Diffuse Papillary Hyperplasia of the Thyroid Gland: Understanding Your Pathology Report

by Jason Wasserman MD PhD FRCPC
January 20, 2026

Diffuse papillary hyperplasia of the thyroid gland is a benign (non-cancerous) change seen in thyroid tissue, most commonly in people with Graves’ disease. Graves’ disease is an autoimmune condition in which the immune system produces antibodies that overstimulate the thyroid gland, leading to its enlargement and excess thyroid hormone production.

In response to this ongoing immune stimulation, thyroid cells can grow in a papillary (finger-like) pattern throughout the gland. In this setting, the word papillary describes the growth’s shape only and does not indicate cancer. This condition does not form a true tumour, does not invade surrounding tissue, and does not spread to other parts of the body.

This article explains what diffuse papillary hyperplasia of the thyroid gland means, why it occurs in Graves’ disease, and how pathologists recognize it in a pathology report.

Where does this condition start?

Diffuse papillary hyperplasia starts in the follicular cells of the thyroid gland. These are the normal cells that produce and store thyroid hormone.

Under usual conditions, follicular cells form round structures called follicles. In diffuse papillary hyperplasia, these same cells grow into papillary projections inside the follicles across much of the gland, rather than forming a discrete mass.

What causes diffuse papillary hyperplasia?

The most common cause of diffuse papillary hyperplasia is Graves’ disease. In Graves’ disease, the immune system produces antibodies that continuously stimulate the thyroid gland. This stimulation causes the follicular cells to grow and divide more than normal. Over time, this leads to widespread enlargement of the thyroid (goitre) and the development of papillary-shaped growths within the gland.

Importantly, this process is driven by immune stimulation, not by cancer-causing genetic mutations within the thyroid cells.

What are the symptoms?

The symptoms of diffuse papillary hyperplasia are related to hyperthyroidism (excess thyroid hormone) rather than the microscopic growth pattern itself.

Common symptoms include:

• Weight loss despite normal or increased appetite.

• Heat intolerance and excessive sweating.

• Palpitations or rapid heartbeat.

• Tremor.

• Anxiety or irritability.

• Fatigue and muscle weakness.

• Enlargement of the thyroid gland (goitre).

Diffuse papillary hyperplasia is usually identified after thyroid surgery performed to treat Graves’ disease.

How is this diagnosis made?

The diagnosis is made by examining thyroid tissue under a microscope, typically after partial or total thyroid gland removal.

Microscopic features

When viewed under the microscope, diffuse papillary hyperplasia shows:

• Widespread papillary growth throughout the thyroid gland.

• Tall, crowded follicular cells lining papillary structures.

• Uniform involvement rather than a single lump or tumour.

• No invasion into the surrounding thyroid tissue, blood vessels, or lymphatic channels.

Although the papillary shape may resemble patterns seen in thyroid cancer, the overall architecture and cell features support a benign, reactive process related to Graves’ disease.

Is diffuse papillary hyperplasia cancer?

No. Diffuse papillary thyroid hyperplasia is not cancer. It does not behave like cancer, does not spread, and does not increase the risk of thyroid cancer on its own.

The papillary growth pattern reflects a reactive response to immune stimulation rather than malignant transformation.

What happens after the diagnosis?

Management focuses on treating Graves’ disease, which may include medications, radioactive iodine, or surgery, depending on the clinical situation. If the thyroid has already been removed, follow-up care is directed by your endocrinologist and is based on thyroid hormone replacement and overall thyroid function.

Questions to ask your doctor

• Was this finding related to my Graves’ disease?

• Does this diagnosis require any additional treatment or follow-up?

• How does this affect my long-term thyroid care?

• Do I need monitoring for thyroid cancer because of this finding?