What is Adamantinoma?
Adamantinomas are uncommon and slightly cancerous bone tumors that are mostly seen in the central and end parts of the shinbone. The reason they are named adamantinomas is because of their similarities, from a microscopic perspective, to ameloblastoma—a type of tumor typically found in the lower jaw. When looked at under a microscope, adamantinomas show a mix of skin-like cells and bone-fibrous components.
There are two kinds of adamantinomas—traditional and differentiated—with the latter looking similar to a condition called osteofibrous dysplasia. Even though imaging techniques have improved, the main way to accurately diagnose adamantinomas is through microscopic examination of the tissues.
What Causes Adamantinoma?
The exact cause of adamantinoma, a type of tumor, is still a mystery. One popular theory suggests it may come from skin cells that were misplaced during our early development in the womb. This theory gets some support from the fact that adamantinoma frequently occurs in the front part of the shin bone, an area where the bone forming process is closest to the skin.
Other studies using immune response testing and highly detailed imaging have indicated that adamantinoma may come from a specific type of skin cell known as an epithelial cell. However, there is ongoing debate about whether adamantinoma is linked to another bone condition called osteofibrous dysplasia. If these two conditions are connected, it could have important implications for how we diagnose, predict the course of, and treat adamantinoma.
Risk Factors and Frequency for Adamantinoma
Adamantinoma is a rare type of bone tumor, making up about 0.4% of all bone cancers. This disease slightly affects more males than females, with the ratio being 5:4. It mostly affects people between the ages of 20 and 40 and is unusual in children and older adults.
- Adamantinoma is a rare bone tumor, accounting for 0.4% of such cases.
- It tends to affect males slightly more, with a ratio of 5:4 compared to females.
- Middle-aged individuals between 20 and 40 are the most affected group.
- The disease is rare in both children and the elderly.
- Although it most commonly affects the front part of the shinbone, it can also occur in other areas such as the fibula, ulna, femur, humerus, and radius.
Signs and Symptoms of Adamantinoma
Adamantinomas are typically slow-growing tumors that progress gradually over time. People with this condition might notice a swelling that grows slowly, and this can sometimes be painful. In some cases, the tumor can cause changes in the shape of bones or increase the risk of fractures, which usually prompts individuals to seek medical help. If the tumor affects the spine, neurological symptoms like numbness or weakness may show up. Interestingly, about 23% of people with adamantinomas experience such fractures.
Because the disease progresses at a slow pace and the symptoms are quite subtle initially, many people don’t immediately recognize that they have a problem. They might put up with the symptoms for years before finally seeking medical help, which can lead to a delay in diagnosis and treatment.
Testing for Adamantinoma
When an X-ray is taken of a patient with adamantinoma, which is a rare type of bone tumor, it often appears as a well-defined tumor within the layer of bone called the cortex. The tumor’s appearance resembles a pattern of multiple bubbles, making it easy to distinguish. This particular appearance is due to transparent spots within the tumor surrounded by ring-shaped densities. It’s not unusual for several such spots to be detected within the same bone.
The usual presentation of this tumor is confined within the bone’s cortex and tends to grow along the bone. However, there can be situations where the tumor breaks through the cortex to invade the inner part of the bone, the surrounding bony layer called the periosteum, or adjacent soft tissues. These cases are typically associated with a distinct type of bony reaction around the lesion.
For better visualisation of adamantinomas and to see any extension into the surrounding soft tissue, a computed tomography (CT) scan is often carried out. The CT scan plays a crucial role in diagnosing these tumors, but it may not provide detailed images of the tumor’s extension within the bone. Importantly, CT scans can also help detect if the cancer has spread to the lungs.
A magnetic resonance imaging (MRI), on the other hand, is extremely useful for outlining the local spread of adamantinomas. It provides detailed pictures of how the tumor has spread within the bone, its involvement with the central part of the bone, and any extension into soft tissues. Doctors find MRI critically useful to mark the boundaries of the tumor without cancer – essential for planning complete surgical removal of the tumor. Furthermore, knowing the spread of the tumor can help decide on the type of surgical reconstruction needed.
On MRI, adamantinomas can show up as either several small nodules in one or more areas or a single, irregularly shaped focus. They usually appear with a lower brightness on T1-weighted images and increased brightness on T2-weighted images of the MRI. Quite importantly though, similar imaging findings can be seen with various other conditions, and are not specific to adamantinomas.
with heterogeneous enhancement. This was a biopsy proven adamantinoma.
Treatment Options for Adamantinoma
Treating a rare type of bone tumor known as an adamantinoma is complex, and there are currently no standard recommendations for its management. It’s key to ensure a cautious biopsy at the start of treatment, while avoiding a process called curettage, which is linked to a higher chance of the tumor reappearing. After curettage, the likelihood of the tumor coming back can be as high as 90%.
The tumor may reappear in up to 32% of cases after a procedure called marginal excision. In a study, those who had a tumor removal procedure experienced a 29% reappearance rate, while 100% of cases treated with curettage saw the tumor return. Because of these findings, experts such as Puchner et al, advocate for wide resections as the best treatment approach.
