BONE CYST

circumscribed, benign (noncancerous) lesion, usually saclike and filled with fluid. Unicameral bone cyst affects the long bones or heel bones in children and adolescents and is frequently detected as a result of a pathological fracture. Treatment is by excision and bone graft, but spontaneous healing is common. Aneurysmal bone cyst, usually occurring in young males, consists of a vascular mass causing expansion of bone. Swelling and pain are present; this cyst may regress spontaneously or following X-ray therapy, or it may require excision.