Aneurysmal bone cysts, commonly found in the hip, shoulder, and knee regions, are harmless bone tumors that typically occur in boys between the ages of 5 and 15. These tumors are benign, not cancerous. However, an aneurysmal bone cyst can cause pain and thin the bone, leading to fractures.

This condition, which is particularly common in boys, can often be associated with traumatic events that may occur due to their mobility. Aneurysmal bone cysts most commonly occur in the hip, shoulder, and knee regions. The exact cause of these tumors, how they develop, and why they occur are still unknown.

Treatment for an aneurysmal bone cyst may vary depending on the damage it causes. These tumors, which tend to recur, should be monitored by specialists, and a treatment plan should be developed if necessary. This is determined by the patient's age, general health, and tumor location.

What are the factors affecting the formation of aneurysmal bone cysts?

The exact causes of aneurysmal bone cyst formation are not yet fully understood. Such cysts generally do not cause any significant symptoms, and the pain is usually mild and may increase over time. Significant symptoms may not occur unless a fracture occurs due to mechanical problems. In some cases, they may be discovered incidentally on X-rays taken in connection with other symptoms.

Aneurysmal bone cysts can be caused by weakened bone integrity and minor trauma. This can lead to a bone crack or fracture. However, the cyst typically presents no symptoms such as swelling or pain. These swelling and pain are often more pronounced, especially when a bone crack or fracture occurs. Therefore, an aneurysmal bone cyst is often detected incidentally before it causes significant symptoms.

Aneurysmal bone cyst symptoms and effects

Aneurysmal bone cyst may present itself with the following symptoms:

• Pain: The most common symptom of an aneurysmal bone cyst is pain. Pain often occurs because the cyst causes thinning and weakening of the bone over time. It may be mild initially, but it can become more pronounced as the bone thinning increases or a fracture occurs. It can progress to constant pain.
• Bone thinning: An aneurysmal bone cyst causes thinning and weakening of the bone. This can lead to decreased bone integrity and fractures.
• Limited mobility: An aneurysmal bone cyst can cause limited mobility due to bone weakness. This can be particularly restrictive in the affected area, especially if a fracture occurs.
• Fractures: Aneurysmal bone cysts can cause fractures due to impact due to bone weakness. These fractures often require a different treatment approach than other conventional fractures.

Symptoms of an aneurysmal bone cyst often become apparent over time and may require treatment. It's important to consult a healthcare professional, especially if you experience pain or if bone weakness becomes apparent.

How is aneurysmal bone cyst diagnosed? 

The patient's clinical symptoms, age, and location of the suspected bone play a significant role in diagnosing an aneurysmal bone cyst. Initially, the patient's symptoms and risk factors are evaluated. X-rays often reveal signs such as bone thinning or increased diameter. However, these signs may not be evident in the early stages of the disease.

Imaging techniques such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) are used in the diagnostic process. MRI provides a more detailed view of bone damage, edema, and cystic appearance. Computed Tomography (CT) helps visualize bone damage and fractures more clearly.

Another important step in the diagnostic process is a biopsy. To make a definitive diagnosis, tissue samples taken from the area suspected of an aneurysmal bone cyst are evaluated through histopathological examination. This biopsy is performed under light sedation using specialized needles and allows direct examination of the tumor tissue.

Samples taken after the biopsy are evaluated by a multidisciplinary tumor board. This board typically consists of specialists in orthopedics and traumatology, radiology, pathology, and oncology. After a definitive diagnosis is made, the appropriate surgical treatment plan is developed, and the most appropriate treatment method for the patient's condition is determined and implemented.

How is aneurysmal bone cyst treated?

Treatment for aneurysmal bone cysts can vary depending on the location of the tumor and the damage it has caused to the bone. Two main treatment methods are generally used:

Surgical method:

• Surgery is preferred if the aneurysmal bone cyst is confined to the tumor site and can be completely removed. However, even with this method, there is a risk that tumor cells may remain behind at the cellular level, which may increase the risk of recurrence.
• During surgery, the area containing the tumor is removed, and then the removed area is filled with bone graft or bone cement, a special chemical alloy.

Liquid nitrogen treatment:

• Adjuvant treatment methods using chemical substances such as liquid nitrogen (nitrogen), phenol, and alcohol can be applied to prevent the recurrence of aneurysmal bone cysts.
• The liquid nitrogen spray method involves spraying liquid nitrogen on tumor cells invisible to the naked eye within the bone, momentarily dropping the temperature to -180°C and then returning to room temperature to break down the tumor cells.
• In the next step of treatment, once the tumor cells have been destroyed, the resulting void is filled using bone grafts or bone cement. Bone cement, in particular, not only increases mechanical strength but also inhibits tumor growth.

In cases of small bones or those that cause extensive bone destruction, complete bone removal and bone transplantation may be possible. These treatment options are evaluated by doctors based on the patient's condition and the characteristics of the tumor, and the appropriate treatment plan is determined.

Is aneurysmal bone cyst cancerous?

An aneurysmal bone cyst is not cancer. While the word "tumor" is often associated with cancer, an aneurysmal bone cyst is not a malignant type of bone cancer. These types of cysts are considered benign, meaning they are not life-threatening. However, an aneurysmal bone cyst may have a tendency to reoccur in the bone where it first formed. These cysts, which usually affect a localized and limited area, can lead to bone thinning and fractures if left untreated.

Does aneurysmal bone cyst cause death?

An aneurysmal bone cyst itself is not a fatal condition. It is usually a benign bone tumor and does not directly cause death. However, in rare cases, an aneurysmal bone cyst can grow, particularly around the pelvis and hip bones.

In this case, factors such as the tumor growing too large, starting treatment too late, or being too advanced to be surgically removed can cause problems in the organs to which the tumor has spread and can be life-threatening. However, these situations generally represent rare exceptions.

In general, once an aneurysmal bone cyst is diagnosed and an appropriate treatment plan is established, its potential for death is low. Early initiation of treatment and regular follow-up are important to minimize potential complications.

Does aneurysmal bone cyst recur?

Yes, aneurysmal bone cysts are prone to recurrence. While aneurysmal bone cysts are generally classified as benign, they carry a risk of recurrence due to their locally aggressive nature. The risk of recurrence may vary depending on the extent of bone spread of the tumor, the success of the surgical intervention, and the treatment method.

What are the possible consequences if an aneurysmal bone cyst is not treated?

If left untreated or detected late, an aneurysmal bone cyst can completely dissolve the bone and spread to surrounding soft tissues, making treatment difficult. Aneurysmal bone cysts are generally considered benign, locally aggressive bone tumors. However, progression of these tumors can lead to bone weakening and thinning.

Previously diagnosed and untreated aneurysmal bone cysts can lead to bone weakness, leading to fractures and loss of function. Furthermore, untreated aneurysmal bone cysts can spread to surrounding tissues, limiting treatment options and making surgical intervention more difficult.