Your pathology report for nasopharyngeal carcinoma

by Jason Wasserman MD PhD FRCPC
November 13, 2025

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Nasopharyngeal carcinoma is a type of cancer that originates in the nasopharynx, the area located at the back of the nose and upper throat. The nasopharynx sits behind the nasal cavity and above the soft palate. Air passes through this space when you breathe through your nose.

Nasopharyngeal carcinoma arises from the cells that line the inner surface of the nasopharynx. Most tumours are a subtype of squamous cell carcinoma, which is a cancer of the squamous cells that form the surface lining. Pathologists divide nasopharyngeal carcinoma into three main types: non-keratinizing, keratinizing, and basaloid.

Most non-keratinizing and basaloid tumours are associated with infection by Epstein–Barr virus (EBV), a common virus that can alter how cells grow. In contrast, keratinizing tumours are usually linked to cigarette smoking and heavy alcohol use.

What are the symptoms of nasopharyngeal carcinoma?

Symptoms depend on the size and location of the tumour and how far it has spread. Some people have few or no symptoms early on. Common symptoms include:

• A lump in the neck caused by an enlarged lymph node.

• Nasal blockage or stuffiness.

• Nosebleeds or blood-tinged mucus.

• Ringing in the ears or hearing loss, often on one side.

• Ear fullness or recurrent ear infections, especially in adults.

• Headache or facial pain.

• Double vision or other eye symptoms may occur if the large nerves near the eye are affected.

Because many other conditions can cause these symptoms, a thorough evaluation by an ear, nose, and throat (ENT) specialist is usually needed.

What causes nasopharyngeal carcinoma?

Nasopharyngeal carcinoma develops when cells in the lining of the nasopharynx acquire genetic changes that allow them to grow uncontrollably. These changes often occur in the setting of Epstein–Barr virus (EBV) infection or exposure to certain environmental factors.

EBV causes most cases of non-keratinizing and basaloid nasopharyngeal carcinoma. The virus infects nasopharyngeal cells, and over time, these infected cells accumulate genetic alterations, eventually becoming cancerous.

The keratinizing type is typically associated with cigarette smoking and excess alcohol consumption, which damage the lining of the nasopharynx and increase cancer risk. Other factors that may play a role include family history, specific dietary exposures (such as preserved foods containing nitrosamines), and genetic susceptibility.

Types of nasopharyngeal carcinoma

The type of nasopharyngeal carcinoma can only be determined after the tumour is examined under a microscope by a pathologist. The three main types are non-keratinizing, keratinizing, and basaloid.

Non-keratinizing type

The non-keratinizing type is the most common form of nasopharyngeal carcinoma. The tumour is made up of large, abnormal cells that often grow in clusters and are frequently surrounded by immune cells called lymphocytes. This creates a pattern sometimes described as lymphoepithelioma.

This type is almost always associated with Epstein–Barr virus. Another name for this type is non-keratinizing squamous cell carcinoma of the nasopharynx.

Keratinizing type

The keratinizing type is less common than the non-keratinizing type. The tumour is made up of large abnormal squamous cells that look pink under the microscope because they contain a protein called keratin. Keratin is usually produced by squamous cells, but in cancer, it tends to be disorganized and excessive.

This type is usually associated with cigarette smoking and heavy alcohol use. Another name for this type is keratinizing squamous cell carcinoma of the nasopharynx.

Basaloid type

The basaloid type is the least common form of nasopharyngeal carcinoma. The tumour is made up of large “blue” cells (because of the way they take up stain) that may form solid nests or complex structures.

Most basaloid tumours are associated with EBV, but some are linked to other risk factors such as smoking. Another name for this type is basaloid squamous cell carcinoma of the nasopharynx.

How is this diagnosis made?

The diagnosis of nasopharyngeal carcinoma is usually made after a biopsy is taken from the tumour and examined by a pathologist.

Clinical examination and imaging

An ENT specialist examines the nasopharynx using a mirror or a flexible camera passed through the nose (nasopharyngoscopy). They look for masses or irregularities and may feel the neck for enlarged lymph nodes.

Imaging studies, such as CT scans, MRI, or PET-CT scans, help determine the size of the tumour, whether it has grown into nearby structures like bone or nerves, and whether it has spread to lymph nodes or distant organs.

