Non-keratinizing squamous cell carcinoma of the nasopharynx

By Jason Wasserman MD PhD FRCPC
October 1, 2024

Non-keratinizing squamous cell carcinoma (also known as non-keratinizing nasopharyngeal carcinoma) is the most common type of nasopharyngeal cancer. It starts in the nasopharynx, the upper part of the throat located behind the nose. The tumour arises from the squamous cells that line the surface of the nasopharynx.

What are the symptoms of non-keratinizing squamous cell carcinoma?

Patients with this type of cancer often experience symptoms such as nasal congestion, nosebleeds, or a lump in the neck due to enlarged lymph nodes. Other symptoms may include ear pain or hearing loss, headaches, and difficulties with swallowing or speaking. Some individuals may also experience facial numbness or vision changes if the cancer affects nearby nerves.

What causes non-keratinizing squamous cell carcinoma of the nasopharynx?

The exact cause of this cancer is not entirely understood, but certain factors increase the risk of developing it. One of the most significant risk factors is the Epstein-Barr Virus (EBV) infection. Other potential risk factors include a family history of nasopharyngeal carcinoma, smoking, and exposure to certain chemicals or dust. Genetic predisposition and dietary habits, such as consuming preserved foods high in salt, may also play a role.

How is this diagnosis made?

Diagnosing non-keratinizing squamous cell carcinoma of the nasopharynx usually involves a combination of physical examination, imaging tests, and biopsy. During a physical examination, the doctor will look for lumps in the neck and changes in the nasopharynx. Imaging studies, like magnetic resonance imaging (MRI) or computed tomography (CT) scans, help assess the size and extent of the tumour. A biopsy involves taking a tissue sample from the tumour and examining it under a microscope to confirm the diagnosis by a pathologist. This is often performed using a procedure called nasopharyngoscopy, where a flexible tube with a camera is inserted through the nose to view the nasopharynx.

Microscopic features of this tumour

When viewed under the microscope, non-keratinizing squamous cell carcinoma of the nasopharynx appears as clusters of large cells with oval or round nuclei and indistinct cell borders. These cells often form sheets or islands within the tissue. Unlike keratinizing forms, there is an absence of keratin pearls, which are round clusters of cells producing the protein keratin. There may also be areas of necrosis (cell death) and an inflammatory response around the tumour.

Immunohistochemistry

Immunohistochemistry (IHC) is a technique used to identify specific proteins within the tumour cells, helping to confirm the diagnosis. In non-keratinizing squamous cell carcinoma of the nasopharynx, the tumour cells typically test positive for markers such as cytokeratins (like CK5/6) and p63, proteins found in squamous cells.

Testing for Epstein-Barr virus

To detect the presence of Epstein-Barr Virus (EBV) in the tumour, pathologists use a test called Epstein-Barr virus-encoded RNA (EBER) in situ hybridization. This test identifies EBV genetic material within the tumour cells. The detection of EBER is an important feature that helps distinguish non-keratinizing squamous cell carcinoma of the nasopharynx from other head and neck cancers. EBV testing can also be performed through blood tests that look for EBV DNA or antibodies, but the tissue-based EBER test is more specific for diagnosing this type of cancer.

What is the prognosis for a person diagnosed with non-keratinizing squamous cell carcinoma of the nasopharynx?

The prognosis for individuals diagnosed with non-keratinizing squamous cell carcinoma of the nasopharynx depends on various factors, including the stage of the tumour at diagnosis, the patient’s overall health, and the presence of EBV. Generally, early-stage cancers have a better prognosis than more advanced ones. Non-keratinizing squamous cell carcinoma, particularly when associated with EBV, tends to respond well to treatment with radiation therapy and chemotherapy. Regular follow-up care is essential to monitor for recurrence or any treatment-related side effects.