Targeting receptor-activator of nuclear kappaB ligand in aneurysmal bone cysts: verification of target and therapeutic response

Using Denosumab as a Nonsurgical Management of Aneurysmal Bone Cysts in the Pelvis

Background

Aneurysmal bone cysts (ABCs) are infrequent, benign, and locally destructive lesions that most commonly occur during the first two decades of life. They usually affect the metaphysis of the long bones, but the pelvis is involved in 8%-12% of the cases. The management of pelvic ABCs is a challenging issue due to difficulties in choosing the appropriate approach, adjacent neurovascular bundles, the risk of intraoperative bleeding with difficulty achieving good hemostasis, and the risk of injury to the hip or sacroiliac joints. Limited data exist concerning the use of denosumab as a non-surgical treatment for pelvic ABCs. Our hypothesis was that denosumab might be an effective and safe solo treatment of cases with ABCs in the pelvis.

Methods

We retrospectively assessed 20 patients with ABCs in the pelvis, who were treated by denosumab as a solo agent without surgery. Patients were assessed regarding disease control, the incidence of recurrence and non-oncological complications, and functional outcome.

Results

The mean follow-up period was 38.5 months. Disease control was achieved in 16 patients (80%), with no local recurrence. Tolerable drug-related complications occurred in 15% of cases. The mean Musculoskeletal Tumor Society score was 92.3%.

Conclusions

Denosumab may provide a reliable option in the nonsurgical treatment of ABCs of pelvic origin with expected lower morbidity than the surgical solution and tolerable complications. Further studies on the safety profile and long-term effects of denosumab especially in skeletally immature patients are required.

The Role of En Bloc Resection in the Modern Era for Primary Spine Tumors

STUDY DESIGN

A literature review.

OBJECTIVE

The aim of this review is to provide an overview of benign and malignant primary spine tumors and a balanced analysis of the benefits and limitations of (and alternatives to) surgical treatment with en bloc resection.

SUMMARY OF BACKGROUND DATA

Primary spine tumors are rare but have the potential to cause severe morbidity, either from the disease itself or as a result of treatment. The prognosis, goals, and treatment options vary significantly with the specific disease entity. Appropriate initial management is critical; inappropriate surgery before definitive treatment can lead to recurrence and may render the patient incurable, as salvage options are often inferior.

METHODS

We performed a comprehensive search of the PubMed database for articles relevant to primary spine neoplasms and en bloc spine surgery. Institutional review board approval was not needed.

RESULTS

Although Enneking-appropriate en bloc surgery can be highly morbid, it often provides the greatest chance for local control and/or patient survival. However, there is growing data to support modern radiotherapy as a feasible and less morbid approach to certain primary neoplasms that historically were considered radioresistant.

CONCLUSIONS

Choosing the optimal approach to primary spine tumors is complex. A comprehensive and up-to-date assessment of the evidence is required to guide patient care and to balance the often-competing goals of prolonging life and preserving quality of life.

Denosumab in Giant Cell Rich Tumors of Bone: An Open-Label Multicenter Phase II Study

BACKGROUND

Since giant cell tumors of bone (GCTB) and other giant cell rich tumors of bone (GCRTB) share the histological presence of osteoclastic giant cells and expression of RANK/RANKL, we hypothesized that GCRTB will respond similarly to denosumab as GCTB. The primary objective of this study was to determine the efficacy of denosumab in patients with GCRTB that have recurred or require morbid surgery.

METHODS

In this open-label, multicenter, phase II trial, patients with GCRTB were included (June 2018-March 2020). Recruitment was stopped because of low accrual. Patients received denosumab (120 mg) subcutaneously (SC) on day 1 of every 4-week cycle with a loading dose of 120 mg SC on days 8 and 15.

RESULTS

Three patients were enrolled. One withdrew consent before start of study. The remaining patients had central giant cell granuloma of the jawbone (CGCG). Median treatment duration was 15 cycles (range 12-18). In both subjects, improvement in ossification of lesions was seen. Median follow-up was 28.5 months (range 20-37). One patient developed a recurrence for which surgery was performed.

CONCLUSION

Due to critical emerging real-world data of denosumab in GCRTBs, the study was prematurely stopped and not supportive of use of denosumab for this indication. (ClinicalTrials.gov Identifier: NCT03605199).

Giant sacral aneurysmal bone cyst treated with endovascular embolization

Background

Spine aneurysmal bone cysts (SABC) are osteolytic tumor-like lesions with cystic, blood-filled cavities that represent 15% of all primary spinal bone tumors. The sacrum is a rare site for SABC, and sacral lesions typically carry higher morbidity rates. Here, a 19-year-old female with a large primary multisegmental sacral SABC was successfully managed with 2-staged endovascular embolization.

Case Description

A 19-year-old female presented with progressive worsening of axial lumbosacral pain, and a left L5/S1 radiculopathy. The lumbosacral computed tomography and magnetic resonance studies showed a large (10 cm [AP] × 11 cm [Tr] × 12 cm [CC]) heterogeneous, osteolytic lesion containing multiple fluid-fluid levels. The biopsy confirmed the diagnosis of a primary SABC. She was treated with a 2-staged endovascular embolization that resolved her pain. This was followed by radiographic confirmation of occlusion of the SABC.

Conclusion

A 19-year-old female presented with an atypical SABC that was successfully managed with 2-staged endovascular embolization.

The Role of Denosumab in the Treatment of Primary Tumors of Bone

Many hand surgeons treat benign bone tumors without referral to orthopedic oncologists. However, there have been considerable advances in medical therapy for some of these tumors, with which hand surgeons may not be as familiar. This review focuses on the mechanism and uses of denosumab in the treatment of benign tumors of bone. Although the hand surgeon may not be directly prescribing this therapy, they are often the only physician treating the patient for these conditions. As such, awareness regarding the use of this therapy in reducing pain, decreasing tumor volume, and treatment of potential lung metastases is critical to those taking on these cases without the support of an orthopedic oncologist. This article aims to familiarize hand surgeons with denosumab to help promote knowledge of this therapeutic option and the potential role of this medication in the treatment of primary bone tumors in the hand.

Approach to the Treatment of Expansile Metacarpal Aneurysmal Bone Cysts: A Report of Two Cases

The two cases presented demonstrate the management of aneurysmal bone cysts of the metacarpal, which destroyed the normal bone architecture. Treatment of both cases included wide resection and metacarpal reconstruction with an intercalary fibular allograft. Denosumab use contrasts these two cases and is helpful in reestablishment of a cortical rim for fixation in the absence of a 1-cm margin proximally or distally to preserve the native carpometacarpal and metacarpophalangeal joints. Surgical resection and allograft reconstruction is a viable treatment for expansile metacarpal aneurysmal bone cysts, and neoadjuvant denosumab has utility in creating an ossified margin for fixation.

Surgical Management and Denosumab for Aneurysmal Bone Cysts of the Spine in an Australian Tertiary Paediatric Centre

Aneurysmal bone cysts (ABC) are rare osteolytic, benign but often locally aggressive tumours of the long bones or vertebrae. For spinal ABC, surgical management, embolisation or sclerotherapy alone often carry high morbidity and/or high recurrence rates. Interruption of receptor activator of nuclear factor-kappa B ligand (RANKL) signalling holds promise as an effective therapeutic strategy for these tumours. We aimed to review the approach to surgical management and evaluate the efficacy and safety of denosumab for ABC of the spine in children. Retrospective review of 7 patients treated with denosumab using a standardised protocol for ABC of the spine in a tertiary paediatric centre. Surgical intervention was only conducted if there was spinal instability or significant neurological impairment. Denosumab 70 mg/m² was given 4-weekly for at least 6 months, followed by 2 doses of zoledronate 0.025 mg/kg, aiming to prevent rebound hypercalcaemia. All patients achieved stability of the spine and resolution of neurological impairment, if present. Six patients achieved metabolic remission and have ceased denosumab without recurrence to date; the other showed clinical and radiological improvement without complete metabolic remission. Three patients developed symptomatic hypercalcaemia 5-7 months after cessation of denosumab, requiring additional bisphosphonate treatment. We present our algorithm for the surgical and medical management of paediatric spinal ABC. Denosumab produced a radiological and metabolic response in all patients, with complete remission in most. Follow-up time was not long enough to evaluate the endurance of response after cessation in some patients. Incidence of rebound hypercalcaemia in this paediatric cohort was high, prompting a change to our protocol.

