Outcomes of Non-vascularized Fibular Grafts in Proximal Humerus Aneurysmal Bone Cysts.

Introduction This study focuses on the management of primary aneurysmal bone cysts (ABCs) through comprehensive curettage, hydrogen peroxide lavage, and non-vascularized strut fibular grafting. Methods The research encompassed 20 cases, predominantly males (80%), with an average age of 11.35 years. Patient assessment involved thorough history-taking, clinical examinations, and radiological evaluations, including plain radiographs, CT scans, and MRI. The study evaluated healing, bone consolidation, and complications, with patients assessed using the Musculoskeletal Tumor Society (MSTS) upper limb score. Results and discussion The results demonstrated a mean MSTS score of 91.55%, indicating favorable outcomes compared to prior studies. The utilization of non-vascularized autogenous fibular grafts offered effective mechanical stabilization and facilitated an early return to normal function, even prior to complete cavity filling. Our research underscores the efficacy of this treatment approach for primary ABC, particularly in achieving satisfactory functional outcomes. Moreover, the findings contribute to the understanding of optimal management strategies for ABC, considering factors such as patient age, lesion location, vascularity, and size. Conclusion The study advocates for the adoption of thorough curettage, hydrogen peroxide lavage, and non-vascularized strut fibular grafting as a reliable treatment modality for primary ABC. This approach highlights its potential to enhance patient outcomes and functional recovery.

Aggressive Giant Extraskeletal Aneurysmal Bone Cyst of the Thigh: Overcoming Challenges with a Multidisciplinary Approach.

Aneurysmal bone cysts are vascular benign fibroblastic lesions usually found in bone that are locally destructive, with a greater incidence in the first and second decades of life. Patients usually undergo curettage or, less frequently, surgical resection, which may lead to growth disturbances and deformities in cases of large or complex lesions. Minimally invasive techniques such as sclerotherapy and endovascular embolization have been developed as an alternative or complement to surgery, with promising results. The authors present a rare case of an extraskeletal aneurysmal bone cyst successfully treated with minimally invasive techniques followed by surgical resection and provide a literature review of the current treatment options.

Denosumab Re-Challenge and Long-Term Efficacy for Aneurysmal Bone Cyst of the Spine: Enhanced Treatment Algorithm.

Background/Objective: Surgical treatment of aneurysmal bone cysts (ABCs) can be challenging, especially in the spine. Non-surgical treatments such as with denosumab have shown promising results in different osteolytic pathologies. This retrospective observational study aimed to evaluate the long-term clinical and radiologic response of patients with ABCs of the mobile spine treated with denosumab and propose an updated treatment algorithm. Methods: Six patients with relapsed and symptomatic ABCs of the mobile spine were treated with denosumab (120 mg subcutaneously on days 1, 8, 15, 29, and every 4 weeks thereafter) between 2012 and 2023. Disease assessments were conducted using CT and MRI at 3, 6, 9, and 12 months post-treatment. Clinical data, including pain levels, symptoms, and adverse events, were documented from patients' charts. Results: Patients underwent an initial phase of treatment with denosumab, receiving a mean of 22 administrations (range 13-42) over a median follow-up period of 41 months (range 15-98 months). Clinical improvement was observed in all patients after 4 weeks of treatment, and all patients demonstrated a radiological response after 12-24 weeks on denosumab. Three patients were progression-free after discontinuing denosumab following 13, 15, and 42 administrations, respectively. At the last follow-up, after 38, 43, and 98 months, these patients remained stable without relapse of the disease. Three patients had a relapse of disease after denosumab; two of them underwent denosumab re-challenge, while one patient received one mesenchymal stem cells (MSCs) injection. All patients showed clinical and radiological improvement and were resulted to be disease-free at the last follow-up. Conclusions: This study demonstrates the long-term efficacy and safety of denosumab in treating ABCs of the mobile spine, as well as the potential of re-challenge in managing recurrence. A treatment algorithm is proposed, positioning denosumab as a viable therapeutic option after other local treatments. Careful patient selection, monitoring, and further research are necessary to optimize denosumab use for ABCs.

Percutaneous microwave ablation, perfusion, and reconstruction combined with a synthetic bone substitute in symptomatic bone cysts: a minimum of 26 months follow-up.