Biopsy and microscopic examination

A small piece of tissue is removed from the abnormal area in the nasopharynx during endoscopy. The tissue is then sent to a pathology laboratory where it is processed and examined under the microscope.

On a biopsy, the pathologist can determine the type of nasopharyngeal carcinoma (non-keratinizing, keratinizing, or basaloid) and confirm that the tumour is malignant. The biopsy report describes the cell type and pattern of growth and may mention whether the tumour appears associated with a strong lymphocytic (immune) response.

Surgical removal of the entire tumour is not common as an initial treatment for nasopharyngeal carcinoma, because radiation and chemotherapy are the main treatments. However, if surgery is performed (for example, for recurrence), the resection specimen allows the pathologist to describe tumour size, extension into surrounding structures, margin status, and any additional features not visible on the original biopsy.

Immunohistochemistry

Immunohistochemistry is a test that uses antibodies to detect specific proteins in tumour cells. It can help confirm the diagnosis of nasopharyngeal carcinoma and rule out other tumours that can look similar under the microscope.

In nasopharyngeal carcinoma, tumour cells are usually positive for pan-cytokeratin, which indicates they are epithelial in origin, and for high-molecular-weight keratins such as CK5, which supports squamous differentiation. They are generally negative for keratins such as CK7 and CK20, which helps distinguish them from other types of cancer.

Immunohistochemistry is also used to exclude other tumours, such as lymphoma, which is a cancer of lymphocytes and does not show cytokeratin staining.

EBER and Epstein–Barr virus (EBV)

Cells infected by EBV produce a small RNA molecule called Epstein–Barr virus-encoded small RNA, or EBER. Pathologists use a special test called in situ hybridization (ISH) to detect EBER in tumour cells.

Your report will describe the tumour as EBER positive if this test shows EBER inside the cancer cells and EBER negative if no EBER is seen. Most non-keratinizing and many basaloid nasopharyngeal carcinomas are EBER positive. Keratinizing tumours are less commonly associated with EBV and may be EBER negative.

EBER testing is important because it helps confirm the diagnosis of EBV-associated nasopharyngeal carcinoma and can help distinguish it from other head and neck cancers that are not caused by EBV.

Perineural invasion

Perineural invasion refers to the growth of cancer cells along or around a nerve. Nerves are long, wire-like structures composed of neurons that carry signals, such as pain, temperature, and pressure, between the body and the brain.

When tumour cells spread along nerves, they can travel further from the primary tumour and reach nearby organs or deep spaces at the base of the skull. Perineural invasion increases the risk that the tumour will recur after treatment and is considered an adverse prognostic feature.

Pathologists look for tumour cells surrounding or infiltrating a nerve under the microscope and will report perineural invasion if it is seen.

Lymphovascular invasion

Lymphovascular invasion means cancer cells have entered blood vessels or lymphatic channels near the tumour. Blood vessels carry blood throughout the body, while lymphatic channels carry lymph, a clear fluid that drains into lymph nodes.

When tumour cells are found inside these vessels, it suggests the cancer has a pathway to spread to lymph nodes or distant organs such as the lungs or bones. Lymphovascular invasion is therefore associated with a higher risk of metastasis and is reported by the pathologist when present.

Margins

Margins refer to the edges of tissue removed during surgery. For nasopharyngeal carcinoma, surgery is not typically the first treatment, so margins are usually assessed only if a surgical excision or resection is performed (for example, for recurrent disease or a limited residual tumour).

A margin is considered positive when cancer cells are found at the cut edge of the tissue. This suggests that some tumour may have been left behind. A negative margin means no cancer cells are seen at the edge, indicating that the tumour was likely removed completely. Some reports also provide a measurement of the distance between the tumour and the nearest margin, even when all margins are negative.

Margin status helps determine whether additional treatment, such as radiation or chemotherapy, may be needed.

Lymph nodes

Lymph nodes are small immune organs found throughout the body. They filter lymphatic fluid and trap bacteria, viruses, and cancer cells. Nasopharyngeal carcinoma often spreads to lymph nodes in the neck.

Cancer cells usually travel first to the lymph nodes closest to the tumour. Lymph nodes farther away may become involved as the disease progresses. Because of this, lymph nodes in the neck are often examined by imaging and may be sampled using fine needle aspiration (FNA) or removed during a surgical procedure called a neck dissection.