The role of neoadjuvant denosumab in the treatment of aneurysmal bone cysts: a case series and review of the literature

OBJECTIVE

Aneurysmal bone cysts (ABCs) are benign cystic lesions most commonly occurring in the long bones of pediatric patients. Spinal ABCs may be difficult to resect given their invasive, locally destructive nature, proximity to critical structures such as the spinal cord, and their intrinsic hypervascularity, for which complete embolization is often constrained by radiculomedullary segmental feeders. Denosumab, a monoclonal antibody that binds the receptor activator of nuclear factor kappa B (NF-κB) ligand, has been utilized in the treatment of ABCs most often as a rescue therapy for recurrent disease. Here, the authors present 3 cases of neoadjuvant denosumab use in surgically unresectable tumors to calcify and devascularize the lesions, allowing for safer, more complete resection.

METHODS

This is a single-center, retrospective case series treated at a tertiary care cancer center. The authors present 3 cases of spinal ABC treated with neoadjuvant denosumab.

RESULTS

All 3 patients experienced calcification, size reduction, and a significant decrease in the vascularity of their ABCs on denosumab therapy. None of the patients developed new neurological deficits while on denosumab. Subsequently, all underwent resection. One patient continued denosumab during the immediate postoperative period because a subtotal resection had been performed, with stabilization of the residual disease. No complications were associated with denosumab administration.

CONCLUSIONS

The use of denosumab in unresectable ABCs can cause calcification and devascularization, making safe resection more likely.

Aneurysmal bone cyst and osteoblastoma after neoadjuvant denosumab: histologic spectrum and potential diagnostic pitfalls

The use of denosumab to treat giant cell tumors of bone (GCT) and other giant cell-containing bone tumors has become more common. While the clinicopathologic features of denosumab-treated giant cell tumors of bone have been well-illustrated, descriptions of other denosumab-treated bone tumors are very limited. Surgical pathology files of two institutions and consultation files from two authors were searched for denosumab-treated aneurysmal bone cysts and denosumab-treated osteoblastomas. Clinicopathologic features were reviewed and analyzed. We identified four patients with denosumab-treated bone tumors other than GCT from our surgical pathology and consultation files, including two aneurysmal bone cysts and two osteoblastomas. All were treated with denosumab for 0.5-7.0 (median 4.5) months. Radiologically, denosumab-treated tumors showed decreased size with increased ossification and mineralization on CT and heterogeneous intermediate to hypointense signal on MRI. Histologically, denosumab-treated aneurysmal bone cyst contained thin, elongated, curvilinear, and anastomosing strands of bone with empty lacunae, while denosumab-treated osteoblastoma showed circumscribed nodules of woven bone lined by small osteoblasts. Denosumab-treated aneurysmal bone cyst and osteoblastoma showed treatment-related morphologic changes that can mimic other bone neoplasms. Their recognition requires correlation with the clinical history of denosumab use and radiologic findings.

Doxycycline sclerotherapy of cervical spine aneurysmal bone cysts: single-institution 13-year experience

BACKGROUND

Aneurysmal bone cysts (ABCs) are benign, locally aggressive neoplasms that typically affect patients during their first two decades of life. Curettage with or without bone grafting or adjuvants is the current standard treatment; however, other surgical and medical treatments, such as sclerotherapy, have been reported. Treatment options for cervical spine ABCs are more limited because the proximity of ABCs to critical structures leads to greater risk of spontaneous or treatment-related adverse events, including death.

OBJECTIVE

To retrospectively review all children and young adults with cervical spine ABCs treated with doxycycline sclerotherapy at one referral center to assess its viability as a standalone treatment.

MATERIALS AND METHODS

We retrospectively reviewed the clinical notes and imaging of 16 patients treated with doxycycline sclerotherapy for pathologically proven cervical spine ABCs at our institution between May 2008 and March 2021. All patients underwent image-guided percutaneous doxycycline sclerotherapy to ablate the ABC and stimulate bone formation. We assessed clinical outcomes through chart review and described post-treatment imaging outcomes using modified Neer scoring.

RESULTS

Of the 16 total children and young adults treated, 2 were lost to follow-up, leaving 14 patients with a median age of 14.5 years. Twelve of these 14 patients were successfully treated with doxycycline sclerotherapy for a success rate of 86%. One patient experienced one treatment-related complication (Society of Interventional Radiology [SIR] adverse event classification D), before ultimately being successfully treated. Doxycycline treatment failed in two patients, who then underwent surgical management. Post-treatment imaging of successfully treated cases had a mean modified Neer score of 1.3, whereas post-treatment imaging in failed cases had a mean score of 3.5.

CONCLUSION

Doxycycline sclerotherapy is a viable standalone treatment for cervical spine ABCs because it is safe and effective while avoiding the morbidity associated with open surgical treatments.

Aggressive osteoblastoma with a secondary aneurysmal bone cyst treated with denosumab

Osteoblastomas and aneurysmal bone cysts (ABC) are rare benign bone tumors that make up about 1%-2% of primary bone malignancies, typically occurring in young patients with a median age of 20 years, most commonly effecting the axial skeleton. ABCs may develop independently as primary lesions, or secondary to other bony lesions including osteoblastomas, chondroblastomas, and giant cell tumors. Treatment of unresectable or extensive osteoblastomas can be challenging. In 2013, the Food and Drug Administration (FDA) approved denosumab for the treatment of giant cell tumors of the bone due to its efficacy in these morbid bony lesions. Various case reports have shown that osteoblastomas can respond to denosumab. Furthermore, numerous ABC case reports have described the efficacy of denosumab in these situations. We herein describe a unique case of a young patient with an aggressive osteoblastoma and secondary ABCs who was successfully treated with denosumab.

Denosumab in the management of Aneurysmal bone cyst

BACKGROUND

Aneurysmal bone cyst (ABC) is a benign, locally aggressive tumour that arises predominantly in long bones and spine. Following the encouraging results of denosumab use in Giant Cell Tumors (GCT) and the histological similarities between ABC and GCT, the interest on the role of denosumab in the therapeutic arsenal of the most advanced ABC is growing. The purpose of this literature review is to investigate the current state of knowledge about the use of denosumab in ABCs.

METHODS

A literature research was conducted through PUBMED, COCHRANE and GOOGLE SCHOLAR using the keywords "aneurysmal bone cyst" AND "denosumab". Seventeen articles were included.

RESULTS

A total of 43 cases were reported in the literature. There were 23 males, 20 females. The mean age was 15,9±8,1 year. Pain relief and neurological improvement were rapid and sustained. Radiological assessment showed ossification and/or volume reduction in 36/39 patients. Eight patients (18,6%) presented a recurrence after or during denosumab therapy of whom 7 were adults. Adverse events occurred in 11 patients, 5 of them were admitted to the intensive care unit due to hypercalcemia.

