Types of thyroid diseases

The article was written by Specialist Doctor I Nguyen Thi Minh Thuyen - Pathologist, Laboratory Department - Vinmec Danang International General Hospital.

Cancer begins when cells grow out of control. Thyroid cancer is a type of cancer that originates in the thyroid gland. Different types of cancer originate from different types of cells. This is important because they affect the severity of the cancer and how it is treated.

The thyroid gland is located in the front part of the neck, below the thyroid cartilage (Adam's apple), and is usually not seen or felt. The thyroid gland is shaped like a butterfly, with 2 lobes - right and left - connected by a small gland in the middle, the isthmus.

The thyroid gland produces hormones that help regulate metabolism, heart rate, blood pressure, and body temperature. The thyroid gland has two main types of cells: Follicular cells: use iodine from the blood to produce thyroid hormone, which helps regulate the body's metabolism. Hyperthyroidism can cause a fast or irregular heartbeat, trouble sleeping, nervousness, hunger, weight loss, and a feeling of heat. Low hormones (hypothyroidism) cause the body to slow down, feel tired and gain weight. The amount of thyroid hormone secreted is regulated by the pituitary gland at the base of the brain, which produces a substance called thyroid stimulating hormone (TSH). C cells (parafollicular cells) secrete calcitonin, a hormone that helps the body regulate calcium. Other cells are less numerous, including immune system cells (lymphocytes) and support cells (stromal tissues).

The thyroid gland has a variety of proliferative and neoplastic pathologies. Most are benign (not cancerous) but the rest are malignant (cancerous), which means they can spread into nearby tissues and to other parts of the body.
1. Benign thyroid disease 1.1. Thyroid enlargement Changes in the size and shape of the thyroid gland can often be felt or seen.
An abnormally large thyroid gland is sometimes called a goiter. Some goiters are diffuse, meaning the entire thyroid gland is enlarged. Other goiters are nodules, which means the thyroid gland is large and has one or more thyroid nodules. There are many reasons the thyroid gland may be larger than normal and most often it does not progress to cancer.
Both diffuse goiter and nodular goiter are usually caused by an imbalance of certain hormones. For example, a diet lacking in iodine can cause changes in hormone levels and lead to a goiter.
1.2. Thyroid nodules Tumors in the thyroid gland are called thyroid nodules. Most thyroid nodules are benign, but about 2 or 3 out of 20 are cancerous. Sometimes these nodules make too much thyroid hormone and cause hyperthyroidism. Thyroid nodules that produce too much thyroid hormone are almost always benign.
Thyroid nodules can occur at any age, but are more common in adults. Less than 1 in 10 adults have palpable thyroid nodules. But on thyroid ultrasound, many nodules that are too small to be felt are detected and most are benign.
Most nuclei are fluid-filled cysts called thyroid colloid. Solid nodules have little thyroid fluid or colloid and may be cancerous. However, most solid nodules are not cancerous. Some solid nuclei, such as hyperplastic nuclei and adenomas, have many cells, but are not cancerous.
Benign thyroid nodules may not require treatment and close monitoring as long as they do not develop or cause symptoms, or may require some form of treatment.

2. Types of thyroid cancer The main types of thyroid cancer are:
Differentiated cancer (including papillary, follicular and Hürthle cell) Medullary cancer Undifferentiated cancer (anaplastic - a type of cancer) high-grade malignancy 2.1.differentiated thyroid cancers Most thyroid cancers are differentiated cancers, where the cancer cells look a lot like normal thyroid tissue, which is the type of cancer that originates. from follicular cells.
Papillary carcinoma: About 8 out of 10 thyroid cancers are papillary cancers. This type of cancer tends to grow very slowly and is usually in one lobe of the thyroid gland. Although slow growing, papillary cancers tend to spread to the lymph nodes in the neck. But even when they have spread to the lymph nodes, they can be successfully treated and are rarely fatal.
There are several subtypes of papillary cancers, of which the cystic (follicular variant) subtype is the most common, and have the same treatment and good prognosis as classical papillary cancers when detected. show up early. Other subtypes of papillary cancers (pillar cell, tall cell, islet, and diffuse sclerosis) are less common and tend to grow and spread more rapidly. Follicular carcinoma is the most common type after papillary cancer, about 1 in 10 thyroid cancers. This type is more common in countries where there is not enough iodine in the diet. This type of cancer usually does not metastasize to the lymph nodes, but can spread to other organs, such as the lungs or bones. Prognosis remains good in most cases, although not as good as papillary cancers.
● Hürthle cell carcinoma (Hürthle cell carcinoma): accounts for about 3% of all thyroid cancers. This type of cancer is often more difficult to diagnose and treat.
2.2.Medullary thyroid carcinoma (MTC) Medullary thyroid cancer (MTC) accounts for about 4% of all thyroid cancers, originating in the C cells of the thyroid gland (C cells). produce calcitonin, a hormone that helps control blood calcium levels). Sometimes this type of cancer can spread to the lymph nodes, lungs, or liver even before a thyroid nodule is detected.
Medullary thyroid cancer is more difficult to diagnose and treat. There are 2 types of MTC:
● Spontaneous MTC (sporadic MTC): accounts for about 8 out of 10 cases of MTC, is not hereditary, occurs mainly in the elderly and usually affects only one lobe of the thyroid gland.
Familial MTC : is inherited, and usually occurs in generations of a family. This type of cancer usually develops at a young age and can spread early, often affecting both lobes of the thyroid gland. Familial MTC is often associated with an increased risk of several other tumors.

2.3. Anaplastic (undifferentiated) thyroid cancer is a rare form of thyroid cancer that accounts for about 2% of all thyroid cancers. It is called undifferentiated because of the cancer cells. do not look like normal thyroid cells. This cancer often progresses rapidly into the neck and other organs, is highly aggressive, and is difficult to treat.
2.4. Less common types of thyroid cancer Less than 4% of thyroid cancers are lymphoma, thyroid sarcoma, or other rare tumors.
When we notice abnormalities in the body, we need to go to the doctor immediately, have a general examination as well as a specialist to detect the disease as soon as possible. Doctors recommend that we go for a regular check-up once a year to understand our health status, as well as have a direction to screen for early treatment.
For thyroid cancer, we need to perform subclinical diagnostic methods such as thyroid ultrasound, cytological diagnostic tests to detect thyroid cancer.

Article referenced source: American Cancer Society