The nasal cavity

The nose opens into the nasal passageway, or cavity. This cavity runs along the top of the palate (the roof of the mouth, the shelf that separates your nose from your mouth) and turns downward to join the passage from the mouth to the throat.

The paranasal sinuses

The term paranasal means "around or near the nose." Sinuses are cavities or small tunnels. The nasal cavity and paranasal sinuses help filter, warm, and humidify the air you breathe. They also give your voice resonance, lighten the weight of the skull, and provide a bony framework for the face and eyes.

The nasal cavity opens into a network of paired sinuses:

• Maxillary sinuses are in the cheek area, below the eyes, and on either side of the nose.
• Frontal sinuses are above the inner eye and eyebrow area.
• Sphenoid sinuses are situated deep behind the nose, between the eyes.
• Ethmoid sinuses are made up of multiple, sieve-like sinuses formed of thin bone and mucous tissues. They are located above the nose, between the eyes.

Normally, these sinuses are filled with air. When you have a cold or sinus infection they can fill with mucus and pus, often becoming obstructed, and cause discomfort.

The nasal cavity and the paranasal sinuses are lined by a layer of mucous producing tissue called mucosa. The mucosa has multiple types of cells including:

• squamous epithelial cells, which are lining cells and form the majority of the mucosa
• glandular cells such as minor salivary gland cells, which produce mucus and other fluids
• nerve cells which are responsible for sensation and the sense of smell in the nose
• infection-fighting cells (which are part of the immune system), blood vessel cells, and other supporting cells

All of the cells that make up the mucosa can become cancerous and each type behaves or grows differently. The types of tumors formed when these cell types become cancerous include:

• Squamous epithelial cells can become squamous cell carcinoma. This is the most common type of cancer in the nasal cavity and paranasal sinuses. It makes up a little over half of cancers of these areas.
• Gland cells can turn into adenocarcinomas and mucoepidermoid cancers. These are the next most frequent type of nasal and paranasal sinus cancers, making up about 10% to 20% of cancers in these areas.
• A type of cancer that can also come from mucosa cells is called undifferentiated carcinoma. It makes up about 7% of cancer in the nasal cavity and paranasal sinuses.
• Cells that give the skin color are called melanocytes. These cells give rise to a type of cancer called malignant melanoma. This is an aggressive cancer that comprises about 7% of the nasal and paranasal sinus tumors.
• A cancer that starts in the nerve for the sense of smell (the olfactory nerve) is called esthesioneuroblastoma. This tumor is also known as olfactory neuroblastoma. This type of cancer usually occurs on the roof of the nasal cavity and involves a structure called the cribiform plate. The cribiform plate is a bone deep in the skull, between the eyes, and above the ethmoid sinuses. These tumors make up about 7% of the cancers of the nasal cavity and paranasal sinuses. They can sometimes be mistaken for other types of tumors, like undifferentiated carcinoma (a rapidly growing cancer) or lymphoma.
• Malignant lymphomas (cancer arising from immune system cells called lymphocytes) can also occur in the nasal cavity and paranasal sinuses. One type of lymphoma seen in this area, T-cell/natural killer cell nasal-type lymphoma, was previously called lethal midline granuloma. Information about the diagnosis and treatment of lymphomas can be found in the American Cancer Society document, Non-Hodgkin Lymphoma.
• Cancers of muscle, bone, cartilage, and fibrous cells may also occur. These are sarcomas, and make up about 6% of nasal and paranasal sinus cancers.
• Papillomas also occur in the nasal cavity and paranasal sinuses. They are growths similar to warts that can destroy healthy tissue. Papillomas are not cancer, but sometimes a squamous cell carcinoma will start in a papilloma. Inverting papilloma is a type of papilloma that is officially a benign tumor, but tends to act more like a cancer. It has a tendency to recur (come back) and can grow into surrounding tissues. The treatment of inverting papilloma often includes the same type of surgery that is used for cancer.