Unicameral bone cyst

Unicameral Bone Cyst

A unicameral bone cyst (UBC), also known as a simple bone cyst, is a benign fluid-filled bone cavity that is most commonly found in children and adolescents. These cysts are typically located in the long bones, such as the humerus and femur, and are often discovered incidentally or after a pathological fracture.

Presentation

Unicameral bone cysts are usually asymptomatic and are often discovered when a fracture occurs through the cyst. The cysts are most commonly found in the metaphysis of long bones, particularly the proximal humerus and femur. On rare occasions, they may be found in other bones such as the pelvis or calcaneus.

Pathophysiology

The exact cause of unicameral bone cysts is not well understood. It is believed that they may result from a developmental anomaly in the growth plate, leading to a fluid-filled cavity within the bone. The cyst is lined by a thin membrane and filled with a clear, yellowish fluid.

Diagnosis

Diagnosis of a unicameral bone cyst is typically made through imaging studies. X-rays reveal a well-defined, radiolucent area within the bone, often with thinning of the cortex. MRI and CT scans can provide more detailed information about the cyst's size and its effect on surrounding bone structures.

Treatment

Treatment of unicameral bone cysts depends on the size and location of the cyst, as well as the presence of symptoms. Small, asymptomatic cysts may be monitored with regular imaging. Larger cysts or those causing symptoms may require intervention. Treatment options include:

• **Aspiration and injection**: The cyst can be aspirated and injected with corticosteroids or bone marrow to promote healing.
• **Curettage and bone grafting**: Surgical removal of the cyst lining followed by filling the cavity with bone graft material.
• **Internal fixation**: In cases of fracture, internal fixation with plates or screws may be necessary.

Prognosis

The prognosis for unicameral bone cysts is generally good, especially with appropriate treatment. However, recurrence is possible, and regular follow-up is recommended to monitor for any changes.

Related pages

• Bone cyst
• Pathological fracture
• Orthopedic surgery

References

• Dormans, J. P., & Sankar, W. N. (2006). Unicameral bone cysts. Journal of the American Academy of Orthopaedic Surgeons, 14(4), 217-224.
• Capanna, R., & Campanacci, D. A. (2001). Unicameral and aneurysmal bone cysts. Clinical Orthopaedics and Related Research, (382), 25-36.

External links

• [Radiopaedia: Unicameral bone cyst](https://radiopaedia.org/articles/unicameral-bone-cyst)

MRI of a unicameral bone cyst in the humerus

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