Review Question - QID 3691

The history and radiographs are consistent with a pathological fracture through a unicameral bone cyst (UBC) in the child's humerus. The radiograph shows a lytic, expansile lesion with well-defined borders, no soft tissue mass, no significant matrix, and no periosteal reaction. The CT scan confirms this lesion is benign appearing with sharp sclerotic borders. Given the benign appearance, location, and history, biopsy is not required as a diagnosis of UBC can be made with the information provided.

The initial treatment of a pathological fracture through a benign bone cyst includes immobilization while the fracture heals. If this same lesion were present in a weight bearing bone, such as the proximal femur, then the treatment choice becomes more problematic and internal fixation needs to be considered to allow the child to mobilize. While many adjuvants have been tried in the treatment of UBCs, none have shown to be advantageous.

Dormans and Pill review the treatment of pathological fractures through bone cysts. They focus on the crucial identification of the specific diagnosis as the treatment of pathological fracture through a benign cyst is much different than the same fracture through a malignant neoplasm.

Wilkins reviews unicameral bone cysts in his JAAOS article. With appropriate imaging and patient history, a diagnosis of UBC can often be identified without advanced studies or surgical biopsy. As most UBCs will heal spontaneously, treatment includes immobilization and observation, except in tumors which occur in weight bearing bones or in situations where pathological fracture is preventable.

Incorrect answers
1) Biopsy - as discussed above, biopsy is not necessary given the benign appearance, location, and history.
3,4,5) Adjuvant therapy or aggressive surgical resection is not indicated for a benign bone tumor.