CONCLUSION

Denosumab use in non-surgical ABCs has shown a positive impact in pain and neurological symptoms. The oncological outcome remains unclear with a recurrence rate of 18,6% during/after denosumab therapy, mostly in adults. However, regarding the potential clinical benefits, its use might be discussed in the most advanced cases. Further research and clinical trials are mandatory to precise its belonging in the therapeutic arsenal.

Combined Transarterial Embolization and Percutaneous Sclerotherapy as Treatment for Refractory and Nonresectable Aneurysmal Bone Cysts

PURPOSE

To evaluate the safety and effectiveness of combined transarterial embolization and percutaneous sclerotherapy in the treatment of refractory and nonresectable aneurysmal bone cysts (ABCs) as assessed by imaging and clinical outcomes.

MATERIALS AND METHODS

This retrospective, single-center study included 16 consecutive patients (9 women and 7 men; median age, 17 years [range, 6-25 years]) who underwent combined transarterial embolization (using ethylene vinyl alcohol) and percutaneous sclerotherapy (using ethanol gel and polidocanol) for refractory and nonresectable ABCs. The median follow-up was 27.3 months (range, 6.7-47.5 months). Grade of mineralization (5-point Likert scale), grade of fluid-fluid levels (FFLs; 4-point Likert scale), and contrast-enhancing lesion volume were evaluated before and after treatment. The quality of life was determined before and after treatment using the Musculoskeletal Tumor Society (MSTS) score and the 36-Item Short Form Survey (SF-36) health questionnaire.

RESULTS

A mean of 1.6 ± 0.7 transarterial embolizations and 3.2 ± 1.7 percutaneous sclerotherapies were performed. No adverse events were observed. All patients showed either partial or complete response; no patient showed ABC recurrence. The grade of mineralization (3.7 ± 0.7 after therapy vs 1.4 ± 0.5 at baseline; P < .0001) and grade of FFL (3.5 ± 0.8 after therapy vs 1.9 ± 0.6 at baseline; P < .0001) significantly improved after therapy compared with baseline. The mean contrast-enhancing lesion volume significantly decreased after treatment compared with baseline (45.9 mm³ ± 96.1 vs 156.0 mm³ ± 115.3, respectively; P = .0003). The MSTS scores (28.8 ± 1.8 after treatment vs 14.1 ± 8.6 at baseline; P < .0001) and SF-36 findings revealed a significant improvement in the quality of life after treatment compared with baseline, leaving most patients without relevant constraints.

CONCLUSIONS

Combined transarterial embolization and percutaneous sclerotherapy is a minimally invasive, safe, and effective treatment option for refractory and nonresectable ABCs. Treatment fostered bone mineralization and significantly improved patients' quality of life.

Denosumab Treatment for Giant Cell Tumors, Aneurysmal Bone Cysts, and Fibrous Dysplasia-Risks and Benefits

PURPOSE OF REVIEW

This review summarizes current understanding of the role of denosumab, an inhibitor of receptor activator of nuclear kappa-B ligand (RANKL), in the management of 3 skeletal neoplasms: giant cell tumors, aneurysmal bone cysts, and fibrous dysplasia.

RECENT FINDINGS

A growing body of literature supports denosumab use in giant cell tumors, a neoplasm in which RANKL plays a clear pathogenic role. Comparatively less data is available in aneurysmal bone cysts and fibrous dysplasia; however, the pathogenic similarity of these disorders to giant cell tumors, as well as encouraging preliminary data, suggests denosumab may be useful. Denosumab's inhibitory effects on bone turnover are fully reversible after drug discontinuation. This raises important unanswered questions for clinical management, including potential risks of tumor recurrence and bone turnover rebound. Denosumab is a promising potential treatment for skeletal neoplasms. However, its clinical use is impacted by ongoing safety concerns related to postdiscontinuation rebound, particularly in children. There is a critical need to understand denosumab treatment and discontinuation effects on tumor recurrence and to develop strategies for long-term treatment in patients who cannot be managed surgically.

Chondroblastoma Expresses RANKL by RNA In Situ Hybridization and May Respond to Denosumab Therapy

Lesions of bone featuring osteoclast-like giant cells comprise a diverse group of entities, including giant cell tumor (GCT) of bone, chondroblastoma, and aneurysmal bone cyst, among others. The receptor activator of nuclear factor-κB ligand (RANKL) has been implicated in the pathogenesis of GCT of bone and may play a role in the pathogenesis of other giant cell-rich lesions as well. In addition, RANKL inhibitors (denosumab) have also been shown to have some efficacy in treating some giant cell-rich lesions. Herein, we examine RANKL expression by RNA in situ hybridization in a total of 84 osseous lesions with a focus on chondroblastoma, GCT, fibrous dysplasia, and aneurysmal bone cyst. The lesions were tested for RANKL expression using a chromogenic RNA in situ hybridization assay. RANKL expression was identified in 24/25 (96%) GCT, 24/26 (92%) chondroblastomas, 6/7 (86%) aneurysmal bone cysts, and 3/16 (19%) patients with fibrous dysplasia. RANKL expression was statistically lower in chondroblastoma and aneurysmal bone cyst compared with GCT. RANKL reactivity in fibrous dysplasia was exclusively seen in the 3 cases with osteoclast-type giant cells. Our results indicate a high proportion of chondroblastomas, GCTs, and aneurysmal bone cysts express RANKL while reactivity in fibrous dysplasia is dependent on the presence of osteoclast-type giant cells. On the basis of the success of denosumab therapy for GCTs, our results indicate that it may be a potential therapeutic option in other primary osseous tumors.

Mineral and Bone Consequences of High Dose Denosumab Therapy to Treat an Aneurysmal Bone Cyst, a Child Case Report

Aneurysmal bone cysts (ABCs) are rare benign pseudotumoral bone lesions with potential aggressive behavior due to the extensive destruction of surrounding bone. Traditionally, these tumors were treated with open surgery, but there is more and more a shift to less invasive procedures. In particular, treatment for spinal ABCs is generally unsatisfactory due to the risk of morbidity, neurological impairment and recurrence, and there is a need for innovative therapies. Denosumab has been reported as a useful treatment in giant cell tumors of bone (GCTB), so its efficacy has been tested also in other fibro-osseus lesions affecting children and adolescents, such as spinal aneurysmal bone cysts. The pediatric literature is limited to case reports and small series, all of which highlight the efficacy of this treatment on lesions growth and associated bone pain. Some of these reports have already reported well known side effects associated with denosumab, such as hypocalcemia at the beginning of the treatment, and rebound hypercalcemia at the discontinuation. The latter seems to be more frequent in children and adolescents than in adults, probably due to the higher baseline bone turnover in children. In addition, the use of denosumab in young patients could affect both bone modeling and remodeling, even if the consequences on the growing skeleton have not been reported in detail. Here we describe the case of a spinal ABC diagnosed in an 8-year old young boy which was not accessible to surgery but responded favorably to denosumab. Our aim is to describe the rapid changes in mineral and bone homeostasis in this patient, that required advice from the experts of the European Reference Network (ERN) for rare bone and endocrine diseases.

The Efficacy of Denosumab in the Management of a Tibial Paediatric Aneurysmal Bone Cyst Compromised by Rebound Hypercalcaemia

Surgery is the main treatment option for patients with aneurysmal bone cyst (ABC). We report our experience of using denosumab as an alternative treatment in a child with a multiply recurrent and unresectable tibial ABC. The efficacy and safety of denosumab in the paediatric population, and in the treatment of ABC, are still to be fully evaluated. We describe a 13-year-old boy with an extensive and aggressive ABC involving the proximal tibia, which had recurred following multiple previous surgeries. The patient had ongoing severe pain, was unable to weight-bear, and was at significant risk of pathological fracture. En bloc resection and embolization were not deemed viable, and a decision to use denosumab was made. He received 17 doses of subcutaneous denosumab (70 mg/m²) over a 27-month period, at increasing dose intervals. His symptoms significantly improved, and bony consolidation was observed within six months of treatment. He was able to walk without protection and fully weight-bear without any pain by 18 months. With an increase to a six-month dosing interval, the patient presented with a severe, symptomatic rebound hypercalcaemia requiring bisphosphonate therapy. This reoccurred on two further occasions. This case adds to the evidence that denosumab is effective in the treatment of ABC in paediatric patients, but there is a risk of rebound hypercalcaemia. Therefore, patient awareness and biochemical monitoring for rebound hypercalcaemia are essential.

