Epidemiology
An expansile lesion of children, adolescents, and young adults. It can grow quickly and look aggressive on imaging, so the diagnosis is confirmed and associated lesions ruled out before treatment.
Basic features
Local growth with blood-filled cavities; it may cause pain, swelling, or fracture. A primary aneurysmal bone cyst is now defined by a rearrangement of the USP6 gene, a test that helps confirm it and separate it from a cystic component secondary to another lesion —in particular a telangiectatic osteosarcoma, which can look almost identical on imaging.
Usual treatment
Curettage with adjuvants, embolization or sclerotherapy depending on location, size, and structural risk. In very destructive or recurrent lesions, or those in an expendable bone, en-bloc resection is the alternative to curettage and offers the safest local control. In lesions that are difficult to operate on or that recur, denosumab may be considered as an additional treatment by an experienced team. In children and adolescents both its use and its withdrawal require medical and laboratory monitoring, because stopping it can cause a marked rise in blood calcium.
Outcomes and prognosis
Good control in most cases; local recurrence after curettage is not negligible and calls for radiological follow-up. It does not metastasize.