Cystic lesion of the bone is one of the common challenges that might be encountered by orthopedic surgeons. Aneurysmal bone cyst (ABC) is a major differential diagnosis in such lesions. Although first described in 1942 by Jaffe and Leichstein [
ABC is a benign expansile osteolytic lesion that typically affects the metaphysis of long bones in young patients during their second decade of life [
ABC can be either primary with no preexisting lesions or secondary to other underlying pathologies [
Several ABC treatment modalities had been utilized including wide resection [
In this cohort, we present a group of patients who had one or more of the unusual features of ABC. In addition, the diagnostic and management considerations of these patients with such unusual features are presented.
This retrospective study involved review of the medical records of patients with primary ABC diagnosis who were treated at King Abdullah University hospital from January 2009 to June 2018. Patients included in this cohort have one or more of the following features: the less common clinical presentation with a palpable mass or with a pathological fracture especially at an unusual age, the cyst presented at rare locations, the radiological findings suggestive of other differential diagnoses especially sarcoma, and the histopathological examination, after either open or needle biopsy, suggested other diagnoses or could not exclude an underlying more serious pathology.
The management approach, outcome, and follow-up were reviewed for patients considered to have one or more of these unusual ABC features. This study was approved by the University Research Committee.
A total of 25 patients were included as having one or more of the unusual features of ABC. There were 17 males and 8 females. Their average age at the time of diagnosis was 12.8 years (3 to 32 years). 12 patients were younger than 10 years, among which 7 patients were 5 or less years of age. While 7 patients presented during the second decade, 6 patients were older than 20 years.
Regarding clinical presentation, most patients (15/25) presented with localized pain. Four patients had a palpable mass as their initial complaint (Figure
(a) Posterior Scapular mass with broad scar after resection attempt. (b) Axial CT showing soft tissue mass extending posterior to the scapula.
(a) AP X-ray with pathological fracture through a diaphyseal ABC. (b) AP X-ray after intralesional resection/curettage followed by fracture fixation with plate and screws.
The anatomical location of the reported cysts included long and flat bones (Figure
Anatomical distribution of aneurysmal bone cysts.
(a) Axial CT showing destruction of the anterior tibial cortex with extension into soft tissue. (b) Coronal CT showing ill-defined distal tibial lesion with cortical destruction.
(a) Lateral elbow X-ray showing expansile cystic lesion involving the whole olecranon. (b) AP and lateral elbow X-rays after surgery with olecranon anatomical locking plate. (c) Lateral X-ray 4 years after removal of metal showing complete healing of the lesion.
(a) AP X-ray of the humerus showing cystic lesions involving the proximal and midhumerus. (b, c) Sagittal and axial CT for the same patient showing expansile cysts of the mid and proximal humerus, respectively.
Radiological workup included primarily X-ray imaging. CT, MRI, and bone scan were done selectively. The radiological evaluation suggested ABC as the primary differential diagnosis in 17/25 patients. Sarcoma was the primary radiological diagnosis in two patients (Figures
All patients in this study had a final pathological diagnosis of primary ABC among which two patients with distal humerus (Figure
(a) AP X-ray of the distal humerus solid variant ABC about 4 years after surgery showing signs of recurrence. (b) X-ray repeated one year later with no further intervention showing almost complete healing and remodeling of the cyst.
(a) AP Femur X-ray with proximal femur cyst diagnosed as benign fibrous histiocytoma. (b) The patient presented 2 years later with a pathological fracture. Final pathology revealed ABC. (c) Lateral X-ray of proximal femur with external fixator showing partial healing of the cyst and a well-maintained fracture reduction about 6 weeks after surgery.
Biopsy methods included open and core needle biopsy in 3 and 7 patients, respectively. While open biopsy confirmed ABC diagnosis in 2 patients, a more serious pathology could not be excluded in the third patient. Core needle biopsy provided the diagnosis in 2 patients while it was inadequate in 2 other patients. In the remaining 3 patients, the diagnoses were unicameral bone cyst, nonossifying fibroma, and giant cell tumor of bone.
As for treatment, wide resection was performed in 4 patients. Intralesional resection/curettage with bone grafting was done in the rest of the patients. No adjuvants were added after curettage in 10 patients. Different adjuvants including bone cement, liquid nitrogen, and hydrogen peroxide were used in 1, 3, and 7 patients, respectively. Different bone graft options including demineralized bone matrix (DBM), allograft chips, autograft, and tricalcium phosphate were used either alone or in combination. Different orthopedic hardware options were used including plates (Figure
The follow-up period of these patients after treatment ranged from 12 months to more than 120 months with an average of 55.2 months. While none of the patients who had wide resection as their treatment developed a recurrence, 7 of the 21 patients who were treated with intralesional resection/curettage and bone grafting developed at least one recurrence (Table
Clinical and management features of the 7 recurrent ABC patients.
