What Is Adamantinoma?
An adamantinoma is a rare low-grade malignant (cancerous) bone tumor of unknown etiology. It most commonly occurs in the tibia of adolescents and young adults after the bones stop growing. The tibia, also known as the shinbone, is one of two bones that form the leg. These tumors are locally aggressive and can potentially metastasize (spread to other sites in the body), most often the lungs, lymph nodes, and other bones. Reports of metastasis have occurred years after the first diagnosis and following treatment.
What Causes Adamantinoma?
The exact cause of adamantinoma is unknown, but it is thought to develop from certain types of bone cells called osteoblasts. These cells are responsible for building and repairing bone tissue. It is believed that changes or mutations in the DNA of these cells may lead to the development of adamantinoma. However, the specific factors that cause these changes to occur are not yet fully understood. Some studies have suggested that certain genetic factors may increase the risk of developing adamantinoma, but further research is needed to confirm these findings. Other potential risk factors for adamantinoma may include exposure to radiation or certain chemicals, as well as previous injury or trauma to the affected bone.
How Common Is Adamantinoma?
Adamantinoma is a rare tumor representing approximately 0.4 percent of all malignant bone tumors. Adamantinomas mainly affect adolescents and young adults. The tumor is more common in men than women, with a men-to-women ratio of 5:4. The children and elderly populations are rarely affected. The mortality rate associated with adamantinomas is 6 to 18 percent.
What Are the Symptoms of Adamantinoma?
In most cases of adamantinoma, people usually do not have symptoms, and the tumor is discovered in an X-ray obtained for other reasons. However, when symptoms do appear, they tend to vary among people. The most common symptoms include:
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Slow-growing swelling over the tumor site with or without pain.
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Pain in the area of the tumor.
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A fracture due to the tumor weakening the bone.
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The lower leg may have a deformed appearance due to the curving (bowing) of the bone.
How Is Adamantinoma Diagnosed?
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Medical History and Physical Examination: In addition to a physical examination, the healthcare provider doctor reviews the general health and symptoms to get a detailed history of the problem. During the physical examination, the provider looks for swelling, tenderness over the bone, or a mass in the symptoms.
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Imaging Tests: Because the signs and symptoms of adamantinoma resemble many other bone tumors, the healthcare provider may use several imaging tests to distinguish between different tumors and make an exact diagnosis.
These include:
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X-rays: These tests show clear pictures of dense structures, particularly the bones, and help detect bone tumors. Different types of tumors show different characteristics on X-ray. For example, an adamantinoma has a "soap bubble" appearance in x-rays.
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Other Imaging Scans: Magnetic resonance imaging (MRI) and computed tomography (CT) scans help define the tumor and provide more detailed information. A CT or MRI scan will show the provider more precisely where the tumor is located and its specific characteristics. For example, a CT scan enables the provider to determine if the adamantinoma tumor has broken through an area of the bone.
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Biopsy: It may be needed to confirm whether the tumor is an adamantinoma or another bone tumor. A biopsy involves taking a tissue sample of the tumor and examining it under a microscope.
If the healthcare provider diagnoses the tumor as adamantinoma, additional testing may be needed to determine whether the disease has spread to other areas.
How Is Adamantinoma Treated?
Treatment includes:
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Nonsurgical Treatment: The healthcare provider may recommend wearing a brace if the tumor weakens the bone enough to make it bow or change shape (bone deformity). This may also prevent the tumor from causing bone fractures.
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Surgical Treatment: Surgery is the most effective option for treating adamantinomas. If the entire tumor and all cancer cells are removed adequately, there is a good possibility of being cured. However, if some cancer cells remain, there is a greater risk of cancer returning to the same spot or a different body part. In addition, Adamantinomas tend not to respond to other cancer treatments, such as radiation and chemotherapy. When possible, the surgeon removes the tumor leaving the healthy parts of the body, but in some cases, it is necessary to remove the limb along with the adamantinoma tumor. The limb can be reconstructed with surgery to maintain its functioning. Amputation for adamantinoma is not reported to improve survival rates compared to limb-preserving surgery. In addition, because of the high recurrence, curettage is often not recommended.
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Recovery: Once the adamantinoma tumor has been removed by surgery, it is essential to keep regular appointments with the healthcare provider to catch it early if it does come back. After surgery, the provider may take more X-rays and other imaging tests to confirm that the tumor has been removed. How long it will take for a person to resume daily activities varies, depending on the tumor's size and where it was located. The doctor often provides specific instructions to guide rehabilitation.
What Is the Outlook for People With Adamantinoma?
The outlook depends on many factors, such as:
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Where the tumor is in the body.
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If cancer has spread to other parts of the body.
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How much of the tumor was removed during surgery.
After inadequate surgery, the chances of recurrence of the tumor are high. The risk factors for recurrent or metastatic disease are:
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Being male.
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Symptoms of less than five years duration.
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Young age less than 20 years.
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Pain.
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Initial treatment by curettage or resection.
What Are the Complications of Adamantinoma?
If left untreated, it can lead to severe complications that can affect a person's quality of life. Some of the complications of adamantinoma include:
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Bone Fracture: The tumor weakens the bone and makes it prone to fractures, which can cause severe pain and immobility.
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Nerve Compression: Adamantinoma can put pressure on the nerves, causing numbness, tingling, and weakness in the affected area.
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Joint damage: As the tumor grows, it can damage the surrounding joint, leading to stiffness, pain, and difficulty in movement.
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Amputation: In severe cases, the tumor may require amputation of the affected limb, which can significantly impact a person's life.
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Metastasis: In some cases, cancer can spread to other parts of the body, such as the lungs or other bones, making it difficult to treat.
Conclusion
Adamantinomas are cancerous bone tumors that most often occur in the tibia of adolescents and young adults after the bones stop growing. As it is a rare condition, little is known about what causes it. However, adamantinoma is a serious condition that causes bone deformity or fractures and often returns to the same bone location, even many years later. Therefore, long-term close monitoring of adamantinoma by a healthcare provider is necessary because of the risk of recurrence. Treatment is fundamental for survival, but it is possible to recover fully. Surgery is usually recommended to remove the tumor and stabilize the bone.
