Figure 24-1 CT and MRI of the patient.
Clinical picture :
A 15-year-old male patient with no history of diabetes (DM) or hypertension (HTN) has been known to have rheumatic valvular heart disease (HD) and has been on long-acting penicillin for 3 years. The condition started 1 year ago following direct trauma to the back of the neck, which led to a gradual onset and progressive swelling at the nape of the neck. The swelling has shown a more aggressive course in the last 5 months. The patient has undergone 2 previous sessions of endovascular embolization. Motor function is full power (F.P) and sensory and sphincter functions are intact.
Q1: Describe the radiology findings.
On CT of the craniocervical junction, there is an expansile osteolytic lesion surrounded by a shell of bone and calcification at the level of the C2 and C3 cervical vertebrae, appearing to arise from the lamina and spine. On MRI, it is observed to have multiple septa and fluid-filled cavities. CT also demonstrate evidence of previous embolization.
Q2: What is an aneurysmal bone cyst?
An aneurysmal bone cyst is an expansile osteolytic lesion consisting of highly vascular, honeycomb-like blood-filled cavities separated by connective tissue septa and surrounded by a thin cortical bone shell. It may occur in the spine or skull.
Q3: What are the most common sites for this lesion?
Regionally, it commonly occurs in the lumbosacral junction and craniocervical junction, as shown in this case. Compartmentally, it usually involves the posterior elements of the spine.
Figure 24-2 demonstrate site of these lesions.
Q4: What is the main role of treatment?
Intralesional curettage is the primary treatment target; however, recurrence is very high if not completely excised, reaching up to 40%. In case of recurrence, redo surgery is required. Radiation has no role except it may sometimes be used preoperatively to reduce intraoperative bleeding. Additionally, preoperative embolization is sometimes warranted. Postoperative radiotherapy is considered if the pathology shows malignant transformation.
Q5: What is the origin in this case?
There are several theories regarding the origin:
- It may follow an acute fracture ( as the case).
- It may arise from preexisting tumors like giant cell tumors, fibrous dysplasia, or osteoblastoma.