Benign follicular nodule

by Adnan Karavelic MD FRCPC
October 18, 2022

What is a benign follicular nodule in the thyroid gland?

The term ‘benign follicular nodule’ is used to describe a group of non-cancerous conditions in the thyroid gland. All the conditions in this group are made up of specialized follicular thyroid cells that look similar when examined under the microscope.

What causes a benign follicular nodule?

There are several conditions that can cause a benign follicular nodule in the thyroid gland. These conditions include nodular thyroid hyperplasia (also known as nodular follicular disease), an adenomatoid nodule, and a follicular adenoma. Diffuse papillary hyperplasia (Graves disease) can also result in the development of multiple benign follicular nodules.

What are the symptoms of a benign follicular nodule?

Patients with a benign follicular nodule typically have an enlarged thyroid gland. The enlarged thyroid can often be seen or felt on the front of the neck. Very large nodules or the presence of multiple nodules can lead to difficulty breathing, especially when lying down.

Does a benign follicular nodule need to be removed?

Most patients with a diagnosis of benign follicular nodule will not need any additional treatment. However, surgery to remove part or all of the thyroid gland may be required if the enlarged gland starts to put pressure on surrounding tissues. Talk to your doctor about the next steps in your care.

How is the diagnosis of benign follicular nodule made?

This diagnosis is usually made after a procedure called a fine needle aspiration (FNAB) is performed on a lump or nodule in the thyroid gland. This tissue is sent to a pathologist who examines it under a microscope.

What do the cells in a benign follicular nodule look like under the microscope?

When examined under the microscope, the tissue sample typically shows follicular cells arranged in solid, flat groups called sheets. The follicular cells may also form small, round structures, called microfollicles, but this pattern tends to involve only a small amount of the tissue sample. A variable amount of colloid is typically present in the background. The follicular cells may be described as having small, round to oval nuclei, uniformly granular chromatin, smooth nuclear membranes, and a moderate amount of cytoplasm. Some of the follicular cells will be larger and bright pink. Pathologists call these Hurthle cells. In addition, specialized immune cells such as macrophages and lymphocytes may also be seen in the tissue sample. These cells are typically seen in small groups or scattered throughout the background. All the microscopic features described in this section are non-cancerous changes that support the diagnosis of a benign follicular nodule. However, they cannot be used to distinguish between specific conditions within the group.

Benign follicular nodule. This picture shows follicular cells from a sample diagnosed as a “benign follicular nodule”.

Other helpful resources

American Thyroid Association