Challenges of denosumab in giant cell tumor of bone, and other giant cell-rich tumors of bone

Purpose of review

Giant cell tumor of bone (GCTB) is an uncommon benign primary bone tumor, consisting of receptor activator of nuclear factor kappa-B (RANK) expressing reactive osteoclast-like giant cells and neoplastic spindle-shaped cells. Denosumab was approved by FDA in 2013 and by EMA in 2014 to treat adults and skeletally mature adolescents with unresectable GCTB or when resection is likely to result in severe morbidity. However, there is much discussion regarding the optimal applied treatment strategy.

Recent findings

Neoadjuvant treatment of GCTB with denosumab can effectively downstage tumors to facilitate less morbid surgery or completely avoid the need for resection, but there is concern about local recurrence postsurgery. Definitive treatment of unresectable GTCB improves symptoms and halts tumor progression. The optimal treatment duration is unclear and long-term treatment is associated with adverse events like osteonecrosis of the jaw (ONJ) and atypical femoral fractures. Denosumab maintenance dose interval is currently being investigated.

Summary

For the related but heterogenous group of giant cell rich tumors of bone, like aneurysmal bone cysts (ABC) and central giant cell granuloma (CGCG), denosumab is a new treatment modality under investigation. Given the effectiveness in GCTB, this could be a promising treatment option for selected patients with advanced disease.

Off-label uses of denosumab in metabolic bone diseases

Denosumab (Dmab), a monoclonal antibody against the receptor activator of nuclear factor-κB (RANK) ligand (RANKL) which substantially suppresses osteoclast activity, has been approved for the treatment of common metabolic bone diseases, including postmenopausal osteoporosis, male osteoporosis, and glucocorticoid-induced osteoporosis, in which the pathway of the RANK/RANKL/osteoprotegerin is dysregulated. However, the imbalance of RANKL/RANK/osteoprotegerin is also implicated in the pathogenesis of several other rare metabolic bone diseases, including Juvenile Paget disease, fibrous dysplasia, Hajdu Cheney syndrome and Langerhans cell histiocytosis, thus rendering Dmab a potential treatment option for these diseases. Dmab has been also administered off-label in selected patients (e.g., with Paget's disease, osteogenesis imperfecta, aneurysmal bone cysts) due to contraindications or unresponsiveness to standard treatment, such as bisphosphonates. Moreover, Dmab was administered to improve hypercalcemia induced by various diseases, including primary hyperparathyroidism, tuberculosis and immobilization. The aim of this review is to summarize existing evidence on off-label uses of Dmab in metabolic bone diseases and provide opinion for or against its use, which should be always considered on an individual basis.

Image-Guided Percutaneous Management of Skull and Spine Giant Cell Tumors: Case Report of 2 Challenging Cases Successfully Treated with Doxycycline Sclerotherapy

Background

A giant cell tumor (GCT) of bone is a benign, locally aggressive tumor that is often challenging to treat. When complete resection is not possible, curettage with or without adjuvants is the most common treatment. The high frequency of local recurrence and risk of injury to adjacent structures can limit this surgical approach, especially with skull and spine lesions.

Case Description

We report 2 cases of axial skeleton GCTs, 1 in the skull of a 58-year-old woman in whom operative management failed, who experienced local recurrence, and 1 in the cervical spine of an 8-year-old girl that grew extracompartmentally to surround her brachial plexus. Both patients were referred to us because of the surgically challenging nature of their tumors. After completion of the same percutaneous doxycycline sclerotherapy protocol previously described for aneurysmal bone cysts (ABCs), both patients were considered cured and were able to return to normal activities without loss of pretreatment function. After 4 and 10 years of follow-up, respectively, there has been no tumor recurrence in either patient.

Conclusions

We successfully treated 2 patients with very challenging axial skeleton GCTs using a percutaneous doxycycline sclerotherapy protocol previously shown to have success with ABCs. We believe that this minimally invasive procedure should be considered a potential alternative treatment for GCTs, especially axial skeleton lesions, which may not be easily approached with standard surgical techniques.

Aneurysmal bone cyst: results of an off label treatment with Denosumab

Background

The treatment of aneurysmal bone cysts (ABCs) has evolved and less invasive methods have been tried. Denosumab is a monoclonal antibody which inhibits osteoclasts. It has been shown to be effective in giant cell tumour of bone (GCT) of bone and hence promises some effect also in ABC. We report on 6 patients treated with Denosumab and compare our results to the cases already published.

Methods

Data of 6 patients with ABCs and patients whose treatment included Denosumab were retrospectively analyzed. Denosumab was used at a dose of 120 mg on days 1, 8, 15 and 29, and every 4 weeks thereafter. In some of these patients the dose was reduced at the end of the treatment. Clinical and radiological responses were evaluated.

Results

In 4 female and 2 male patients with a mean age of 17 years (range: 6–30 years) the lesions were located in the sacrum (2), in distal radius, distal femur, talus and pelvis. One of the sacral lesions healed after 12 months and has stayed stable for 3 years since. The second patient received 2 years of therapy with recalcification, but recurred 1 year later and is under renewed therapy. The pelvic lesion improved but recurred. This patient has a 13-years history of intermittent therapy including surgery, two pregnancies and remains in a stable situation. The lesion of the talus did not improve with Denosumab after surgery and was complicated by destruction of the ankle joint with osteoarthritis. Recurrent lesions of the distal femur and the distal radius, previously treated by curettage and bone grafting healed under Denosumab and have remained stable for 2 and 3 years, respectively. One case of severe hypercalcemia was observed in a 7-year old child 6 months after discontinuation of Denosumab.

Conclusion

Denosumab provides a treatment option for ABCs in anatomically critical locations. Adjuvant application might reduce the rate of local recurrence. In young patients, severe rebound hypercalcemia months after discontinuation of Denosumab may occur.

Use of Denosumab in Children With Osteoclast Bone Dysplasias: Report of Three Cases

Denosumab has been used successfully to treat disease‐associated osteoclast overactivity, including giant cell tumor of bone. Given its mechanism of action, denosumab is a potent potential treatment of other osteoclast bone dysplasias including central giant cell granuloma (CGCG), aneurysmal bone cyst (ABC), and cherubism. Relatively little is known about the safety and efficacy of denosumab in patients with these conditions, especially in children. We report on 3 pediatric patients treated with denosumab over a 3‐year period at UCLA Medical Center (Los Angeles and Santa Monica, CA, USA): a 12‐year‐old with recurrent ABC of the pelvis, a 14‐year‐old with CGCG of the mandible, and a 12‐year‐old with cherubism. All were started on a 1‐year course of 15 doses 120 mg s.c., given monthly with two loading doses on day 8 and 15. All patients demonstrated rapid and pronounced clinical improvement while on denosumab, including a significant reduction in pain and sclerosis of lytic lesions on radiographs. Within 1 month of initiating therapy, 2 patients experienced hypocalcemia (Common Terminology Criteria for Adverse Events [CTCAE] grade 2) and hypophosphatemia, with 1 patient experiencing symptoms. One patient went on to experience symptomatic rebound hypercalcemia (CTCAE grade 4) 5 months after completing therapy, requiring bisphosphonates and calcitonin. For the second patient, we developed a schedule to wean denosumab involving the progressive lengthening of time between doses from 1 to 4 months in 1‐month increments before cessation. We found that denosumab therapy results in significant clinical and radiographic improvement for pediatric patients with nonresectable ABC, CGCG, and cherubism. Problems with serum calcium may be more common in younger patients, with symptomatic and protracted rebound hypercalcemia after cessation of therapy the most significant. We present a potential solution to this problem with progressive spacing of doses. Potential serious adverse events from alterations in calcium homeostasis should be explored in prospective clinical trials. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Expression Profiling of Receptor-Activator of Nuclear Factor-Kappa B Ligand in Soft Tissue Tumors