In treating adamantinoma, the first step involves removing the bone tumor through a process called resection, which includes removing the complete tumor along with a bit of healthy tissue around it. After the tumor is removed, the next step involves repairing the bone damage caused by the excision. Several methods can help address the bone gap, including distraction osteogenesis, intercalary allografts, vascularized autografts, and tailored prostheses or endoprosthesis.
Research has shown that the most successful treatment for adamantinoma is wide excision with clear margins. An investigation by Qureshi et al revealed that 87.2% of patients who had a limb-saving resection survived for 10 years. Out of 70 patients, 50 managed to save their limb, leading to a limb preservation proportion of 84%.
However, adamantinoma can behave relatively unpredictably. In a study by Schutgens et al, 27% of patients experienced a return of adamantinoma after more than 10 years. Furthermore, adamantinoma can spread to various body parts, including the lungs, nearby lymph nodes, and the spine. Given this, people diagnosed with adamantinoma should have long-term observation, typically stretching beyond 15 years, and regular check-ups, involving lung imaging and physical examinations.
For tumors that have spread or returned, surgical removal is recommended. Metastasectomy, removal of metastases, is often the first choice of treatment for lung recurrences. Both radiation and chemotherapy haven’t shown significant impacts on tumor size or survival.
While radiation hasn’t proven to be very effective for treating adamantinoma directly, it can help ease back pain and potentially reduce the need for strong painkillers. In some cases, targeted treatment using tyrosine kinase inhibitors has shown promising results.
In cases where the tumor has returned or when resection and limb preservation aren’t possible options, amputation might be required. It’s important to note that the survival rate doesn’t significantly vary between those who manage to save their limbs versus those who undergo amputation. And due to the high chances of the tumor recurring, curettage is not recommended.
What else can Adamantinoma be?
Several experts have found a strong link between a sort of bone tumor called adamantinoma, specifically the osteofibrous dysplasia-like subtype, and osteofibrous dysplasia – a benign, or noncancerous, bone lesion. The similarities in how these conditions appear on x-rays and scanners, and under the microscope, coupled with their usual presence in the same bone – the tibia (large bone of the lower leg) – can make it difficult to distinguish between them.
Adamantinoma, looking at it clinically, radiologically, and histologically (that is, in the patient’s symptoms, on radiographic images, and under the microscope), can mimic various other bone tumors. These include benign conditions like bone cysts, giant cell tumors, and more serious malignant ones such as chondrosarcoma, angiosarcoma, and metastases (spread from other cancers).
What to expect with Adamantinoma
Adamantinoma is a type of aggressive tumor that has the capacity to spread to other parts of the body. When not fully removed through surgery, it often returns.
Certain factors increase the risk of the tumor coming back or spreading to other parts of the body. These factors include:
* Having symptoms for less than 5 years
* Being male
* Being under 20 years old
* Having pain when first diagnosed
* Initial treatment involving either scraping out the tumor or cutting it out
* The tumor doesn’t have any squamous (or flat) cells
* The tumor has more epithelium (the tissue that lines the outside of the body and internal organs) compared to stroma (the connective tissue that supports organs)
In about 15% to 30% of cases, adamantinomas can spread, most commonly to the lungs, lymph nodes, bones, and organs in the abdomen. A study conducted by Aytekin et al reported that the survival rates for adamantinomas are 98.8% after 5 years and 91.5% after 10 years. The study also found that survival time isn’t affected by factors like gender, age, ethnicity, marital status, where the tumor is located, or when it was detected.
Another study conducted by Houdek et al over 16 years found that of 46 patients studied, the tumor returned in 33% of cases.
Possible Complications When Diagnosed with Adamantinoma
Based on various studies, it appears that adamantinoma, a rare type of bone cancer, has a tendency to come back in around 30% to 35% of patients. The mortality rate, or the likelihood of death, due to adamantinoma is between 6% and 18%. In 12% to 29% of patients, this cancer can also spread to the lung or lymph nodes.
Preventing Adamantinoma
Teaching patients about their condition is an important part of managing adamantinoma, a rare and aggressive bone tumor. Doctors need to clearly explain what adamantinoma is, why it’s unique, and how it behaves. This includes letting patients know that it typically occurs in specific bones like the front of the shinbone and tends to invade nearby areas.
Doctors also need to share common symptoms of adamantinoma with patients. These can include a swelling that grows slowly, and may or may not bring pain. It’s also essential to inform patients about the risk of spreading or ‘metastasis’ – in about 15% to 30% of cases, adamantinoma can spread to the lungs or lymph nodes.
Recovery from adamantinoma won’t be instantaneous. Doctors need to prepare patients for the reality that this bone tumor often comes back, with a recurrence rate of around 33% even after removing the tumor. Long-term care and monitoring are essential to catch any signs of the tumor’s return as early as possible.
Discussing the recovery process, doctors must explain to the patients that healing will require patience and time. They should discuss potential reconstruction options following the tumor removal. These procedures, which can help restore both function and appearance, should be considered and chosen according to the patient’s needs.
Mental health support is a critical part of treating adamantinoma. Doctors should offer emotional support to patients and their families, advising them about available resources for counseling. They should also let patients know that feelings of depression or anxiety are common after a diagnosis, and help is available.
