What is Ameloblastoma?
Ameloblastoma is a term that combines the early English word “amel,” which means enamel, and the Greek word “blastos,” which means germ. These tumors are uncommon and are associated with tooth development (odontogenic). They originate from cells located around the root of the tooth or nearby areas. These original cells come from a layer of cells present during our early development (the ectodermal germ layer). Although they only represent about 1% of all jaw tumors, they are the second most common tumor associated with tooth development. They are more often found in the lower jaw than the upper jaw, and are especially common towards the back of the lower jaw. These tumors are usually not cancerous but can behave aggressively. It is quite rare, but they can sometimes become cancerous or be linked to a cancerous tumor (malignant ameloblastoma or ameloblastic carcinoma). Because they are associated with teeth and their structures, it is exceptional to find these tumors outside of the upper and lower jaws.
Regarding teeth anatomy, there are 20 baby teeth and 32 adult teeth, although the exact number can depend on the development of the wisdom teeth. These start to appear in the mouth when a person is around 6 years old. The last four teeth to come through are the wisdom teeth, and they may or may not appear. In children, there are usually ten teeth found in the upper jaw and ten in the lower jaw. For adults, 16 teeth are in the upper jaw, and 16 are in the lower jaw.
Each type of tooth has unique landmarks that determine whether they are incisors, molars, canines, and so on. The tooth includes the root, which is hidden in the gums, and the crown, which is the visible part. The root helps hold the tooth in place and allows for blood flow and nerve connections to keep the tooth alive. There is a system of ligaments (called the periodontium) that help keep everything connected. The hard part of the tooth you see is covered by enamel, and the root is covered by cementum, a mineral substance not as hard as enamel.
Most ameloblastomas are benign (not cancerous) and grow slowly, but they can behave aggressively. Their abnormal cell growth can spread into the local area, commonly the bone. This often results in surgical treatment. Even with successful surgery, these tumors have a high chance of coming back, therefore needing ongoing checks for the rest of a person’s life.
Ameloblastomas spread locally, which means they invade surrounding tissues. They can spread through bone and, if given enough time, can spread into soft tissues. Very rarely, this benign tumor can spread to lymph nodes and more distant sites, becoming cancerous in less than 1% of all ameloblastomas, as current understandings suggest.
What Causes Ameloblastoma?
Ameloblasts, which originate from the skin-like tissue, or ectoderm, help form our teeth. These cells have an important role in tooth development because they create tooth enamel. The enamel is the outer surface of the top part of our teeth. Interestingly, ameloblasts only become active after another type of cells called odontoblasts create the first layer of dentin, which is found beneath the enamel. After they’ve done their job, ameloblasts then join the enamel layer and eventually die off, either before or after the tooth emerges.
You can find remnants of these cells in structures in and around the tooth. These leftovers are known as cell rests of Malessez and cell rests of Serres. Today, we think that tumors called ameloblastomas can come from either these leftover cells or other skin-like cells associated with the enamel organ, which is basically the factory for tooth enamel.
Mostly, about 80% of these tumors happen in the lower jaw, while the other 20% occur in the upper jaw.
Risk Factors and Frequency for Ameloblastoma
Ameloblastomas are medical conditions that can affect people of various ages, but they are most common in individuals between 20 and 40 years old. It’s rare to see ameloblastomas in children under ten, and both men and women are affected equally by the condition. Most of the time, these tumors occur in the lower jaw, but they can also appear in the upper jaw.
A research study conducted by Rizzitelli A and team looked at 293 patients with malignant ameloblastoma across the United States and found that the overall rate of new cases was 1.79 per 10 million people every year. Their research also showed that this condition is more common in men than women and in Black individuals than White individuals. Furthermore, malignant ameloblastomas make up 1.6 to 2.2% of all odontogenic (tooth-related) tumors. The rate at which men are affected compared to women ranges from 2.3 to 5 according to previous studies.
There are different versions of ameloblastoma which are more likely to appear in specific populations. The ameloblastic fibroma is one variation that typically shows up in individuals aged 10 to 16. Its treatment involves simple removal and scraping out (enucleation and curettage). The ameloblastic fibro-odontoma is another variant that usually occurs in individuals aged 6 to 10. Treatment for this also involves enucleation and curettage. Demographic info and radiographs (X-rays) are crucial in accurately diagnosing these conditions.
Malignant ameloblastoma, a more severe form of the condition, can occur in individuals from their teenage years through old age.
Signs and Symptoms of Ameloblastoma
Ameloblastomas, a type of tumor that usually doesn’t cause symptoms until the patient notices a swelling inside their mouth or on their face. This often results in a gradual expansion of the upper (maxillary) or lower (mandibular) jawbone, causing the face to become uneven. Apart from these, experiencing pain or altered sensation is rare. However, patients may report a change in the way their teeth fit together when they bite down, or they might notice loose teeth. Smaller tumors are typically first spotted during regular dental x-rays. If these tumors are not treated, they can grow very large and cause significant changes to the face. This is particularly common in less developed countries where individuals may not have quick access to medical care or may delay seeking help.