Bone and soft tissue tumors are derived from mesenchymal cells, and they are hard to treat. Receptor-activator of nuclear factor-kappa B ligand (RANKL) is an essential cytokine for osteoclast differentiation and activation and is expressed on the surface of osteoblasts or stromal cells. In this study, to explore the potential of denosumab treatment for soft tissue tumors, we analyzed the expression profiles of RANKL mRNA in 425 tumor specimens of 33 histological types by real-time RT-PCR. Denosumab is a monoclonal antibody that prevents the binding of RANKL to receptor-activator of nuclear factor-kappa B (RANK). For comparison, the relative expression levels of RANK and osteoprotegerin (OPG) mRNAs were also measured. OPG functions as a soluble decoy receptor for RANKL. Higher expression levels of RANKL mRNA were detected in calcifying aponeurotic fibroma, fibrosarcoma, calcifying epithelioma, myositis ossificans, heterotopic calcification, giant cell tumor of the tendon sheath (GCTTS), and pigmented villonodular synovitis (PVNS), compared with the levels of other tumor types. Moreover, the expression levels of RANK mRNA were highest in GCTTS, followed by myositis ossificans and PVNS, whereas the expression levels of OPG mRNA were greatly varied among these histological types. We then analyzed RANKL protein expression by immunohistochemistry in 57 tumor specimens with higher expression levels of RANKL mRNA. RANKL-positive cells were detected in GCTTS, PVNS, myositis ossificans, heterotopic calcification, and calcifying aponeurotic fibroma. In conclusion, RANKL is expressed in subsets of soft tissue tumors with calcification, and denosumab is a potential therapeutic option for soft tissue tumors expressing RANKL.

Primary Bone Tumor of the Spine-An Evolving Field: What a General Spine Surgeon Should Know

STUDY DESIGN

A narrative review of the literature.

OBJECTIVE

This article reviews the general principles of treatment and investigation for primary bone tumors of the spine. Furthermore, it explores the emerging alternatives.

METHODS

A review was performed using Medline, Embase, and Cochrane databases.

RESULTS

Primary bone tumors of the spine are rare entities that general spine surgeons may encounter only a few times in their career. The treatment algorithm of these complex tumors is filled with nuances and is evolving constantly. For these reasons, patients should be referred to experienced tertiary or quaternary centers who can offer a comprehensive multidisciplinary approach. For most malignant spinal bone tumors, surgery remains the cornerstone of treatment. Respecting oncologic principles has been associated with improved survival and decreased local recurrence in multiple settings. However, even in experienced centers, these surgeries carry a significant risk of adverse events and possible long-term neurologic impairment. The associated morbidity of these procedures and the challenges of local recurrence have encouraged professionals caring for these patients to explore alternatives or adjuncts to surgical treatment.

CONCLUSIONS

Over the past few years, several advances have occurred in medical oncology, radiation oncology and interventional radiology, changing the treatment paradigm for some tumors. Other advances still need to be refined before being applied in a clinical setting.

Denosumab: A potential new treatment option for recurrent Aneurysmal Bone Cyst of the spine

ABCs are expansile osteolytic lesions typically containing blood-filled spaces separated by fibrous septae. Standard treatment includes surgical resection or curettage and packing; however, for some spinal lesions, the standard approach is not optimal. One therapeutic strategy is to treat spinal ABC with an agent that targets a pathway that is dysregulated in a disease with similar pathophysiology. Denosumab, a human monoclonal antibody to RANKL is effective in the treatment of GCT's. Spinal ABCs are a therapeutic challenge and local recurrence is a concern. We report a case of aggressive recurrent ABC of dorsal spine in a 14-year old female with progressive neurologic deficit who underwent surgical excision and decompression with a recurrence in a short period for which a decompression and fixation was done. She had a recurrence after an asymptomatic period of 6 months and neurologic worsening. Having ruled out use of embolization and radiotherapy, a remission was achieved by treatment with Denosumab using the regimen for GCTs for a duration of 6 months. Follow-up MRI and CT scans at 24 months following inception of Denosumab depicted complete resolution and no recurrence. We conclude that Denosumab can result in symptomatic and radiological improvement in the recurrent locally aggressive ABC and may be useful in selected cases. Long-term results are mandatory to confirm the efficacy of Denosumab and to evaluate local recurrence after stopping Denosumab.

Denosumab Therapy in the Management of Aneurysmal Bone Cysts: A Comprehensive Literature Review

Aneurysmal bone cysts (ABCs) are uncommon lesions that involve the axial and appendicular bones. Although biologically benign, ABCs have the tendency to assume an aggressive behavior causing local destruction of the underlying bone and neighboring soft tissues. Morphologically, ABCs are composed of cyst-like cavities filled with blood and bounded by an array of diverse cells including fibroblasts, inflammatory infiltrates and osteoclast-like multinucleated giant cells. From a molecular perspective, the osteoclast-like multinucleated giant cells harbor high expression of receptor activator of nuclear factor kappa B (RANK) receptors, whereas the neoplastic stromal cells harbor high expression of RANK ligand (RANKL). The RANK-RANKL interaction has been implicated in the carcinogenesis of ABCs and giant cell tumor of bones (GCTBs). Currently, the optimal management of ABCs remains a hotly debated topic. There are a multitude of treatment modalities (that is, surgery, sclerotherapy, radiotherapy and selective arterial embolization), and each modality has its own benefits, morbidity and risk of complications. The local aggressiveness of ABC and its high rates of relapse following treatment has demanded the march towards discovering more innovative therapies. One of such therapies is denosumab, a monoclonal antibody targeted against the RANKL. Denosumab is already approved by the United States Food and Drug Administration (FDA) for the treatment of adults and skeletally mature adolescents with GCTB that is unamenable to surgery, or initial surgery is anticipated to result in significant morbidity. However, denosumab is not approved by the FDA for the management of ABCs. However, taking into consideration the morphological similarity between GCTBs and ABCs, some treating physicians have logically opted to use denosumab in an off-label manner to treat select ABCs. To the best of knowledge, no study has attempted to summarize the related literature on the use of denosumab in ABCs. Therefore, the primary aim of this study is to narratively review all the available literature about the efficacy and safety of the use of off-label denosumab in the management of patients with ABCs.

Recurrent Aneurysmal Bone Cyst of the Distal Fibula Treated with Denosumab and Curettage

We report the case of a 13-year-old girl with multiple recurrences of an aneurysmal bone cyst of the distal fibula successfully treated with denosumab and curettage. Aneurysmal bone cysts are locally aggressive lesions with high rates of recurrence. The novel use of denosumab with curettage in a long bone showed a favorable outcome with no adverse events or signs of recurrence three years after treatment.

PERCUTANEOUS TREATMENT OF ANEURYSMAL BONE CYST WITH CALCITONIN AND METHYLPREDNISOLONE

OBJECTIVE

To introduce the intralesional calcitonin and methylprednisolone percutaneous injection method, which results in the promotion of primary aneurysmal bone cyst (ABC) healing.

