Nasopharyngeal Carcinoma: Understanding Your Pathology Report

by Jason Wasserman MD PhD FRCPC
April 10, 2026

Nasopharyngeal carcinoma is a type of cancer that originates in the nasopharynx — the area at the back of the nasal cavity, above the soft palate and behind the nose. It is one of the most common head and neck cancers in parts of East and Southeast Asia, North Africa, and among certain Indigenous populations, though it can occur worldwide. Most nasopharyngeal carcinomas arise from the squamous cells that line the inner surface of the nasopharynx and are classified into three main microscopic types: non-keratinizing, keratinizing, and basaloid. The two EBV-associated types — non-keratinizing and basaloid — respond particularly well to radiation and chemotherapy and carry a more favorable prognosis than the keratinizing type.

This article will help you understand the findings in your pathology report — what each term means and why it matters for your care.

What causes nasopharyngeal carcinoma?

The causes of nasopharyngeal carcinoma differ by tumor type:

• Non-keratinizing and basaloid types — These are almost always caused by persistent infection with Epstein–Barr virus (EBV), a common herpesvirus spread primarily through saliva. EBV infects cells in the nasopharynx and, over time, causes genetic changes that lead to cancer. Most people infected with EBV never develop cancer — additional genetic and environmental factors are required. Risk factors include certain HLA gene variants, a diet high in salt-preserved foods containing nitrosamines, a family history of nasopharyngeal carcinoma, and residence in or ancestry from endemic regions.
• Keratinizing type — This type is usually not EBV-associated and shares risk factors with other head and neck squamous cell carcinomas: cigarette smoking and heavy alcohol use are the main drivers. It is more likely to occur in Western populations and carries a worse prognosis than EBV-associated types.

What are the symptoms?

Symptoms depend on the size and location of the tumor and whether it has spread. Some people have few or no symptoms in the early stages. Common symptoms include:

• A painless lump in the neck from an enlarged lymph node — often the first sign.
• Nasal blockage or stuffiness, usually on one side.
• Nosebleeds or blood-tinged mucus.
• Ringing in the ears (tinnitus) or hearing loss, typically on one side.
• Ear fullness or recurrent ear infections.
• Headache or facial pain.
• Double vision or other eye changes, if large nerves near the skull base are affected.

Because these symptoms overlap with many benign conditions, a thorough evaluation by an ear, nose, and throat (ENT) specialist is usually needed to identify the cause.

How is the diagnosis made?

The diagnosis is made after a tissue sample is examined under the microscope by a pathologist. The sample is obtained by biopsy during nasopharyngoscopy — an examination in which a flexible camera is passed through the nose to visualize the nasopharynx — from any visible mass or abnormal area. If the first sign of disease is an enlarged lymph node in the neck, a fine-needle aspiration (FNA) of the lymph node may be performed first, followed by a nasopharyngeal biopsy to confirm the primary site.

Under the microscope, the pathologist identifies the type of nasopharyngeal carcinoma (non-keratinizing, keratinizing, or basaloid), confirms that it is malignant, and may note the characteristic dense lymphocytic inflammatory infiltrate often seen in EBV-associated tumors. Special tests — immunohistochemistry and EBER in situ hybridization — confirm the diagnosis and EBV status. Once cancer is confirmed, imaging studies (CT, MRI, and often PET-CT) determine the full extent of the tumor, skull base involvement, and lymph node status.

Surgical removal of the entire nasopharyngeal tumor is not typically performed as initial treatment because radiation and chemotherapy are the primary therapies. If surgery is performed for recurrent or residual disease, the resection specimen allows the pathologist to report tumor size, extension into surrounding structures, and margin status.

Types of nasopharyngeal carcinoma

The histologic type describes how the cancer cells appear under the microscope. Your report will state which type was identified.

• Non-keratinizing type — The most common form. Tumor cells grow in clusters or sheets and appear blue-purple because they produce little or no keratin. The tumor is almost always surrounded by a dense infiltrate of immune cells (lymphocytes), creating a pattern sometimes called lymphoepithelioma. This type is almost always EBV-associated and responds very well to radiation and chemotherapy.
• Keratinizing type — Less common. Tumor cells appear pink under the microscope because they produce keratin. This type is usually not EBV-associated and is more often linked to tobacco and alcohol use. It tends to behave more aggressively and has a worse prognosis than the non-keratinizing type.
• Basaloid type — The rarest form. Tumor cells are small and blue, growing in solid nests. Most basaloid nasopharyngeal carcinomas are EBV-associated and behave similarly to the non-keratinizing type.

