Unicameral bone cyst
| Unicameral bone cyst | |
|---|---|
| Other names | Solitary bone cyst, unicameral bone cyst (not recommended) |
| MRI scan: simple bone cyst humerus of a 13 year old boy | |
| Specialty | Orthopedics |
| Symptoms | Pain, swelling, reduced movement, pathological fracture or no symptoms |
| Causes | Unknown |
| Diagnostic method | Medical imaging |
| Frequency | Age less than 20 years. M:F ratio: 2:1 |
A unicameral bone cyst, also known as a simple bone cyst, is a cavity filled with a yellow-colored fluid. It is considered to be benign since it does not spread beyond the bone. Unicameral bone cysts can be classified into two categories: active and latent. An active cyst is adjacent to the epiphyseal plate and tends to grow until it fills the entire diaphysis, the shaft, of the bone; depending on the invasiveness of the cyst, it can cause a pathological fracture or even destroy the epiphyseal plate leading to the permanent shortening of the bone.
A latent cyst is located away from the epiphyseal plate and is more likely to heal with treatment. It is typically diagnosed in under 20 year olds. Although unicameral bone cysts can form in any bone structure, it is predominantly found in the proximal humerus and proximal femur; additionally, it affects males twice as often as females.
Treatment options for unicameral bone cysts include invasive approaches such as injections, curettage and surgical fixation, and non-invasive procedures including observation to see if it does not get worse or resolves on its own, plaster casting or restricted activity.