During a neck dissection, lymph nodes from different levels of the neck (for example, levels 1 through 5) are removed. Nodes on the same side of the tumour are described as ipsilateral, while nodes on the opposite side are defined as contralateral.

The pathologist examines each lymph node under the microscope. A node is described as positive if it contains cancer cells and negative if it does not. If cancer is present, the report may include the size of the largest tumour deposit (sometimes referred to as a “focus” or “deposit”) and whether extranodal extension is observed. Extranodal extension means cancer has broken through the capsule of the lymph node into the surrounding tissue and is considered a high-risk feature.

Lymph node findings are important for two reasons. They are used to determine the pathologic nodal stage (pN), and they help estimate the risk of cancer spreading to other parts of the body. This information guides decisions about additional treatment such as radiation therapy, chemotherapy, or immunotherapy.

Pathologic stage

Pathologic staging describes how far the cancer has spread based on what the pathologist sees under the microscope. For nasopharyngeal carcinoma, staging is based on the TNM system and includes a tumour stage (pT) and a nodal stage (pN).

Tumour stage (pT)

This tumour is given a tumour stage between 1 and 4 based on how far the tumour has spread outside of the nasopharynx.

• T1 – The tumour is only seen in the nasopharynx, or it has only spread to the oropharynx or nasal cavity.

• T2 – The tumour has spread outside of the nasopharynx into the soft tissues or muscles that surround the nasopharynx.

• T3 – The tumour has spread into the bones of the skull, the sinuses, or the bones of the spine.

• T4 – The tumour has spread to the eyes, the large nerves of the head (cranial nerves), the parotid gland, or beyond the skull into the cranial cavity (the space that holds the brain).

Nodal stage (pN)

The nodal stage (pN) is based on the number of lymph nodes that contain tumour cells, the size of the largest tumour deposit, and the location of the involved lymph nodes. The stage ranges from N0 to N3.

• N0 – No tumour cells are found in any of the lymph nodes examined.

• N1 – Tumour cells are found in one or more lymph nodes, but the size of each tumour deposit is not larger than 6 centimetres.

• N2 – Tumour cells are found in lymph nodes on both sides of the neck (bilateral lymph nodes), and the size of each tumour deposit is not larger than 6 centimetres.

• N3 – Tumour cells are found in a lymph node, and the size of the tumour deposit is larger than 6 centimetres.

Together, the pT and pN stages help determine the overall stage of disease, which is used to plan treatment and estimate prognosis.

What happens after the diagnosis?

After a diagnosis of nasopharyngeal carcinoma is made, your healthcare team will review your pathology report, imaging results, and overall health to create a treatment plan. The team usually includes an ENT surgeon, medical oncologist, radiation oncologist, and pathologist.

For most patients, the primary treatment is radiation therapy, often combined with chemotherapy. This is because the nasopharynx is challenging to access surgically and because nasopharyngeal carcinomas, particularly EBV-associated non-keratinizing tumours, respond well to radiation and chemotherapy.

Surgery may be considered for persistent or recurrent disease in the nasopharynx or neck after initial treatment. Immunotherapy may be an option for patients with advanced, recurrent, or metastatic disease, particularly when other treatments have become ineffective.

You will be monitored with regular follow-up visits, endoscopic examinations of the nasopharynx, and imaging studies to check for response to treatment and detect any recurrence. Your team may also consider blood tests that measure EBV DNA levels as part of follow-up in EBV-positive cases. Managing side effects such as dry mouth, difficulty swallowing, and hearing changes is an important part of long-term care.

Questions for your doctor

• What type of nasopharyngeal carcinoma do I have (non-keratinizing, keratinizing, or basaloid), and is it associated with EBV?

• Was my tumour tested for EBER, and what were the results?

• How advanced is my cancer, and what are my tumour (pT) and nodal (pN) stages?

• Were lymph nodes involved, and was extranodal extension seen?

• What treatments do you recommend (radiation, chemotherapy, surgery, immunotherapy), and in what order will they be given?

• How will treatment affect my breathing, swallowing, hearing, and quality of life?

• How will my response to treatment be monitored, and how often will I need follow-up visits and scans?

• Are there clinical trials or newer treatments available that might be appropriate for me?