EBV and EBER testing

Confirming whether the tumor is associated with Epstein–Barr virus (EBV) is an essential part of evaluating nasopharyngeal carcinoma. EBV status affects prognosis, guides blood-based monitoring during follow-up, and helps distinguish nasopharyngeal carcinoma from other tumors that can look similar under the microscope.

The standard test is EBER in situ hybridization (ISH). EBER (Epstein–Barr virus-encoded small RNA) is a small RNA molecule produced in abundance by EBV-infected cells. The ISH test uses labeled probes that bind to EBER inside the tumor cells, making EBV-infected cells visible under the microscope. Your report will describe the result as:

• EBER positive — EBV RNA is detected inside the cancer cells. Most non-keratinizing and basaloid nasopharyngeal carcinomas are EBER positive. This confirms EBV association and supports the diagnosis.
• EBER negative — No EBV RNA detected. Keratinizing tumors are often EBER negative. A negative result does not exclude nasopharyngeal carcinoma but raises the possibility of a different tumor type or an EBV-independent cancer.

Immunohistochemistry (IHC) is also performed to confirm that the cancer cells are epithelial in origin. Tumor cells in nasopharyngeal carcinoma are typically positive for pan-cytokeratin (confirming epithelial origin) and for high-molecular-weight keratins such as CK5. They are generally negative for CK7 and CK20. This IHC pattern helps distinguish nasopharyngeal carcinoma from lymphoma (a cancer of immune cells that also commonly involves the nasopharynx) and from other carcinoma types.

Perineural invasion

Perineural invasion means cancer cells are growing along or around a nerve. In the nasopharynx, nerves run through the tissue and connect to major cranial nerves at the skull base. When tumor cells travel along nerve pathways, the risk of local spread to the skull base and intracranial extension increases. Perineural invasion is considered an adverse feature and may influence the radiation field used. Your report will state whether it is present or absent.

Lymphovascular invasion

Lymphovascular invasion means cancer cells have entered lymphatic channels or blood vessels near the tumor. These provide a route for spread to lymph nodes or distant organs such as the lungs, liver, or bones. Your report will state whether lymphovascular invasion is present or absent. When found, it is considered an adverse feature that may affect treatment planning.

Surgical margins

Because surgery is not the standard initial treatment for nasopharyngeal carcinoma, margins are typically assessed only when surgery is performed for recurrent or residual disease after radiation. The pathologist examines the cut surfaces of the specimen to determine whether cancer cells are present at the edge.

• Negative margin — No cancer cells at the cut edge. Suggests the tumor was completely removed.
• Positive margin — Cancer cells are present at the cut edge. Suggests some tumor may remain; additional treatment is usually recommended.

Lymph nodes

Lymph nodes in the neck are a common site of spread for nasopharyngeal carcinoma — lymph node involvement is present in most patients at diagnosis. The nasopharynx drains to the retropharyngeal lymph nodes and the upper deep cervical nodes (particularly levels II–V), often on both sides of the neck. A neck dissection may be performed to remove residual or recurrent nodal disease after radiation.

Your pathology report will include the total number of lymph nodes examined, the number containing cancer, the size of the largest tumor deposit, and whether extranodal extension is present — meaning cancer cells have broken through the outer capsule of a lymph node into surrounding tissue. Extranodal extension is a high-risk feature associated with a higher risk of recurrence. Nodes on the same side as the primary tumor are described as ipsilateral; those on the opposite side are contralateral. Bilateral lymph node involvement is common in nasopharyngeal carcinoma and affects the nodal stage.

PD-L1

PD-L1 is a protein that some cancer cells produce to shield themselves from immune attack. Immunotherapy drugs called checkpoint inhibitors — including pembrolizumab (Keytruda) and camrelizumab — work by blocking this mechanism, allowing the immune system to recognize and attack the cancer. PD-L1 testing may be performed for patients with recurrent or metastatic nasopharyngeal carcinoma who are being considered for immunotherapy. Results are reported as a Combined Positive Score (CPS), with a higher CPS generally associated with a greater likelihood of benefit from checkpoint inhibitors.

Pathologic stage (pTNM)

The pathologic stage describes how far the cancer has spread, using the TNM staging system. For nasopharyngeal carcinoma, the T stage is based on how far the tumor has grown into adjacent structures rather than tumor size alone, because even small tumors can spread to critical structures at the skull base.

