph nodes, may be metastatic lymph nodes from other cancers in other regions. head and neck cancer, esophageal cancer, lung cancer, stomach cancer…

How to treat thyroid nodules ?

Initial management of thyroid nodules depends on the type of lesion found, the characteristics of the ultrasound, and whether it is functional. The final FNA results will guide treatment.

FNA cytology results provide 6 major diagnostic classifications (Bethesda classification), all of which indicate different subsequent management.

  • Undiagnosed: 1-4% cancer risk.
  • Benign: Risk of cancer 0-3%.
  • Lesions of undetermined significance or cystic lesions of undetermined significance: 5-15% cancer risk.
  • Cystic neoplasia or suspected cystic neoplasia: 15-30% cancer risk.
  • Suspected malignancy: 60-75% cancer risk.
  • Malignant: Risk of cancer 97-99%.

Non-diagnostic biopsy (Bethesda I) was considered cytologically inadequate. The absence of malignant cells should not be interpreted as a negative biopsy if little cystic tissue is obtained. FNA is usually repeated after 4-6 weeks.

Patients with benign nodules (Bethesda II), such as large tumors, colloid adenomas, nodular goiters, and Hashimoto’s thyroiditis, are often followed up without surgery. Periodic follow-up with initial ultrasound from 12-24 months. If ultrasound reveals suspicious findings, then FNA should be repeated within 12 months even though the initial biopsy was benign.

For nodules with indeterminate cytology (Bethesda III and IV), the approach varies according to institutional practice. Some facilities take additional FNA samples for further testing, while others repeat the FNA after 6-12 weeks.

For nodules in the Bethesda V classification, suspected of being malignancy, treatment should include surgery. Bethesda VI includes papillary, medullary, undifferentiated, and metastatic thyroid cancers. These patients should also be referred for surgery.

Prognosis in patients with thyroid nodules

Most thyroid nodules are benign. Certain patients with high-risk factors such as normal to high serum thyroid-stimulating hormone (TSH) levels, history of irradiation, or multiple endocrine neoplasia (MEN) syndrome should be monitored. more closely periodically. Certain sonographic features may also raise concerns about thyroid cancer such as microcalcifications and irregular margins, wider elevation, and vascular proliferation.

Although solitary nodules have a higher risk of malignancy than nodules in multinodular thyroid nodules, the overall risk of malignancy will be approximately equal. This is due to the cumulative risk of each nodule in patients with multinodular glands.

The prognosis for thyroid malignancies will vary widely depending on the histopathological type of the cancer. In addition, several individual features are also associated with prognosis of malignant thyroid cancer such as age at diagnosis, size of primary tumor, presence of soft tissue invasion or distant metastasis.

Other factors associated with increased recurrence or mortality from malignancy include male gender, mediastinal lymph node involvement, and delay in surgical treatment.

Cystic cancer usually occurs in older patients and follows an aggressive course. It is often associated with distant metastases and has a higher mortality rate than papillary thyroid cancer.

Measures to prevent thyroid tumors

To date, the cause of thyroid nodules is still unknown, so there is no way to prevent this disease. However, each person can try to reduce their risk of developing them by managing certain risk factors.

For example, if you are obese, try to lose weight; if you smoke, quit; Make sure you have enough iodine in your daily diet.

In addition, studies have shown that people who use oral contraceptives and/or statins have a reduced risk of developing thyroid nodules. Therefore, the use of this drug should be limited to prevent the risk of developing thyroid nodules.

Frequently asked questions about thyroid nodules

I have a child with thyroid nodules, what should I do?

Although children are less likely to develop thyroid tumors than adults, the rate of malignancy is higher in children than in adults.

Therefore, when detecting a child with a thyroid tumor, it is necessary to take the child for screening tests to see what type of thyroid tumor the child has (benign or cancerous). The doctor will then recommend the appropriate treatment for the type of thyroid tumor of the child.

What are the possible risks of thyroidectomy?

Patients can face risks when having thyroidectomy such as infection, bleeding, thyroid storm, voice change, thyrotoxicosis, hypocalcemia, hypothyroidism, difficulty swallowing. Therefore, it is important that patients should seek out reputable hospitals with modern equipment, specializing in Oncology, Endocrinology, and Otolaryngology to be coordinated by specialists to bring about effective treatment. high, reduce complications or promptly treat complications if they occur.