Your pathology report for non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP)

by Jason Wasserman MD PhD FRCPC
February 5, 2026

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a noncancerous thyroid tumour 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.

Although NIFTP cells can look similar under the microscope to cells seen in papillary thyroid carcinoma, this tumour 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 spread or recurrence.

This article explains what NIFTP is, how it is diagnosed, what pathologists look for under the microscope, and why this diagnosis is generally very reassuring.

A note on the name and classification

Before 2016, NIFTP was called non-invasive encapsulated follicular variant of papillary thyroid carcinoma. Although the term “carcinoma” was used, long-term follow-up studies showed that these tumours behaved in a noncancerous manner when 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 tumours behave. Today, NIFTP is recognized as a distinct diagnosis that helps patients avoid unnecessary aggressive treatment.

What are the symptoms of NIFTP?

Most people with NIFTP do not have symptoms. The tumour is often discovered during a routine physical examination as a thyroid nodule or incidentally on imaging studies done for other reasons.

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

What causes NIFTP?

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

NIFTP is not inherited and does not run in families.

How is this diagnosis made?

A diagnosis of NIFTP can only be made after the entire tumour has been surgically removed and carefully examined under the microscope. This is because the diagnosis depends on confirming that the tumour has not invaded surrounding thyroid tissue or blood vessels.

The diagnostic process usually involves imaging, biopsy, surgery, and detailed microscopic examination. Each step provides helpful information, but the final diagnosis is almost always made after surgery.

Imaging

Ultrasound is usually the first imaging test performed. NIFTP typically appears as a well-defined thyroid nodule, often with a smooth outline. However, imaging cannot reliably distinguish NIFTP from other follicular thyroid tumours, including benign adenomas or cancers. Imaging findings alone are therefore not sufficient to make this diagnosis.

Fine-needle aspiration (FNA)

Fine-needle aspiration involves removing a small sample of cells from the thyroid nodule using a thin needle. FNA can identify a follicular-patterned tumour, meaning the cells are arranged in small round structures similar to normal thyroid follicles (the units that store thyroid hormone). However, FNA cannot determine whether the tumour is invasive, which is essential for diagnosing NIFTP.

As a result, FNA reports often use terms such as follicular neoplasm or suspicious for follicular neoplasm, and surgery is required to reach a final diagnosis.

Microscopic examination

Under the microscope, NIFTP is a well-circumscribed tumour that is separated from the surrounding thyroid tissue by a thin capsule or a clear boundary. The tumour is follicular-patterned, meaning it is composed of follicles similar to those found in normal thyroid tissue.

The tumour cells show papillary-like nuclear features, which are changes in the nucleus (the part of the cell that holds genetic material) that resemble those seen in papillary thyroid carcinoma. These include pale or clear-appearing nuclei, nuclear enlargement, irregular nuclear outlines, and overlapping nuclei.

Notably, despite these nuclear changes, the tumour shows no capsular invasion (tumour cells do not grow through the capsule) and no vascular invasion (tumour cells are not found inside blood vessels). There is also no tumour necrosis or aggressive growth pattern. These features are critical for confirming the diagnosis of NIFTP.

Molecular tests

In some cases, molecular testing may be performed as part of the diagnostic workup. NIFTP commonly shows mutations in the RAS family of genes, which are also seen in benign follicular thyroid tumours. In contrast, genetic changes associated with more aggressive thyroid cancers—such as BRAF V600E, TERT promoter, or PIK3CA mutations—should not be present in true NIFTP.

Molecular findings can support the diagnosis, but they do not replace careful microscopic examination, which remains the most critical part of the process.

Lymphatic and vascular invasion

Lymphatic invasion means tumour cells are found inside lymphatic vessels, which carry fluid to lymph nodes. Vascular invasion means tumour cells are found inside blood vessels. Neither lymphatic nor vascular invasion should be present in NIFTP.

If either type of invasion is identified, the diagnosis of NIFTP cannot be made, and the tumour must be reclassified as a different type of thyroid neoplasm.

Margins

A margin is the edge of tissue removed during surgery. When the tumour is completely removed, margins are usually negative, meaning no tumour cells are seen at the cut edge. Because NIFTP is non-invasive, margin status is mainly used to confirm complete removal and does not usually affect further treatment decisions.

What is the prognosis for NIFTP?

The outlook for people diagnosed with NIFTP is excellent. When strict diagnostic criteria are met, and the tumour is completely removed, additional treatments such as radioactive iodine are not required, and recurrence is not expected.

Very rarely, tumour cells may later be found outside the thyroid. In such cases, this usually means that a small focus of invasion was not recognized in the original specimen, and the diagnosis may need to be revised.

Questions to ask your doctor

• Was my tumour completely removed?

• Were all the criteria for NIFTP met on pathology review?

• Do I need any additional treatment, or should I follow up?

• How often should my thyroid be monitored?

• Do I need thyroid hormone replacement after surgery?