A Case Report of Multiple Aneurysmal Bone Cysts

Discussion

An aneurysmal bone cyst is a rare disease, comprising about 1% to 2% of primary bone tumors, and 13.7% of the tumor-like lesions. Most of the patients are teenagers. The most common site is the metaphysical position of the long bone of the extremities and spine. It has been suggested by some orthopedists that the etiological factors include the formation of a local venous thrombosis or abnormal arteriovenous communication on the basis of a regional lesion, resulting in a local hematological blockage which brings about a continuous increase of the intravenous tension, an expansion of the blood vessel lumen and secondary local bone absorption, thus forming the cyst. The expanded vessel lumen has the features of a thin wall and close adherence to the sclerotin that makes it difficult for the vessel to contract for hemostasis, therefore, there is usually a pale yellow fluid hemorrhage in the diseased region.

Owing to the lack of contractible vessel lumens, scraping of the lesions should first be conducted, in order to prevent an excessive blood loss. Further treatments should be performed, such as resetting the bone and conducting a bone graft etc. The X-ray examination usually indicates a local translucent area, an expanded or osteolytic destruction, and it sometimes presents an obscure boundary, with a pathologic fracture. It is easily confused with a malignant tumor. Therefore it should be distinguished, at diagnosis, from a giant cell bone tumor, angiectatic osteosarcoma and solitary bone cyst.

Previous reports in the literature^[1] suggest that the preferred mode of treatment of a simple lesion should be a curettage plus a bone graft, as the cure rate with this treatment has accounted for approximately 70% to 90% of the patients. However, a second or even more operations are needed once a relapse occurs. A thorough intraoperative curettage of the lesion is the key for preventing a post-operative recurrence. Low dose radiation therapy (26~30 Gy) can be performed for some patients with a difficult resection or with a recurrence. With this treatment the rate of local control may also reach 90%.

Our patient was diagnosed as having a simple bone cyst on the left proximial humerus and a symmetric aneurysmal bone cyst on both distal humeri. To our knowledge a case similar to this has not been previously reported in the literature. At present, the patient has not received a treatment on the distal lesion of the right radial bone, while a follow-up of the case is still continuing.