Simple bone cysts are relatively common in children. When they present to a musculoskeletal oncology unit, they are usually treated by a variety of methods that range from observations following fracture to surgically curettage. The outcome is usually good.

Very little is written in the literature regarding adults with a cystic bone lesion.

We present 10 consecutive skeletally mature patients who presented with a benign cystic bone lesion. The mean age at diagnosis was 38 years (20–60 years). Three patients has a cyst in the foot, three in the hip, two in the knee, one in the pelvis and the remainder in the shoulder. Full work up, including biopsy, was performed in all cases. All hip lesions required internal fixation for actual or impending fractures. The average follow up was 1.5 years. The surgical outcome was good in all cases.

The histological features are similar in all cases. Cementum, as found in Unicameral Bone Cysts, is not seen. This may present a new entity that is not described in the literature.