Location | Age (years) | Sex | Adjuvant | Bone graft | Time to first recurrence (months) |
---|---|---|---|---|---|
Distal HumerusS | 8 | F | NO | Chips, Vitoss | 48 |
Proximal Humerus | 4 | M | H2O2 | Chips | 24 |
Distal TibiaS | 8 | M | LN | Chips | 6 |
Proximal FemurP | 13 | M | Cement | BC | 55 |
Proximal FemurP | 3 | M | No | DBM | 24 |
Proximal Femur | 5 | M | LN | DBM, chips | 12 |
Proximal HumerusP | 8 | M | No | DBM | 37 |
M: male; F: female; H2O2: hydrogen peroxide; LN: liquid nitrogen; BC: bone cement; DBM: demineralized bone matrix; chips: allograft chips; Vitoss: calcium triphosphate bone graft substitute. SSolid ABC variant. PPathological fracture.
This study investigates the different unusual clinical, radiological, and histopathological features of ABC that can reflect significantly on the management approach.
In this study, most patients (18/25) were either younger than 10 years of age or older than 20 years. This age can represent an unusual age since the peak incidence of ABC occurs in the second decade of life [
ABC most commonly presents with a localized pain [
The unusual ABC locations in this study include the scapula, the olecranon, the hamate, the calcaneus, and the first metatarsal bone [
ABC has a variable radiological appearance with no pathognomonic radiological features [
The role of image guided needle biopsy prior to the definitive surgery is debated [
The optimal treatment of ABC is controversial [
ABC treatment modalities and their recurrence rates reported by different series.
Authors | Year | Main treatment | Patients ( |
Recurrence rate (%) |
---|---|---|---|---|
Vergel De dios et al. [ |
1992 | Curettage and bone graft | 124 | 21.8 |
Marcove et al. [ |
1995 | Curettage and cryosurgery | 51 | 17.6 |
Marcove et al. [ |
1995 | Curettage and bone graft | 44 | 59 |
Mankin et al. [ |
2005 | Curettage and allograft | 101 | 21 |
Rastogi et al. [ |
2006 | Sclerotherapy | 72 | 2.7 |
Varshney et al. [ |
2010 | Sclerotherapy | 45 | 6.7 |
Rossi et al. [ |
2010 | Selective arterial embolization | 36 | 39 |
Steffner et al. [ |
2011 | Curettage, burring, and argon beam coagulation | 40 | 7.5 |
Reddy et al. [ |
2014 | Curopsy | 102 | 18.6 |
Erol et al. [ |
2015 | Curettage, burring, and graft | 59 | 7 |
Terzi et al. [ |
2017 | Selective arterial embolization | 23 | 26 |
Rossi et al. [ |
2017 | Selective arterial embolization | 88 | 18.2 |
Zhu et al. [ |
2017 | Radiation | 12 | 0 |
Palmerini et al. [ |
2018 | Denosumab | 9 | 22.2 |
Aiba et al. [ |
2018 | Endoscopic curettage | 30 | 10 |
Syvänen et al. [ |
2018 | Curettage and bioactive glass | 18 | 11 |
Wide resection of ABC can be associated with significant morbidity. However, it can be indicated especially in expandable locations in which significant functional deficit is not expected after resection [
As for pathological fractures treatment, several authors had suggested that a formal histopathological diagnosis should be obtained prior to further interventions [
Recurrence rates after different therapeutic approaches vary widely, ranging from 0% to more than 59% [
The rare atypical solid variant of ABC has been reported by several authors to have a better prognosis with lower recurrence risk compared to the usual ABC [
Late recurrence, more than 3 years after treatment (Table
This study presented multiple unusual features of ABC including unusual age, rare locations, and nondiagnostic radiological and histopathological findings. These features can complicate both the diagnosis and management of ABC. Given these features, especially with pathological fractures, a well-planned incision, the use of frozen section examination, and the application of either external fixation or plate osteosynthesis for fracture fixation can be recommended. Recurrence is common especially in young males with proximal femur cyst. Closer follow-up can be warranted.
The data used to support the findings of this study are available from the corresponding author upon request.
This study was approved by the IRB committee of Jordan University of Science and Technology.
The authors declare that they have no conflicts of interest.
ZM was responsible for data collection, analysis, study design, and manuscript writing; SA contributed to data collection and manuscript writing; MN was responsible for study design, data collection, and manuscript writing; and OA and AA analyzed the data and wrote the manuscript.