PURPOSE: The objective was to describe the technique and clinical outcome of microwave thermal ablation (MWA) and perfusion combined with synthetic bone substitutes in treating unicameral bone cysts (UBCs) in adolescents. MATERIALS AND METHODS: A total of 14 consecutive patients were enrolled by percutaneous MWA and saline irrigation combined with synthetic bone substitutes. Clinical follow-up included the assessment of pain, swelling, and functional mobility. Radiological parameters included tumor volume, physis-cyst distance, cortical thickness of the thinnest cortical bone, and the Modified Neer classification system. RESULTS: The mean follow-up was 28.9 months (26-52 months). All UBCs were primary, and all patients underwent the MWA, saline perfusion, and reconstruction combined with a synthetic bone substitute session, except for one patient (7.1%) who required a second session. All patients had good clinical results at the final follow-up. Satisfactory cyst healing was achieved in 13 cases according to radiological parameters. Tumor volume decreased from a mean of 49.7 cm3 before surgery treatment to 13.9 cm3 at the final follow-up (p < 0.01). The physis-cyst distance increased from a mean of 3.17-4.83 cm at the final follow-up (p < 0.01). Cortical thickness improved from a mean of 1.1 mm to 2.0 mm at the final follow-up (p < 0.01). According to the proposed radiological criteria, our results were considered successful (Grading I and II) in 13 patients (92.9%) at the final follow-up. CONCLUSION: Percutaneous microwave ablation combined with a bone graft substitute is a minimally invasive, effective, safe, and cost-effective approach to treating primary bone cysts in the limbs of adolescents.

Aneurysmal bone cyst of the calcaneus: A rare case report and review of the literature.

INTRODUCTION AND IMPORTANCE: Aneurysmal bone cyst (ABC) is a benign lytic bone tumor of the skeletal system but locally destructive lesion of unknown origin. It often occurs in childhood and usually involves the metaphyseal region of long bones; thus, its localisation in the calcaneum remains rare; its atypical presentation in our case makes it remarkable. CASE PRESENTATION: We describe a case of a young patient who suffered from chronic heel pain, in whom the clinical examination finds swelling and pain on palpation. A complete radiological assessment was carried out, which revealed a solitary and expansive osteolytic lesion within the calcaneus. Treatment included tumor curettage and reconstruction with allograft and cement. The biopsy report was consistent with an ABC. The postoperative follow-up at 18 months was marked by a good radio-clinical evolution and no recurrence. CLINICAL DISCUSSION: ABCs are benign cystic expansive tumors that are reactive, locally destructive and blood-filled, their occurrence in the calcaneus has been reported in only 1.6 % of total reported cases. Talalgia is the most frequent sign associated with swelling. Liquid-liquid level images on MRI is a pathognomonic sign of these lesions but the gold standard diagnosis remains histology. Their treatment is based on curettage - filling by grafting. CONCLUSION: Curettage combined graft makes results butter and improves the quality of life.

Acetabular Aneurysmal Bone Cyst During the Syrian Conflict: A Case Report of Surgical Treatment and Outcomes.

Aneurysmal bone cysts (ABCs) are uncommon benign bone lesions that consist of blood-filled vascular spaces surrounded by fibrous tissue septa. Their diagnosis and surgical management are challenging in a war-torn region. In this case report, we present a rare case of a giant aneurysmal bone cyst located around the acetabulum in a 10-year-old female child who presented with an antalgic limp and left hip pain. The lesion was successfully treated with curettage and mixed autologous and synthetic bone grafts, and the follow-up for two years revealed a complete resolution of symptoms and radiological evidence of bone regeneration. This case highlights the successful surgical treatment of a challenging case of ABC in a difficult setting during the Syrian conflict.

Diagnosis and Current Treatment of Aneurysmal Bone Cysts.

The purpose of this review is to increase awareness about the evolution and development of current trends in the diagnosis and treatment of aneurysmal bone cysts (ABCs). ABCs are benign, but locally aggressive bone tumors that mainly affect children. ABCs comprise 1% of all primary bone tumors and occur most frequently during the first two decades of life. The diagnosis is made using a variety of imaging modalities and has the characteristic features of an expansile, radiolucent lesion that is often seen in the metaphyseal region of the bone and has fluid-fluid levels that are apparent on MRI. In the pediatric population, telangiectatic osteosarcoma and unicameral bone cyst (UBC) are the main differential diagnoses of an ABC. Giant cell tumors (GCTs) also include in differential diagnosis, which often manifest in patients older than 15 and do not penetrate the open physis although they develop after the physeal closure. Imaging alone cannot rule out telangiectatic osteosarcoma; therefore, a biopsy is recommended. A variety of treatment options have been described; traditionally, most patients are treated with curettage and bone grafting. Curettage alone, however, usually results in tumor recurrence following excision. A variety of adjuvants have been utilized with varying degrees of effectiveness to reduce the risk of local recurrence. When a cyst is in the pelvis, its location and size are such that surgery is a very risky option. Selective arterial embolization has significantly contributed to the development of effective treatments for these situations. Embolization or radiation, as well as denosumab therapy, are widely used as therapies for ABCs in anatomic locations where surgery would significantly increase morbidity.