- Swelling inside the mouth or on the face
- Expansion of the upper or lower jawbone
- Uneven face
- Change in bite
- Loose teeth
Testing for Ameloblastoma
Doctors use your medical history, a physical exam, and imaging—usually a CT scan—to assess tumors and their characteristics. On a CT scan, ameloblastomas (specific types of tumors) show up as dark spots on either your upper (maxilla) or lower (mandible) jawbone. They often look like bubbles trapped in soap or cause bones to expand or teeth roots to dissolve. They’re also often found with teeth that haven’t come out yet. But to be certain it’s an ameloblastoma, a surgical biopsy is necessary, which involves taking a small tissue sample that is examined under a microscope.
Because it’s crucial to tell it apart from another type of cancer (primary intraosseous squamous cell carcinoma), the CT scan plays a significant role.
There are two main types of harmful (or malignant) ameloblastomas according to the World Health Organization (WHO):
1. Metastasizing ameloblastoma: This looks and behaves the same as a harmless (or benign) ameloblastoma under the microscope, but it spreads to other parts of the body.
2. Ameloblastic carcinoma: This one shows signs of being harmful under the microscope. It comes in two flavors:
* Primary ameloblastic carcinoma: This starts independently or “anew,” as the Latin phrase de novo translates.
* Secondary ameloblastic carcinoma: This starts as a benign ameloblastoma but changes into something risky over time.
Treatment Options for Ameloblastoma
Ameloblastomas are a type of tumor that often affects the jaw. If you have a solid or mural ameloblastoma, which are types of this tumor, it is typically treated with surgery that removes the whole tumor along with a small portion of normal bone around it. This margin can be around five to fifteen millimeters, but most frequently, ten millimeters of normal bone are removed around the tumor. Despite this treatment, these tumors can come back in up to 70% of cases. This high recurrence rate is usually due to the tumor not being fully removed during the first surgery. Various methods such as enucleation (removing the tumor while preserving as much of the surrounding area as possible), curettage (scraping the tumor away), cryotherapy (freezing the tumor), and marsupialization (making a permanent opening in the tumor to let it drain) have been used to treat ameloblastomas. But these are not proven to fully remove the tumor and currently are not considered the standard of care.
If the tumor is an ameloblastic carcinoma, a more aggressive form of ameloblastoma, it’s common to remove it surgically with margins that are two to three centimeters. If the surgery doesn’t fully remove the carcinoma or if it encases a nerve, additional treatment with chemotherapy and radiation may be needed after surgery. Alternatively, malignant ameloblastoma, a type of tumor that spreads to other body parts, is usually treated with surgery and removal of one to two centimeters of normal tissue around the tumor. As it’s often slow-growing, aggressive treatments like chemotherapy or radiation are typically not required.
No matter the type of treatment you receive, it’s important to have regular check-ups to see if the tumor comes back. Experts recommend that you have these for at least five years after your treatment. Doctors use the most up-to-date guidelines from the American Joint Committee on Cancer and the National Comprehensive Cancer Network, known as NCCN, to decide what the best treatment plan is and whether to use other treatments such as neck dissections, chemotherapy, or radiation.
What else can Ameloblastoma be?
Identifying the difference between a harmless ameloblastoma (a type of dental tumor) and a malignant, or cancerous, ameloblastoma can be tricky. Both types can appear similar under a microscope, but the malignant ameloblastoma can invade surrounding tissues or spread to other places in the body, while the harmless one does not. It’s important to note that cancerous ameloblastomas are extremely rare, with only about 30 documented cases. There have been several hundred cases of a related condition, ameloblastic carcinoma.
An ameloblastic fibroma is another type of dental tumor that can appear similar to an ameloblastoma under a microscope. It is characterized by small bundles and clusters of cells, a thick layer of collagen, and can sometimes include tooth tissue. The primary distinction from an ameloblastoma is that the fibroma is more primitive and it should not spread to other parts of the body.
Lung cancer, specifically primary squamous cell carcinoma, and other cancers that have spread to the lung can show signs of being cancerous under a microscope. However, they do not display the specific characteristics associated with an ameloblastoma.
Surgical Treatment of Ameloblastoma
Doctors adhere to the most recent advice from major medical organizations, such as the American Joint Committee on Cancer and the National Comprehensive Cancer Network. These organizations provide detailed information on the latest treatment methods, when certain surgeries are necessary, and the use of chemotherapy and radiotherapy for treating cancer. It’s worth noting that these guidelines are updated every year to include the latest research and medical advances.
What to expect with Ameloblastoma
Malignant ameloblastoma, a type of cancer, is very rare, so it’s hard to determine how it may progress or how well someone with this condition could recover. This type of cancer grows slowly, which means that it might not even be noticeable until up to 10 years after the removal of a benign (non-cancerous) ameloblastoma.
Possible Complications When Diagnosed with Ameloblastoma
The problems associated with malignant ameloblastoma often stem from its ability to invade nearby areas or spread to different parts of the body. Local complications might include progressive distortion of the upper and lower jaw, which can lead to physical deformity, pain, and misalignment of the teeth.
Complications of malignant ameloblastoma:
- Invasion of nearby areas
- Spread to different parts of the body
- Distortion of the upper and lower jaw
- Physical deformity
- Pain
- Misalignment of the teeth
Preventing Ameloblastoma
It’s important that patients understand that ameloblastomas, a type of oral tumor, are typically harmless, but they have a high chance of coming back. This is why it’s vital for patients to regularly check-in with their doctor, so that any returning or possibly cancerous ameloblastomas can be spotted and treated. This is especially crucial as it’s hard to tell benign (harmless) and malignant (cancerous) ameloblastomas apart just by looking at their cellular structures.
