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

by Jason Wasserman MD PhD FRCPC
May 13, 2026

Diffuse papillary hyperplasia of the thyroid gland is a benign (noncancerous) change seen in thyroid tissue, most commonly in people with Graves’ disease. The thyroid is a small, butterfly-shaped gland at the front of the neck that produces hormones to regulate metabolism. 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, follicular cells (the cells that normally make thyroid hormone) grow in a papillary (finger-like) pattern throughout the gland. In this setting, the word papillary describes the shape of the growth only and does not indicate cancer. Diffuse papillary hyperplasia does not form a true tumor, does not invade surrounding tissue, and does not spread to other parts of the body.

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, even when the body does not need more thyroid hormone. This stimulation causes the follicular cells to grow and divide more than normal. Over time, this leads to widespread enlargement of the thyroid (a goiter) and the development of papillary-shaped growths within the gland.

Importantly, this process is driven by immune stimulation rather than by cancer-causing genetic changes within the thyroid cells. That is why diffuse papillary hyperplasia is considered a reactive (responsive) change rather than a tumor.

What are the symptoms of diffuse papillary hyperplasia?

The symptoms of diffuse papillary hyperplasia are usually the symptoms of Graves’ disease and an overactive thyroid (hyperthyroidism), rather than of the microscopic growth pattern itself. Common symptoms include:

Weight loss despite normal or increased appetite.
Heat intolerance and excessive sweating.
A fast or pounding heartbeat (palpitations).
A fine trembling of the hands (tremor).
Anxiety or irritability.
Fatigue and muscle weakness.
Enlargement of the thyroid gland (goiter).

Diffuse papillary hyperplasia is usually identified only after thyroid tissue is examined under a microscope, most often following thyroid surgery to treat Graves’ disease.

How is the diagnosis of diffuse papillary hyperplasia made?

The diagnosis is made by examining thyroid tissue under a microscope, usually after part or all of the thyroid gland has been removed by surgery to treat Graves’ disease. The pathologist sees the characteristic growth pattern (described in the next section) throughout the gland, often in a setting of a known clinical diagnosis of Graves’ disease. Blood tests showing high thyroid hormone levels and the presence of antibodies against the thyroid-stimulating hormone receptor (TSI or TRAb) support the underlying diagnosis of Graves’ disease and help the pathologist place the microscopic findings in context.

What does diffuse papillary hyperplasia look like under the microscope?

Under the microscope, diffuse papillary hyperplasia shows several characteristic features:

Widespread papillary growth. Finger-like projections of tissue are seen throughout the thyroid gland rather than in just one area.
Tall, crowded follicular cells. The cells lining the papillary structures are taller than normal and packed closely together.
Diffuse involvement. The change is uniformly distributed across the thyroid rather than forming a single lump or mass.
No invasion. The cells do not grow into surrounding thyroid tissue, blood vessels, or lymphatic channels.
Reduced colloid. Colloid (the thick, gel-like material that the thyroid uses to store hormone) is often scant because the overactive gland is releasing hormone faster than it can be stored.

Is diffuse papillary hyperplasia cancer?

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

Because the word “papillary” also appears in the name of a common thyroid cancer called papillary thyroid carcinoma, the two diagnoses can sound similar. They are very different conditions. Papillary thyroid carcinoma forms a discrete tumor with cells that show specific changes in the nucleus (the part of the cell that holds the genetic material) and can invade surrounding tissue and spread to lymph nodes. Diffuse papillary hyperplasia involves the whole gland, lacks those distinctive nuclear changes, and does not invade or spread. Pathologists carefully review the microscopic features to make sure the two are not confused.

What happens after the diagnosis?

Because diffuse papillary hyperplasia is a reactive change rather than a tumor, no treatment is directed at the hyperplasia itself. Management focuses on the underlying Graves’ disease, which may include antithyroid medications, radioactive iodine, or surgery, depending on the clinical situation. If the thyroid has already been removed, follow-up care is usually coordinated by an endocrinologist and centers on thyroid hormone replacement and monitoring of thyroid function. No additional cancer screening is needed because of the hyperplasia.

Questions to ask your doctor

Was this finding expected given my Graves’ disease?
Does this diagnosis require any additional treatment or follow-up?
How will my thyroid function be monitored going forward?
Do I need any monitoring for thyroid cancer because of this finding?
Should any of my family members be tested for Graves’ disease?