Tumor stage (pT)

• pT1 — Tumor confined to the nasopharynx, or with extension to the oropharynx and/or nasal cavity, without parapharyngeal involvement.
• pT2 — Tumor with extension into the parapharyngeal space and/or adjacent soft tissue involvement (medial pterygoid, lateral pterygoid, or prevertebral muscles).
• pT3 — Tumor invades the bony structures at the skull base, cervical vertebrae, pterygoid structures, or paranasal sinuses.
• pT4 — Tumor with intracranial extension, involvement of cranial nerves, the hypopharynx, orbit, or parotid gland, or extensive soft tissue infiltration beyond the lateral surface of the lateral pterygoid muscle.

Nodal stage (pN)

• pN0 — No cancer in any lymph nodes examined.
• pN1 — Cancer in lymph nodes in the neck, all 60 mm or smaller — on the same side as the tumor only, unilateral retropharyngeal nodes, or bilateral nodes above the caudal border of the cricoid cartilage.
• pN2 — Cancer in bilateral lymph nodes, 60 mm or smaller, below the caudal border of the cricoid cartilage.
• pN3 — Cancer in any lymph node larger than 60 mm, or any node with extension to the supraclavicular fossa.

What is the prognosis for nasopharyngeal carcinoma?

The prognosis for nasopharyngeal carcinoma is strongly influenced by the tumor type and EBV status, the stage at diagnosis, and the response to treatment.

EBV-associated (non-keratinizing and basaloid) nasopharyngeal carcinoma responds remarkably well to radiation and chemotherapy. Even patients with locally advanced disease and multiple involved lymph nodes frequently achieve long-term remission. Five-year survival rates for non-metastatic EBV-associated disease are typically 60–80% or higher, and outcomes continue to improve with modern treatment protocols. The lymphocyte-rich immune environment of these tumors — reflected in the “lymphoepithelioma” appearance — likely contributes to their sensitivity to treatment.

Keratinizing nasopharyngeal carcinoma behaves more like other tobacco- and alcohol-related head and neck squamous cell carcinomas, with a lower response to treatment and a worse prognosis stage-for-stage compared to EBV-associated types.

An important tool in monitoring EBV-associated nasopharyngeal carcinoma is measurement of EBV DNA levels in the blood (plasma EBV DNA). EBV DNA is released into the bloodstream by tumor cells, and levels rise and fall with disease activity. A detectable or rising EBV DNA level after treatment can signal residual disease or recurrence, sometimes before it is visible on imaging. This blood test has become a standard part of follow-up surveillance for EBER-positive patients.

Adverse pathologic features — perineural invasion, lymphovascular invasion, extranodal extension, and higher T and N stages — are associated with a greater risk of recurrence and worse long-term outcomes.

What happens after the diagnosis?

After diagnosis, your healthcare team — typically an ENT surgeon, radiation oncologist, medical oncologist, and pathologist — reviews your pathology report, imaging, and overall health to create a treatment plan.

For most patients, the primary treatment is radiation therapy to the nasopharynx and neck, usually combined with concurrent chemotherapy (most commonly cisplatin-based). EBV-associated non-keratinizing carcinomas are highly radiosensitive, which is why radiation is so effective and surgery is rarely needed as initial treatment. Chemotherapy given before radiation (induction chemotherapy) may be added for more advanced disease to reduce the tumor burden before the main radiation course.

Surgery may be considered for residual disease in the nasopharynx or neck lymph nodes after radiation has been completed. For recurrent or metastatic disease, systemic options include platinum-based chemotherapy, immunotherapy (particularly for PD-L1-expressing tumors), and newer targeted agents being evaluated in clinical trials.

After treatment, follow-up includes regular ENT examinations, imaging studies, and for EBER-positive patients, periodic plasma EBV DNA measurements. Managing long-term effects of radiation — including dry mouth, difficulty swallowing, hearing changes, and dental problems — is an important part of ongoing care.

Questions to ask your doctor

• What type of nasopharyngeal carcinoma do I have — non-keratinizing, keratinizing, or basaloid?
• Was EBER testing performed, and is my tumor EBV-associated?
• What is my pathologic stage — both the tumor stage (pT) and nodal stage (pN)?
• Did the tumor extend into the skull base, cranial nerves, or other adjacent structures?
• Were lymph nodes involved, and on which side of the neck? Was extranodal extension present?
• Was perineural invasion or lymphovascular invasion found?
• If surgery was performed, were the margins negative?
• Was PD-L1 testing done, and could I benefit from immunotherapy?
• What treatment plan do you recommend — radiation, chemotherapy, or a combination?
• Will my EBV DNA levels be monitored in the blood, and how will this guide follow-up?
• How will side effects such as dry mouth, hearing changes, and difficulty swallowing be managed?
• Are there clinical trials available for my type and stage of nasopharyngeal carcinoma?
• How often will I need follow-up imaging and examinations?