METHODS

A retrospective cohort study involving 76 patients diagnosed with ABC was performed between 2005 and 2014. Patients treated with calcitonin and methylprednisolone injection and who underwent more than 2 years of follow-up were considered eligible for the study (n=47). The Enneking staging and Capanna classification systems were used during the initial evaluation. Treatment response was assessed by Rastogi radiographic grading based on the degree of healing. X² and Wilcoxon signed-rank tests and odds ratio calculations were used in the statistical analysis with a 5% significance level.

RESULTS

The proximal tibia extremity was the most commonly affected site (17.0%). Thirty-three (70.3%) ABC cases were staged as B3 and 28 (59.7%) were classified as type II. The average number of injections performed was 2.8 per patient, with an average reduction of the initial lytic area of 83.7% (p-value=0.00001). Satisfactory results for 91.4% (n=43; p-value=0.00001) were obtained and 5 recurrences occurred. No side effects were observed.

CONCLUSION

Intralesional calcitonin and methylprednisolone percutaneous injection is a minimally invasive, effective, and safe method for promoting primary ABC healing. Level of evidence IV, Type of study: case series.

The Changing Sensory and Sympathetic Innervation of the Young, Adult and Aging Mouse Femur

Although bone is continually being remodeled and ultimately declines with aging, little is known whether similar changes occur in the sensory and sympathetic nerve fibers that innervate bone. Here, immunohistochemistry and confocal microscopy were used to examine changes in the sensory and sympathetic nerve fibers that innervate the young (10 days post-partum), adult (3 months) and aging (24 months) C57Bl/6 mouse femur. In all three ages examined, the periosteum was the most densely innervated bone compartment. With aging, the total number of sensory and sympathetic nerve fibers clearly declines as the cambium layer of the periosteum dramatically thins. Yet even in the aging femur, there remains a dense sensory and sympathetic innervation of the periosteum. In cortical bone, sensory and sympathetic nerve fibers are largely confined to vascularized Haversian canals and while there is no significant decline in the density of sensory fibers, there was a 75% reduction in sympathetic nerve fibers in the aging vs. adult cortical bone. In contrast, in the bone marrow the overall density/unit area of both sensory and sympathetic nerve fibers appeared to remain largely unchanged across the lifespan. The preferential preservation of sensory nerve fibers suggests that even as bone itself undergoes a marked decline with age, the nociceptors that detect injury and signal skeletal pain remain relatively intact.

Denosumab in patients with aneurysmal bone cysts: A case series with preliminary results

Purpose:

Aneurysmal bone cyst (ABC) is a rare skeletal tumor usually treated with surgery/embolization. We hypothesized that owing to similarities with giant cell tumor of bone (GCTB), denosumab was active also in ABC.

Methods:

In this observational study, a retrospective analysis of ABC patients treated with denosumab was performed. Patients underwent radiologic disease assessment every 3 months. Symptoms and adverse events were noted.

Results:

Nine patients were identified (6 male, 3 female), with a median age of 17 years (range 14–42 years). Primary sites were 6 spine–pelvis, 1 ulna, 1 tibia, and 1 humerus. Patients were followed for a median time of 23 months (range 3–55 months). Patients received a median of 8 denosumab administrations (range 3–61). All symptomatic patients had pain relief and 1 had paresthesia improvement. Signs of denosumab activity were observed after 3 to 6 months of administration: bone formation by computed tomography scan was demonstrated in all patients and magnetic resonance imaging gadolinium contrast media decrease was observed in 7/9 patients. Adverse events were negligible. At last follow-up, all patients were progression-free: 5 still on denosumab treatment, 2 off denosumab were disease-free 11 and 17 months after surgery, and the last 2 patients reported no progression 12 and 24 months after denosumab interruption and no surgery.

Conclusions:

Denosumab has substantial activity in ABCs, with favorable toxicity profile. We strongly support the use of surgery and/or embolization for the treatment of ABC, but denosumab could have a role as a therapeutic option in patients with uncontrollable, locally destructive, or recurrent disease.

Denosumab treatment in aneurysmal bone cyst: Evaluation of nine cases

BACKGROUND

Aneurysmal bone cyst (ABC) is a benign bone tumor. Curettage and bone grafting is the common treatment. Here, we retrospectively evaluate nine patients treated with denosumab.

PROCEDURE

Nine patients with ABC, mostly pelvic and vertebral, treated with denosumab were analyzed retrospectively. A 70 mg/m² denosumab dose was used weekly in the first month, and then monthly. Clinical and radiological responses to treatment were evaluated.

RESULTS

In all patients, clinical symptoms including pain and limping regressed completely within 3 months. Radiological evaluation revealed changes in lesion size and content. In six patients, overall volume reduction in the range of 18-82% was detected. Decreases in the size and number of cysts were detected in eight patients. In five patients, fat signal appeared on follow-up imaging. No major side effects were observed during treatment. Median follow-up time after treatment was 15 months. At 5 months, severe hypercalcemia was observed in two patients due to rebound increase in osteoclastic activity. Subsequent to denosumab treatment, three patients underwent surgery for clinical or radiological recurrence.

CONCLUSIONS

Our results showed that denosumab provided a meaningful clinical and radiological improvement in ABC. It may be a treatment option, especially in spinal and pelvic tumors with potentially high surgical morbidity. However, late rebound hypercalcemia may restrict its use. Studies with more cases are required for routine use of denosumab in ABC.

Denosumab: a potential treatment option for aneurysmal bone cyst of the atlas

PURPOSE

Aneurysmal bone cysts (ABCs) of spine are conventionally treated with en-bloc resection or intralesional excision/curettage and reconstruction or filling of defects with bone cement. For the treatment of upper cervical ABCs, en-bloc resections are often not desirable considering the risk/benefit ratio while the risk of recurrence after intralesional excision is high. Hence, alternative management options are often necessary. We describe our clinical experience with one such treatment alternative-denosumab for the treatment of ABC of Atlas.

METHODS AND RESULTS

We present a case of 16-year-old boy who presented with neck pain and restriction of neck movements. A large lytic lesion with multiple fluid-fluid interfaces involving vertebral arch of atlas was identified on further imaging. There was destruction of right lateral mass and the lesion was found encasing the right vertebral artery. Core needle biopsy confirmed the diagnosis of ABC. With no visible CT response after first session of intra-lesional injection of Calcitonin and Methylprednisolone, the patient was treated with denosumab (120 mg SC once-a-month) for a period of 12 months. His symptoms resolved within 7 months of onset of treatment and serial CT scans over 12-month treatment period showed complete ossification of the lesion. Further there was no evidence of recurrence at 12 months after completion of treatment.

CONCLUSION

Our case report contributes to the accruing evidence on the effectiveness of denosumab for the treatment of spinal ABCs. However, long-term safety, risk of recurrence, optimal duration of treatment and consistency of denosumab are yet to be determined.

Denosumab as a potential therapeutic option for leiomyosarcoma with osteoclast-like giant cells: A case report

Bone leiomyosarcoma is a rare primary osseous malignant tumor with a high metastatic potential. Similar to other bone sarcomas, high histological grade and tumor stage are predictive of a poor outcome. We herein present our experience with treating a 64-year-old woman with bone leiomyosarcoma accompanied by multiple bone metastases. A biopsy revealed occasional osteoclast-like giant cells. In addition to radiation therapy, the osteoclastogenesis inhibitor denosumab was administered but the patient did not undergo adjuvant chemotherapy or surgery. Good clinical and short-term radiological responses to denosumab have been observed for 2 years. Therefore, denosumab may represent a viable treatment option without the need for adjuvant chemotherapy.