As simple as it sounds? The treatment of simple bone cysts in the proximal femur in children and adolescents: Retrospective multicenter EPOS study of 74 patients.

Purpose: Simple bone cysts are among the most prevalent benign cystic tumor-like lesions in children. Proximal femoral simple bone cysts may require specific treatment because of increased fracture risk. With limited literature available on this specific localization, consensus regarding optimal treatment is lacking. We present a large international multicenter retrospective cohort study on proximal femoral simple bone cysts. Methods: All consecutive pediatric patients with proximal femoral simple bone cyst from 10 tertiary referral centers for musculoskeletal oncology were included (2000-2021). Demographics, primary treatment, complications, and re-operations were evaluated. Primary outcomes were time until full weight-bearing and failure-free survival. Results: Overall, 74 simple bone cyst patients were included (median age 9 years (range = 2-16), 56 (76%) male). Median follow-up was 2.9 years (range = 0.5-21). Index procedure was watchful waiting (n = 6), percutaneous procedure (n = 12), open procedure (n = 50), or osteosynthesis alone (n = 6). Median time until full weight-bearing was 8 weeks (95% confidence interval = 0.1-15.9) for watchful waiting, 9.5 (95% confidence interval = 3.7-15.3) for percutaneous procedure, 11 (95% confidence interval = -0.7 to 13.7) for open procedure, and 6.5 (95% confidence interval = 5.9-16.1) for osteosynthesis alone (p = 0.58). Failure rates were 33%, 58%, 29%, and 0%, respectively (p = 0.069). Overall failure-free survival at 1, 2, and 5 years was 77.8% (95% confidence interval = 68.2-87.4), 69.5% (95% confidence interval = 58.5-80.5), and 62.0% (95% confidence interval = 47.9-76.1), respectively. Conclusion: A preferred treatment for proximal femoral simple bone cysts remains unclear, with comparable failure rates and times until full weight-bearing. Watchful waiting may be successful in certain cases. If not feasible, osteosynthesis alone can be considered. Treatment goals should be cyst control, minimizing complications and swift return to normal activities. Therefore, an individualized balance should be made between undertreatment, with potentially higher complication risks versus overtreatment, resulting in possible larger interventions and accompanying complications. Level of evidence: Level IV, retrospective multicentre study.

Primary Aneurysmal Bone Cyst in the Iliac Bone: A Case Report.

Introduction: Aneurysmal bone cysts (ABCs) are non-neoplastic expansile, vascular, osteolytic benign tumors in the long bone, spine, and sternum. The location in the pelvis is sparse. Case Report: A 12-year-old female presented with pain in her left pelvis for 6 months. On radiological examination, we found an expansile balloting lytic lesion involving almost the whole ilium and sparing the hip joint. There were multiple fluid levels seen on magnetic resonance imaging. The initial biopsy suggested ABC. Curettage and bone grafting were done along with electrocauterization and chemical cauterization. At 1-year follow-up, she is doing well without any complaints. Conclusion: This case report demonstrates a rare ABC of the ilium that was managed with curettage and bone grafting.

Pathological fracture increases the risk of unsatisfactory functional results and avascular necrosis in children with proximal femur simple bone cysts.

