Follicular Nodular Disease of the Thyroid Gland: Understanding Your Pathology Report

by Jason Wasserman MD PhD FRCPC
May 12, 2026

Follicular nodular disease is a benign (noncancerous) condition in which the thyroid gland contains one or more nodules. A nodule is a rounded area where thyroid cells have grown more than usual. The thyroid is a small, butterfly-shaped gland at the front of the neck that helps control metabolism by producing thyroid hormones.

When many nodules are present, the condition is often called a multinodular goiter. Follicular nodular disease is very common, especially in adults, and most people with this condition never develop serious problems.

What are the symptoms of follicular nodular disease?

Most people with follicular nodular disease do not have symptoms. The nodules are often found during a routine physical exam or on imaging done for another reason.

When symptoms do occur, they are usually related to the size or number of nodules, not cancer. Symptoms may include a visible lump or swelling in the neck, a feeling of fullness or pressure, or difficulty swallowing or breathing if the thyroid is enlarged.

Less commonly, some people develop symptoms related to thyroid hormone imbalance, such as fatigue, weight changes, heart palpitations, or sensitivity to heat or cold. These symptoms depend on whether the thyroid is producing too much or too little hormone.

What causes follicular nodular disease?

The exact cause is not always known, but several factors can contribute:

Iodine deficiency. Iodine is needed to make thyroid hormone. When iodine is in short supply, the thyroid can enlarge and form nodules in an attempt to make more hormone.
Genetics. Thyroid nodules and goiter can run in families.
Long-standing thyroid inflammation. Conditions such as Hashimoto’s thyroiditis (an autoimmune condition in which the immune system attacks the thyroid) can promote nodule development.
Long-term thyroid stimulation. Prolonged stimulation of the thyroid by thyroid-stimulating hormone (TSH) can encourage nodular growth over time.

How is the diagnosis of follicular nodular disease made?

The diagnosis is usually made using a combination of clinical evaluation, imaging, and sometimes tissue sampling. Doctors often first detect nodules during a physical exam of the neck. A thyroid ultrasound is then used to assess the size, number, and appearance of the nodules; ultrasound cannot diagnose cancer on its own, but it helps identify nodules that may need closer evaluation. If a nodule has concerning ultrasound features or is large, a fine-needle aspiration (FNA) biopsy may be performed. This involves using a thin needle to collect cells for microscopic examination. If part or all of the thyroid is removed surgically, a pathologist examines the tissue to confirm the diagnosis and to rule out cancer. Blood tests are also often performed to check thyroid hormone levels and confirm that the thyroid is functioning normally.

What does follicular nodular disease look like under the microscope?

Under the microscope, follicular nodular disease shows a mixture of normal thyroid tissue and nodules made up of follicular cells (the cells that normally produce thyroid hormone). The nodules are usually well-defined but, unlike true tumors, are not surrounded by a distinct fibrous capsule.

Common findings include:

Hyperplastic follicles. Enlarged or irregularly shaped follicles (the small round structures inside the thyroid that store thyroid hormone).
Abundant colloid. Colloid is the thick, gel-like material normally stored inside follicles. In follicular nodular disease, colloid is often abundant.
Degenerative changes. These are signs of aging or wear within the nodule rather than cancer. They include fibrosis (scar-like tissue), cyst formation (fluid-filled spaces), hemorrhage (bleeding), calcifications, and collections of immune cells that clean up old blood. These findings are common and expected in long-standing benign thyroid nodules.

What is the risk of cancer in follicular nodular disease?

Follicular nodular disease is itself a noncancerous condition. However, like any thyroid gland, a thyroid gland affected by follicular nodular disease can also develop cancer separately. If a cancerous tumor is identified, it will be described separately and clearly in the pathology report.

The overall risk of thyroid cancer is low, but it is not zero. For this reason, doctors pay special attention to nodules that grow quickly, feel firm or fixed, or have suspicious features on ultrasound. A history of radiation exposure to the head or neck, especially during childhood, also increases concern. If any concerning features are present, additional testing such as a repeat ultrasound, biopsy, or surgery may be recommended.

What is the difference between follicular nodular disease and a goiter?

A goiter simply means that the thyroid gland is enlarged. Follicular nodular disease refers specifically to the presence of one or more nodules within the thyroid. When a thyroid gland is enlarged and contains multiple nodules, the term multinodular goiter is often used. The two terms are closely related but not identical: a goiter does not always contain nodules, and a thyroid with follicular nodular disease is not always visibly enlarged.

What does it mean if a dominant adenomatoid nodule is present?

A dominant adenomatoid nodule is the largest nodule within a thyroid containing multiple nodules. Adenomatoid nodules are benign, but they often receive closer attention because they are more likely to cause symptoms (such as a visible lump or pressure in the neck) or to look suspicious on imaging. Your pathologist carefully examines the dominant nodule to make sure there are no features of cancer or precancerous change.

What happens after the diagnosis?

Most people with follicular nodular disease do not need any treatment and are simply monitored with regular check-ups and, sometimes, periodic ultrasound. Possible approaches include:

Observation. The most common approach when the thyroid is not significantly enlarged, thyroid hormone levels are normal, and there are no suspicious features. Follow-up usually involves periodic clinical examination and, if recommended, an ultrasound.
Thyroid hormone medication. If blood tests show that the thyroid is underactive (hypothyroidism), levothyroxine (a synthetic form of thyroid hormone) may be prescribed.
Treatment for an overactive thyroid. If one or more nodules are producing too much thyroid hormone (a condition called toxic nodular goiter), treatment options include antithyroid medication, radioactive iodine, or surgery.
Surgery. Surgery may be recommended when the thyroid is very large and causing trouble swallowing or breathing, when a nodule cannot be reliably distinguished from cancer, or when imaging or biopsy findings raise concern.

Regular follow-up is important because thyroid nodules can change over time. Any new symptoms, rapid growth of a nodule, or change in voice should prompt evaluation.

Questions to ask your doctor

Do I have a single thyroid nodule or multiple nodules?
Was there a dominant nodule, and what does it look like under the microscope?
Are my thyroid hormone levels normal?
Do I need treatment, or is monitoring enough?
How often should my thyroid be checked with examination, blood tests, or ultrasound?
Are there any features in my report that raise concern for cancer?
Should I avoid anything, such as iodine supplements or certain medications?