Monoclonal antibodies for treating osteoporosis

INTRODUCTION

Osteoporosis is the most widespread skeletal disease requiring innovative therapeutic strategies for its management. The understanding of receptor activator of nuclear factor kappa-B ligand (RANKL) and sclerostin's role in bone cell biology is completely changing the therapeutic landscape. RANKL supports osteoclast formation and activity and is mainly produced by cells of osteoblastic lineage. Sclerostin, an antagonist of the Wnt pathway, has a key role in bone formation and is mainly secreted by osteocytes. High levels of RANKL and sclerostin have been detected in osteoporosis, leading to the production of antibodies able to neutralize their activity.

AREAS COVERED

In this review, the authors give an overview and discuss the literature and data on denosumab and romosozumab to treat osteoporosis. Clinical studies indicate that long-term treatment with denosumab causes a continuous increase in bone mineral density with low incidence of adverse effects. Romosozumab treatment gives increases bone formation and improves bone mineral density (BMD) though further studies are needed to better evaluate the adverse effects.

EXPERT OPINION

Denosumab and romosozumab show promise in the treatment of osteoporosis. Furthermore, their different mechanisms of action compared to existing anti-osteoporotic drugs may permit alternative strategies for osteoporosis treatment down the line

Therapeutic Management of a Substantial Pelvic Aneurysmatic Bone Cyst Including the Off-Label Use of Denosumab in a 35-Year-Old Female Patient

Aneurysmal bone cysts (ABC) are benign bone tumors, which are highly vascularized. The main course of treatment is curettage followed by bone grafting or cement insertion. Still recurrence remains a main problem for patients. Denosumab is a monoclonal antibody, which acts as an inhibitor of the RANK/RANKL pathway, diminishing bone turnover. Recent case reports have shown that Denosumab can be a promising therapeutic agent for people suffering from therapy-resistant ABC. We report the case of a 35-year-old female patient presenting with a pronounced ABC of the pelvis. Since the tumor was inoperable, Denosumab was administered, leading to a significant shrinkage of the lesion, which allowed surgical intervention. Upon recurrence, Denosumab was restarted putting the patient once more into remission. Follow-up was four years overall with a clinical and radiological stable disease for fifteen months after final discontinuation of the monoclonal antibody. Therefore, our case further underlines the potential of Denosumab in the treatment of ABC.

Denosumab: an Emerging Therapy in Pediatric Bone Disorders

PURPOSE OF REVIEW

Denosumab is an inhibitor of receptor activator of nuclear factor kappa-B ligand (RANKL), and has emerged as an important novel therapy for skeletal disorders. This article examines the use of denosumab in children.

RECENT FINDINGS

Considerable safety and efficacy data exists for denosumab treatment of adults with osteoporosis, bone metastases, and giant cell tumors. Pediatric data is limited; however, evidence suggests denosumab may be beneficial in decreasing bone turnover, increasing bone density, and preventing growth of certain skeletal neoplasms in children. Denosumab's effect on bone turnover is rapidly reversible after drug discontinuation, representing a key difference from bisphosphonates. Rebound increased bone turnover has led to severe hypercalcemia in several pediatric patients. Denosumab is a promising therapy for pediatric skeletal disorders. At present, safety concerns related to rebounding bone turnover and mineral homeostasis impact use of denosumab in children. Research is needed to determine if and how these effects can be mitigated.

Efficacy and Safety of Selective Arterial Embolization in the Treatment of Aneurysmal Bone Cyst of the Mobile Spine: A Retrospective Observational Study

STUDY DESIGN

A retrospective observational study.

OBJECTIVE

Our aim is to define the efficacy and safety of serial selective arterial embolization (SAE) in the treatment of aneurysmal bone cysts (ABCs), to explore potential treatment alternatives, and to define a therapeutic algorithm.

SUMMARY OF BACKGROUND DATA

ABC is a benign lesion with an unpredictable behavior. Its treatment is challenging especially in poorly accessible surgical areas, such as spine and pelvis. Currently, the first-line treatment of ABC is repeated SAE until healing. Other options have been used with variable success rates.

METHODS

From January 2004 to September 2015, 23 patients affected by ABC of the mobile spine have been treated with SAE and prospectively followed up by computed tomographic scan and magnetic resonance imaging. Signs of neurological deficit, complications, healing of the lesion, and clinical outcomes were registered.Signs of healing are defined as peripheral sclerotic bone rim formation, decrease of the ABC mass, disappearance of the double content image, and bone formation inside the ABC mass, associated with remission of pain.

RESULTS

Twenty-three patients underwent SAE according to the protocol. Seventeen patients have healed. The number of procedures necessary to obtain healing (clinical and radiographic) varied from 1 to 10. No complication occurred during the procedure. Follow-up time ranged from 5 to 120 months after the last angiographic procedure. All 17 patients had complete relief of pain symptoms. Six patients did not respond to SAE, presenting a progressive clinical and radiographic worsening, and underwent other medical or minimally invasive treatments.

CONCLUSION

Our study confirms the safety of SAE. The efficacy of the treatment was however lower than expected. SAE is indicated when pathological fracture or signs of cord damage are not detected. Infiltration with autologous bone marrow concentrate or administration of Denosumab is under investigation as alternative choices of treatment.

LEVEL OF EVIDENCE

4.

En Bloc Resections in the Spine: The Experience of 220 Patients During 25 Years

BACKGROUND AND OBJECTIVE

En bloc resections aim at surgically removing a tumor in a single, intact piece. Approach must be planned for the complete removal of the tumor without violation of its margins. The shared knowledge of the morbidity, mortality, risk assessment for local disease recurrence, complications, and death, related to spine tumors excised en bloc could improve the treating physician's apprehension of the diseases and decision making process before, during, and after surgical treatment. The purpose of this study was to review and report the experience gained during 25 years in one of the world's biggest spine oncologic centers.

METHODS

A retrospective study of prospective collected data of 1681 patients affected by spine tumors, of whom 220 had en bloc resections performed.

RESULTS

Most tumors were primary-165 cases (43 benign and 122 malignant); metastases occurred in 55 patients. A total of 60 patients died from the disease and 33 local recurrences were recorded. A total of 153 complications were observed in 100 of 216 patients (46.2%); 64 of these patients (30%) suffered 1 complication, whereas the rest had 2 or more. All complications were categorized according to temporal distribution and severity. These were further divided into 7 groups according to the type of complication. There were 105 major and 48 minor complications. Seven patients (4.6%) died as a result of complications. There were 33 local recurrences (15.28%) recorded. Contaminated cases, surgical margins of the resected tumor-intralesional, marginal, and malignant tumors-were statistically significant independent risk factors for local recurrence of the tumor. Contamination, local recurrence, neoadjuvant radiotherapy, number of levels resected, and metastatic tumors compared with primary malignant tumor were shown to be independent risk factors for a patient's death.

CONCLUSIONS

Treatment of spinal aggressive benign and malignant bone tumors with en bloc resection is beneficial in terms of better local control and prognosis, although it is a highly demanding and risky procedure. Margins are the key point of this procedure, thus a careful preoperative oncologic and surgical staging is necessary to define the optimal surgical approach. The adverse event profile of these surgeries is high. Therefore, it should be performed by experienced and multidisciplinary teams in specialized high volume centers.

