Thyroid Biopsies: Everything You Need to Know

Thyroid biopsies are a test that helps to rule out and diagnose the different types of cancers that can occur in this gland. We'll explain what they consist of and how they're performed in this article.
Thyroid Biopsies: Everything You Need to Know

Last update: 08 July, 2021

A thyroid biopsy’s a procedure that’s used very frequently nowadays. It allows specialists to take samples of the gland and analyze them in the laboratory. Doctors can diagnose or rule out numerous diseases, such as cancer, by using thyroid biopsies.

There are different methods of biopsy. The most common use fine needle aspiration, although others help when a clear diagnosis hasn’t been possible.

Thanks to thyroid biopsies, doctors can establish a specific treatment depending on the illness. Therefore, in this article, we’ll explain everything you need to know about this test, how it’s performed and what it’s used for.

What does a thyroid biopsy consist of?

A thyroid biopsy is a procedure used to diagnose different diseases affecting this gland. The thyroid is an organ located in the front part of the neck, in front of the trachea. It’s responsible for producing hormones that play a fundamental role in the control of metabolism.

A thyroid biopsy involves removing a sample of thyroid tissue. Specialists then examine this sample in the laboratory and analyze it under the microscope.

As we’ve pointed out in the introduction, there are different ways of performing it. The most common is fine-needle aspiration biopsy. In these cases, it usually takes place on an outpatient basis using only local anesthesia.

However, other techniques do require general anesthesia and are somewhat more complex. The idea is to obtain part of the tissue of nodules that have appeared. In general, samples are taken from those that can be palpated through the skin.

As a publication in RadiologyInfo states, the nodules from which the sample’s obtained are usually somewhat larger than 1 centimeter. To be able to perform this test in a safer or more specific way, doctors perform an ultrasound scan at the same time. This makes it easier to locate the exact position of the nodules, especially if they’re small.

A digital illustration of a thyroid nodule.
Thyroid nodules are a frequent indication of the need for a biopsy to rule out malignancy.

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Types of thyroid biopsies

There are different ways to perform thyroid biopsies. Generally speaking, there are two types: Puncture biopsies and open biopsies. In the following sections, we’ll explain what each one consists of.

1. Punch thyroid biopsies

A needle biopsy involves needles of different calibers. Within this group, we find the fine-needle aspiration biopsy. This is the most common. According to the Mayo Clinic specialists, doctors use a thin, hollow needle to extract the cells.

It’s usually combined with simultaneous ultrasound to direct the needle to the specific point. This technique takes place in the hospital or the doctor’s office. It takes about 10 minutes and doesn’t require general anesthesia, as it’s a minimally invasive test.

To perform it, the patient must lie on their back, extending their neck. The patient must remain still and quiet during the process, as any movement can interfere with the direction of the needle.

Needle biopsies can also be done with a thick needle. This allows for the taking of samples the size of a grain of rice. It’s important to obtain samples from the different nodules in the gland.

Once the process is complete, the area’s cleaned and a bandage is placed on the points where the needle was introduced. It’s normal for there to be slight discomfort in the area afterward.

2. Open thyroid biopsies

Thyroid biopsies can also take place surgically. In these cases, it’s called an open biopsy. It consists of making a small cut in the neck and removing the nodule or taking a smaller sample to send it to the laboratory.

In some cases, doctors will remove a large part of the gland. Experts recommend this technique when the needle biopsy hasn’t provided an accurate diagnosis.

General anesthesia is necessary for this surgery and it must take place in the operating room. It’s less common because it involves more risks. For example, it increases the possibility of infection, bleeding, and scarring problems.

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Why are thyroid biopsies performed?

The purpose of thyroid biopsies is to determine the cause of a nodule (lump) that appears in the gland. In most cases, doctors detect them beforehand by physical examination. A specialist may also have observed them by ultrasound or scintigraphy.

Thanks to this test, it’s possible to observe the cells that make up the nodule. This makes it possible to check for malignancy and whether or not it’s cancerous.

Thyroid biopsies are also useful for the study of certain cases of goiter. A goiter’s an enlargement of the thyroid.

How to prepare for thyroid biopsies

Before performing a thyroid biopsy, the physician needs to know the patient’s medical history. They must know if the patient’s taking any medication or if they have any other illness. A preliminary examination’s also necessary to locate the nodules.

Certain complementary tests take place before the biopsy. For example, a blood test and an ultrasound scan.

No specific preparation’s required for the needle biopsy. As it’s an outpatient test without general anesthesia, there’s no need to fast beforehand.

If the thyroid biopsy’s open, general anesthesia will be necessary. Since it’s a more complex procedure, doctors will provide specific instructions for the patient. In this case, the patient shouldn’t eat or drink before the procedure. In addition, the patient will need to rest for several hours after the biopsy.

Possible results of a thyroid biopsy

Lab technicians analyzing a thyroid biopsy.
Anatomic pathology analysis of the biopsy specimen allows for the determination of the malignancy of the cells.

A thyroid biopsy provides a great deal of information about the condition of the gland. After analyzing the sample in the laboratory, doctors create an extensive report describing different parameters.

First, they describe the color, consistency, and general appearance. Then they describe the cells that compose it, both in number and morphology. In this way, as the American Thyroid Association explains, the results of a thyroid biopsy can be as follows:

  • Benign: Most biopsies offer this result. They’re nodules that consist of differentiated cells, without atypia. Periodic follow-up usually takes place in the following months and intervention isn’t necessary.
  • Suspected malignancy: This type of result means that certain characteristics point to a diagnosis of malignancy but aren’t conclusive.
  • Malignancy: This is when observable cancer cells are present in the sample. The most common thyroid cancer is papillary thyroid cancer. Treatment usually involves surgery.
  • Atypia of undetermined significance: This is similar to the category of suspected malignancy. However, although there are worrisome features, there are also features that suggest something benign. It’s best to repeat the biopsy if there are doubts.
  • Non-diagnostic: This is when there are insufficient cells to establish an accurate diagnosis.

Biopsies are a fundamental test for cancer

To conclude, we must remember is that, at present, thyroid biopsies are the basic test for diagnosing cancer of this gland. In fact, this type of test not only reveals the presence of malignant cells but also makes it possible to identify the specific type of tumor.

In this way, it makes it possible to establish an appropriate treatment protocol depending on the pathology. Moreover, it’s a test that usually takes place on an outpatient basis and has little risk of complications.

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