Esthesioneuroblastoma

Esthesioneuroblastoma or ENB is a rare cancer that involves the growth of tumors in the nasal cavity. It is also referred to as olfactory neuroblastoma. Little is known about the cause of this condition, and medical professionals are divided on how best to stage the cancer or treat it.

Definition & Facts

Esthesioneuroblastoma is a rare type of cancer of the nasal cavity and surrounding areas. This condition is believed to be caused by neuroepithelium, a specialized type of tissue that contains sensory nerve endings in the olfactory system.

The tumor or tumors can be present in the upper nasal cavity and the front of the skull. This particular type of cancer has a large variation in severity, ranging from inactive and relatively benign to aggressive. ENB is a very rare cancer with fewer than 1,000 cases confirmed since it was first identified in 1924. 

Symptoms & Complaints

The symptoms and complaints related to ENB include both physical and neurological symptoms. Individuals with ENB may complain of olfactory or nasal issues, vision problems, and hearing problems or ear issues. Nasal problems usually present first, and other symptoms may only occur after extended tumor growth. Common symptoms include:

• Nasal obstruction or blockage
• Nasal stuffiness
• Trouble breathing through the nose
• Nosebleeds
• Headaches
• Facial pain
• Facial swelling
• Decreased sense of smell

Additional symptoms include:

• Double vision
• Bulging of the eyes (exophthalmos)
• Vision trouble
• Blindness
• Decreased sense of taste
• Loose teeth
• Mouth ulcers or sores
• Trismus or lockjaw
• Neck swelling
• Changes in mental state
• Nausea and vomiting
• Ear pain
• Otitis media (infection of the middle ear)
• Coma

Depending on the severity of the tumor growth, symptoms may present rapidly or may occur slowly over time. If the cancer begins metastasizing or spreading, it can cause symptoms and complaints in other parts of the body. Neck metastases, especially in the lymph nodes, are observed in a significant number of patients. ENB is capable of metastasis in other, more distant areas of the body as well although that is less common. 

Causes

Exactly what causes ENB is not known. The rarity of the condition limits the amount of research, leaving much about the condition and its origins unknown. It is generally believed that it originates in the olfactory neuroepithelium – the tissues that line the inner portions of the nasal cavity. Other theories on the cell of origin include various clusters of nerve cells (ganglia) in the nose or the olfactory nasal placode cells that create the epithelium tissues.

Additionally, ENB has been linked to smoking and smokers are considered to be at a higher risk of developing the condition. Some links between ENB and trisomy 8 have been observed. Trisomy 8 is a condition where there are three copies of chromosome 8 in the DNA, which has also been linked to chronic myeloid leukemia, a form of leukemia. 

Diagnosis & Tests

Esthesioneuroblastoma can be difficult to diagnose due to its rarity and the similarity of its symptoms to other, less harmful conditions. It is often confused with benign conditions like sinus infections and inflammation or misdiagnosed as other types of neoplasms or tumors in the nasal cavity.

It can take six months to a year from the first time symptoms are reported until an ENB diagnosis has been provided. This can result in patients not being diagnosed until the cancer is in an advanced stage. Many methodologies and tests can be used to diagnose ENB. Some common techniques include:

• Thorough medical history and family history and detailing of symptoms
• Comprehensive head and neck physical examination
• Nasal endoscopy
• biopsy
• Computed tomography (CT) scans 
• Magnetic resonance imaging (MRI)
• Positron emission tomography (PET) scan
• Immunohistochemical staining

Most frequently, an ENB diagnosis will be obtained using a combination of these methods.

If suspected, a biopsy will be obtained, usually during a nasal endoscopy procedure that allows doctors to evaluate the tumor and determine its exact location and size. Once the diagnosis has been confirmed, further testing and imaging will be required to identify potential metastasis and determine where in the body the cancer has spread. This is commonly done by CT scan with contrast dye. A full workup will include head, neck, chest, and abdominal scans. Doctors may also recommend liver function tests. 

Treatment & Therapy

Several opinions regarding treatment of ENB exist. Its rarity and complexity have resulted in a lack of consensus on its underlying causes, the correct staging system to use, and the various therapies used to treat it. Treatment will also vary depending on the stage of the tumor, both nearby and distant metastasis, and the patient's overall health.

Common modalities for treatment include surgery, radiation, and chemotherapy. A combination of these methods will be prescribed for full treatment. In most cases, a team of doctors will be required for treatment, including surgeons, radiation oncologists, medical oncologists, and other specialists. 

Surgery is the most common and widely agreed on treatment for ENB. Traditional, open surgical treatment is invasive and includes incisions that remove the tumor and any involved structures in the nasal cavity. Minimally-invasive endoscopic surgeries have also been used to treat ENB. This surgical method is more appropriate for smaller tumors that have not spread into other tissues.

Although surgery is the most common procedure for ENB, recurrence rates post-surgery remain relatively high. Additionally, as with all surgery, some risk is associated with the procedure. 

With more advanced tumors, additional treatment steps may be taken. Radiation therapy can be used in conjunction with surgical treatments to ensure the successful removal of all cancerous tissue. The most successful treatments to date have included surgical and radiotherapy treatments.

For larger tumors and more complex scenarios, preoperative chemotherapy techniques (neoadjuvant therapy) have been used with some success. This helps to shrink and weaken the tumor before surgically removing it. Postoperative radiotherapy (adjuvant therapy) is also commonly used in these situations. 

Prevention & Prophylaxis