Non-invasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP): Understanding Your Pathology Report

by Jason Wasserman MD PhD FRCPC
April 21, 2026

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a noncancerous thyroid tumor that grows slowly and has an excellent outcome after surgery. It develops from follicular cells, the normal cells of the thyroid gland that produce thyroid hormone. The thyroid is a butterfly-shaped gland at the front of the neck.

Although NIFTP cells can look similar under the microscope to those seen in papillary thyroid carcinoma, this tumor does not behave like cancer. Large studies have shown that when NIFTP is completely removed and shows no invasion, patients are cured with surgery alone and do not develop recurrence or spread to other parts of the body.

A note on the name and classification

Before 2016, NIFTP was called “non-invasive encapsulated follicular variant of papillary thyroid carcinoma.” Although the word “carcinoma” (meaning cancer) was used, long-term follow-up studies showed that these tumors behaved in a noncancerous manner as long as no invasion was present.

Based on this evidence, experts changed both the name and the classification to remove the word carcinoma and better reflect how these tumors actually behave. Today, NIFTP is recognized as a distinct, non-cancer diagnosis. The change has spared many patients from unnecessary aggressive treatment, including radioactive iodine therapy.

What are the symptoms of NIFTP?

Most people with NIFTP do not have symptoms. The tumor is often discovered during a routine physical examination as a thyroid nodule or by chance on imaging tests performed for other reasons.

When symptoms do occur, they are usually related to the size of the nodule rather than its behavior. These may include a noticeable lump in the neck, pressure or fullness, difficulty swallowing or breathing, or changes in the voice. These symptoms are not specific to NIFTP and can be caused by many other benign thyroid conditions.

What causes NIFTP?

The exact cause of NIFTP is not fully understood. Like many thyroid tumors, it is thought to develop due to genetic changes in thyroid cells over time. Previous radiation exposure to the head or neck, especially during childhood, is a known risk factor for thyroid tumors in general, but most people with NIFTP have no identifiable cause.

NIFTP is not inherited and does not run in families.

How is the diagnosis of NIFTP made?

A diagnosis of NIFTP can only be made after the entire tumor has been surgically removed and carefully examined under the microscope. This is because the diagnosis depends on confirming that the tumor has not invaded surrounding thyroid tissue or any blood vessels, and this can only be determined by examining the entire tumor. Before surgery, an ultrasound is usually performed and typically shows a well-defined thyroid nodule with a smooth outline, but imaging alone cannot distinguish NIFTP from other follicular-pattern thyroid tumors. A fine needle aspiration (FNA) biopsy is usually performed next, in which a thin needle is used to remove a small sample of cells from the nodule. FNA can show that the nodule is composed of follicular cells and may raise suspicion for NIFTP, but it cannot determine whether invasion is present. For this reason, FNA results in this setting are usually reported using terms such as “follicular neoplasm” or “suspicious for follicular neoplasm,” and surgery is needed to reach a final diagnosis. After surgery, the pathologist examines the whole tumor and its edges under the microscope to confirm that it is follicular-patterned, shows the characteristic nuclear features described below, and has no evidence of invasion.

What does NIFTP look like under the microscope?

Under the microscope, NIFTP has a distinctive combination of features that must all be present to make the diagnosis:

Well-defined border. The tumor is separated from the surrounding normal thyroid tissue by a thin capsule or a clear boundary, giving it a rounded, well-circumscribed appearance.
Follicular growth pattern. The tumor is made up of small round structures called follicles, similar to those found in normal thyroid tissue. True papillae (finger-like projections) should not be present.
Papillary-like nuclear features. The nuclei (the parts of the cells that contain the genetic material) look similar to those seen in papillary thyroid carcinoma. These changes include enlarged, pale or clear-appearing nuclei, irregular nuclear outlines, and nuclei that appear crowded or overlapping.
No invasion. The tumor cells do not grow through the capsule into the surrounding thyroid (no capsular invasion), and they are not found inside blood vessels or lymphatic channels (no vascular or lymphatic invasion).
No aggressive features. There are no areas of tumor cell death (necrosis), no unusually rapid cell division, and no very irregular-looking nuclei.

All of these features must be present for the diagnosis of NIFTP. If any sign of invasion or aggressive growth is found, the tumor is reclassified as a different kind of thyroid tumor — usually follicular variant of papillary thyroid carcinoma or follicular thyroid carcinoma, both of which are cancers.

Biomarkers in NIFTP

Molecular (biomarker) testing is not needed to diagnose NIFTP in most cases — the diagnosis is made based on the appearance of the tumor under the microscope. However, in some cases, molecular testing performed on an FNA sample before surgery, or on the tumor after surgery, can help support the diagnosis.

NIFTP often carries mutations in the RAS family of genes (HRAS, KRAS, or NRAS), which are also seen in benign follicular thyroid tumors. In contrast, genetic changes typical of more aggressive thyroid cancers — such as the BRAF V600E mutation, TERT promoter mutations, or PIK3CA mutations — should not be present in a true NIFTP. When a biomarker typical of aggressive thyroid cancer is found in a tumor that otherwise looks like NIFTP, pathologists review the tumor carefully to make sure a small area of invasion or cancer has not been missed.

Molecular findings alone cannot confirm or rule out the diagnosis of NIFTP. The most important part of the diagnosis remains careful microscopic examination of the whole tumor.

Margins

A margin is the edge of the tissue removed during surgery. The pathologist examines the margins to determine whether any tumor cells extend to the cut edge. When NIFTP is completely removed, margins are usually negative, meaning no tumor cells are seen at the edge. Because NIFTP is not a cancer, margin status is primarily used to confirm complete removal rather than to determine additional treatment.

What happens after the diagnosis?

The outlook for people diagnosed with NIFTP is excellent. When strict diagnostic criteria are met and the tumor has been completely removed, no further treatment is usually needed. In particular:

Radioactive iodine therapy is not required. This is one of the most important practical differences between NIFTP and thyroid cancer.
Thyroid hormone suppression therapy is not needed. Patients who had only part of the thyroid removed (lobectomy) can usually keep their remaining thyroid and do not need to take thyroid hormone medication, unless blood tests later show that thyroid hormone levels have dropped.
Follow-up is usually light. Most patients are followed with periodic clinical examinations, thyroid blood tests, and, if indicated, a neck ultrasound. The intensity of follow-up is much less than would be needed for a thyroid cancer.

In very rare cases, tumor cells have been reported outside the thyroid after a NIFTP diagnosis. When this happens, it usually means that a small area of invasion was missed in the original specimen, and the diagnosis may need to be revised. This is one reason why careful, complete microscopic examination at the time of surgery is so important.

Questions to ask your doctor

Was the tumor completely removed?
Were all the strict criteria for NIFTP met on pathology review?
Was any invasion (capsular, vascular, or lymphatic) found?
Do I need any additional treatment?
Do I need radioactive iodine therapy?
Do I need to take thyroid hormone medication after surgery?
How often should my thyroid be monitored with blood tests or ultrasound?
Should any of my family members be concerned about thyroid disease?