| Aneurysmal bone cyst | |
|---|---|
| Other names | Not recommended: Giant cell reparative granuloma of small bone, giant cell lesion of small bones[1] |
 | |
| A. X-ray: osteolytic lesion in tibia near knee. B/C/D/E. MRI with E showing fluid levels. | |
| Specialty | Orthopedics[1] |
| Symptoms | Pain, swelling, pressure related neurological symptoms[1] |
| Causes | Unknown[1] |
| Diagnostic method | Medical imaging:CT scan,X-ray,MRI,bone scan.[1] |
| Differential diagnosis | Telangiectatic osteosarcoma[1] |
| Treatment | Surgery[2] |
| Prognosis | 20-70% recur after curettage.[1] |
| Frequency | Rare,[3] ~0.15 cases per one million per year.[1] 80% age <20 years.[1] M=F[1] |
Aneurysmal bone cyst (ABC) is anon-cancerousbone tumor composed of multiple varying sizes ofspaces in a bone which are filled with blood.[1][4] The term is a misnomer, as the lesion is neither ananeurysm nor acyst.[5] It generally presents with pain and swelling in the affected bone.[1] Pressure on neighbouring tissues may cause compression effects such as neurological symptoms.[1]
The cause is unknown.[1] Diagnosis involvesmedical imaging.[1]CT scan andX-ray show lytic expansion lesions with clear borders.[1]MRI reveals fluid levels.[1]
Treatment is usually by curettage, bone grafting or surgically removing the part of bone.[2] 20–30% may recur, usually in the first couple of years after treatment, particularly in children.[2]
It is rare.[3] The incidence is around 0.15 cases per one million per year.[1] Aneurysmal bone cyst was first described by Jaffe and Lichtenstein in 1942.[5][6]
The afflicted may have relatively small amounts of pain that will quickly increase in severity over a time period of 6–12 weeks. The skin temperature around the bone may increase, a bony swelling may be evident, and movement may be restricted in adjacent joints.[7]
Spinallesions may causequadriplegia and patients with skull lesions may have headaches.[citation needed]
Commonly affected sites aremetaphyses ofvertebra,flat bones,femur andtibia.[8] Approximate percentages by sites are as shown:[citation needed]
Aneurysmal bone cyst has been widely regarded a reactive process of uncertain cause since its initial description by Jaffe and Lichtenstein in 1942. Many hypotheses have been proposed to explain the cause and pathogenesis of aneurysmal bone cyst, and until very recently the most commonly accepted idea was that aneurysmal bone cyst was the consequence of an increased venous pressure and resultant dilation and rupture of the local vascular network. However, studies by Panoutsakopouluset al. and Oliveiraet al. uncovered the clonal neoplastic nature of aneurysmal bone cyst. Primary cause has been regarded arteriovenous fistula within bone.[9]
The lesion may arise de novo or may arise secondarily within a pre-existing bone tumor, because the abnormal bone causes changes inhemodynamics. An aneurysmal bone cyst can arise from a pre-existingchondroblastoma, achondromyxoid fibroma, anosteoblastoma, agiant cell tumor, orfibrous dysplasia. A giant cell tumor is the most common cause, occurring in 19–39% of cases. Less frequently, it results from somemalignant tumors, such asosteosarcoma,chondrosarcoma, andhemangioendothelioma.[citation needed]
Histologically, they are classified in two variants.[citation needed]
According to Buraczewski and Dabska, the development of the aneurysmal bone cyst follows three stages.[5]
| Stage | Description |
|---|---|
| Initial phase (I) | Osteolysis without peculiar findings |
| Growth phase (II) |
|
| Stabilization phase (III) | Fully developed radiological pattern |
They can also be associated with aTRE17/USP6 translocation.[10]
Aneurysmal bone cysts may be intraosseous, staying inside of the bone marrow. Or they may be extraosseous, developing on the surface of the bone, and extending into the marrow. A radiograph will reveal a soap bubble appearance.[citation needed]
X-ray andCT scan show lytic expansion lesions with clear borders.[1] Expansion of cortex gives the lesion a balloon-like appearance. Larger lesions may appear septated.[11]MRI reveals fluid levels.[1]Bone scan shows outer radiotracer uptake, with a central dark area.[1][11]
Following conditions are excluded before diagnosis can be confirmed:[12]
Curettage is performed on some people,[13] and is sufficient for inactive lesions. The recurrence rate with curettage is significant in active lesions, and marginal resection has been advised.Liquid nitrogen,phenol,methyl methacrylate are considered for use to kill cells at margins of resected cyst.[9]
20–70% recur after curettage.[1]
It is rare.[3] The incidence is around 0.15 cases per one million per year.[1] 80% occur in people age less than 20 years.[1] It is second most common tumor of spine and most common benign tumor of pelvis inpediatric population.[9] Males and females are equally affected.[1]