Current management of aneurysmal bone cysts

Aneurysmal bone cysts (ABCs) are benign bone lesions arising predominantly in the pediatric population that can cause local pain, swelling, and pathologic fracture. Primary lesions, which constitute roughly two thirds of all ABCs, are thought to be neoplastic in nature, with one third of ABCs arising secondary to other tumors. Diagnosis is made with various imaging modalities, which exhibit characteristic features such as "fluid-fluid levels," although biopsy is critical, as telangiectatic osteosarcoma cannot be excluded based on imaging alone. Currently, the standard of care and most widely employed treatment is intralesional curettage. However, tumor recurrence with curettage alone is common and has driven some to propose a multitude of adjuvants with varying efficacy and risk profiles. Historically, therapies such as en bloc resection or radiation therapy were utilized as an alternative to decrease the recurrence rate, but these therapies imposed high morbidity. As a result, modern techniques now seek to simultaneously reduce morbidity and recurrence, the pursuit of which has produced preliminary study into minimally invasive percutaneous treatments and medical management.

Benign Tumors of the Spine: Has New Chemotherapy and Interventional Radiology Changed the Treatment Paradigm?

STUDY DESIGN

Clinically based systematic review.

OBJECTIVE

To determine the role of (A) medical treatment and (B) interventional radiology as either adjuvant or stand-alone treatment in primary benign bone tumors of the spine.

METHODS

A multidisciplinary panel of spine surgeons, radiation oncologists, and medical oncologists elaborated specific focused questions regarding aneurysmal bone cyst, giant cell tumor, and osteoid osteoma. Denosumab, bisphosphonate, interferon, bone marrow aspirate, doxycycline, thermal ablation, and selective arterial embolization were identified as areas of interest for the article. A systematic review was performed through MEDLINE and EMBASE. Recommendations based on the literature review and clinical expertise were issued using the GRADE system.

RESULTS

The overall quality of the literature is very low with few multicenter prospective studies. For giant cell tumor, combination with Denosumab identified 14 pertinent articles with four multicenter prospective studies. Nine studies were found on bisphosphonates and six for selective arterial embolization. The search on aneurysmal bone cyst and selective arterial embolization revealed 12 articles. Combination with Denosumab, Doxycycline, and bone marrow aspirate identified four, two, and three relevant articles respectively. Eleven focused articles were selected on the role of thermal ablation in osteoid osteoma.

CONCLUSION

Alternative and adjuvant therapy for primary benign bone tumors have emerged. Their ability to complement or replace surgery is now being scrutinized and they may impact significantly the algorithm of treatment of these tumors. Most of the data are still emerging and further research is desirable. Close collaboration between the different specialists managing these pathologies is crucial.

LEVEL OF EVIDENCE

N/A.

Receptor-Activator of Nuclear KappaB Ligand Expression as a New Therapeutic Target in Primary Bone Tumors

The receptor-activator of nuclear kappaB ligand (RANKL) signaling pathway plays an important role in the regulation of bone growth and mediates the formation and activation of osteoclasts. Osteoclasts are involved in significant bone resorption and destruction. Denosumab is a fully human monoclonal antibody against RANKL that specifically inhibits osteoclast differentiation and bone resorption. It has been approved for use for multiple myeloma and bone metastases, as well as for giant cell tumor of bone. However, there is no previous report quantitatively, comparing RANKL expression in histologically varied bone tumors. Therefore, we analyzed the mRNA level of various bone tumors and investigated the possibility of these tumors as a new therapeutic target for denosumab. We examined RANKL mRNA expression in 135 clinical specimens of primary and metastatic bone tumors using real-time PCR. The relative quantification of mRNA expression levels was performed via normalization with RPMI8226, a human multiple myeloma cell line that is recognized to express RANKL. Of 135 cases, 64 were also evaluated for RANKL expression by using immunohistochemistry. Among all of the tumors investigated, RANKL expression and the RANKL/osteoprotegerin ratio were highest in giant cell tumor of bone. High RANKL mRNA expression was observed in cases of aneurysmal bone cyst, fibrous dysplasia, osteosarcoma, chondrosarcoma, and enchondroma, as compared to cases of multiple myeloma and bone lesions from metastatic carcinoma. RANKL-positive stromal cells were detected in six cases: five cases of GCTB and one case of fibrous dysplasia. The current study findings indicate that some primary bone tumors present new therapeutic targets for denosumab, particularly those tumors expressing RANKL and those involving bone resorption by osteoclasts.

Response of Aneurysmal Bone Cyst to Denosumab

STUDY DESIGN

Case report and literature review.

OBJECTIVE

To describe a unique case of large sacral aneurysmal bone cysts (ABCs) treated with denosumab and review the literature on this rare entity.

SUMMARY AND BACKGROUND DATA

ABCs are expansile osteolytic lesions that typically contain blood-filled spaces separated by fibrous septa. Standard treatment includes surgical resection or curettage and packing; however, for some spinal lesions, the standard approach is not optimal. One therapeutic strategy is to treat spinal ABC with an agent that targets a pathway that is dysregulated in a disease with similar pathophysiology. The bone destruction in both giant cell tumors of bone and ABCs is mediated by RANK ligand (RANKL) produced by the tumor cells. Denosumab, a human monoclonal antibody to RANKL, is effective in the treatment of giant cell tumors of bone.

METHODS

We report a case of a large sacral ABC that responded to denosumab. A 27-year-old male developed increasing back pain. Imaging revealed a lytic lesion in the sacrum with no clear solid component and regions where the cortex was difficult to identify. ABC was diagnosed on biopsy. Surgery or radiation treatment was expected to be associated with serious morbidity; therefore, denosumab was given using the regimen for giant cell tumors of bone (120  mg monthly with a loading dose).

RESULTS

The patient's pain gradually resolved after 2 months of treatment. New bone formation with a more clearly defined cortex was evident on computed tomographic scan at 16 weeks and continued to show evidence of improvement at 7 and 12 months. Biopsy at 12 months revealed a hypocellular fibrous stroma with new bone formation and no giant cells.

CONCLUSION

We conclude that denosumab can result in symptomatic and radiological improvement in ABC and may be useful in select cases.

LEVEL OF EVIDENCE

5.

Treatment Challenges with Benign Bone Tumors of the Orbit

Benign mesenchymal tumors of the craniofacial complex present unique challenges for orbital surgeons because of their potential for orbital compartment syndrome, ocular morbidity, and facial disfigurement and because definitive surgical management may be associated with significant morbidity. While the precise classification of such lesions depends on radiologic as well as histologic evaluations and remains controversial, benign tumors involving the bony walls of the orbit share features of bony expansion, facial deformity, and the potential to cause significant orbital and ophthalmic morbidity. We herein present 2 cases of benign mesenchymal tumors with bony involvement in the orbitofacial region (1 juvenile ossifying fibroma and 1 central giant cell granuloma) and review the current management of similar benign fibro-osseous and reactive bone lesions of the orbit. These rare entities presented share common orbital and ophthalmic manifestations and remain without any effective definitive treatment options.

[New surgical treatment options for bone tumors]

Primary bone neoplasms can be classified into benign, locally/aggressive and rarely metastasizing and malignant tumors. Patients with benign tumors usually undergo surgical treatment in cases of local symptoms, mainly consisting of pain or functional deficits due to compression of important anatomical structures, such as nerves or blood vessels. Locally/aggressive and rarely metastasizing tumors exhibit an infiltrative growth pattern, so that surgical treatment is necessary to prevent further destruction of bone leading to local instability. Finally, the surgical treatment of malignant tumors is, with few exceptions, considered to be a prerequisite for long-term survival, either alone or in combination with systemic chemotherapy. Whereas the main objective of surgery in the treatment of benign tumors is relief of local symptoms with a minimum amount of damage to healthy tissue and minimizing the risk of local recurrence while ensuring bone stability in locally aggressive and rarely metastasizing tumors, the primary goal in the operative treatment of bone sarcomas is the resection of the tumor with clear surgical margins followed by defect reconstruction and the preservation of function. This review examines the current developments in the surgical treatment of primary bone neoplasms with respect to the management of the tumors and novel reconstructive options.