INTRODUCTION: Proximal femur simple bone cysts (SBCs) are rare in children, but with a risk of pathological fractures and the associated poor outcomes. This study aimed to evaluate the functional and radiographic outcomes of children with proximal femur SBCs. PATIENTS AND METHODS: 38 children with proximal femur SBCs treated surgically at our department, West China hospital, were enrolled in the study. Patients were divided into two groups according to whether pathological fractures presented before treatment. The non-fracture group received treatment of open curettage, cavity electrocauterization, bone grafting, and fixation (proximal femoral plate, intramedullary nail or Kirschner wire). The pathological fracture group received the same procedures of curettage, electrocauterization, grafting, and fixation. Autogenous iliac bone grafting was done in all cases, and the artificial bone was used as a supplementary based on the size of the cavity. Postoperatively, all patients underwent hip spica or similar orthosis immobilization for six weeks and received the same rehabilitation program after the removal of hip spica. Patients were evaluated by two independent observers, including the functional results based on the Ratliff's criteria, avascular necrosis, healing rate based on the Neer scoring system, coxa vara, and premature physeal arrest. We described the good outcome in Ratliff's criteria as "Satisfactory results", and fair and poor outcomes as "Unsatisfactory results." Grade 1 and grade 2 Neer results were termed as failures in treatment, and grades 3 and 4 were considered successes and healing. RESULTS: 38 patients with 38 hips (18 on the left side and 20 on the right side) were evaluated, including 9 females and 29 males, with a mean age of 9.0±2.6 years old (range, 5 to 14 years). There was no significant difference between these two groups in the baseline data of gender, age, side, grafting, staging, and fixation methods. The rate of unsatisfactory functional results in the pathological fractures group was 56.3% (9/16), significantly higher than that in patients without fracture (22.7%, 5/22. p= 0.047). There was also a significant difference in avascular necrosis of the femoral head between the pathological fractures group (7/16) and the group without fracture (2/22, p=0.021). Thirty cases presented with healing, including 13 in the fractures group and 17 in the non-fracture group (p=1.000), and eight cases were graded as failures (2 cases of grade 1 and 6 cases of grade 2). There were also no significant differences between these two groups in premature physeal arrest (2 in fracture group and 1 in non-fracture group, P=0.562), and Coxa vara (3 in the fracture group and 0 in non-fracture group, P=0.066). CONCLUSIONS: Pathological fracture significantly increases the risk of unsatisfactory functional results and avascular necrosis of the femoral head in patients with femoral neck SBCs. Prophylactic treatment and fixation of SBCs in weight bearing proximal femur region is better to manage without complications than managing with pathological fractures.

Aneurysmal bone cyst of the wrist hamate: a case report and literature review / 中华骨科杂志

A rare instance of an aneurysmal bone cyst (ABC) in the wrist hamate of a 30-year-old male were reported in this case report. The patient exhibited a 1.5 cm mass on the dorsal ulnar side of the right wrist, which was non-tender, with normal overlying skin temperature and preserved wrist flexion. Radiographic evaluation revealed a deformed hamate with extensive cystic degeneration and minimal subchondral bone. Computed tomography (CT) scans highlighted clear osteolytic changes, including a visible bony crest. Magnetic resonance imaging (MRI) depicted mixed signal intensity on T1 and T2 weighted images. A biopsy indicated thinning and softening of the hamate's dorsal cortex, revealing eroded bone and dark red soft tissue. Histopathological analysis confirmed the diagnosis of an aneurysmal bone cyst. The patient underwent resection of the right wrist hamate, bone grafting from the iliac crest, and stabilization with Kirschner wire, resulting in fusion of the capitate-hamate and fourth and fifth carpometacarpal joints. The postoperative course involved immobilization with plaster for six weeks, and a 15-month follow-up indicated no recurrence. A review of the literature revealed that ABCs involving carpal bones are rare, predominantly occurring in individuals under 30 years of age. Clinical manifestations typically include wrist pain, occasional mild swelling, limited wrist mobility, and reduced hand strength. Radiological findings are characterized by osteolytic changes with MRI showing low T1WI and high T2WI signal intensity, and liquid levels on axial images. Treatment predominantly involves osteotomy or curettage with bone grafting. Diagnostic hallmarks include osteoclast-like multinucleated giant cells, ossified areas, and cystic cavities partitioned by fibrous septa. Our findings, consistent with the literature, suggest a favorable prognosis for carpal bone ABCs when treated appropriately.

Efficacy of Percutaneous Treatment of Primary Aneurysmal Bone Cysts (ABCs): A Systematic Review and Meta-Analysis.

BACKGROUND: Percutaneous treatment for primary aneurysmal bone cysts (ABCs) has been widely accepted. The study aimed to evaluate the efficacy of various sclerotherapy agents on patients with primary ABCs. METHODS: A meta-analysis of relevant studies. A systematic search was conducted on five databases, resulting in the inclusion of 25 studies with different percutaneous agents. RESULTS: A total of 729 patients with primary ABCs were included. Patients were administered with Ethibloc, doxycycline, embolization, alcohol, polidocanol, and calcitonin with methylprednisolone, respectively. Overall, 542 (74.3%) patients with ABCs had complete healing, 120 (16.4%) had partial healing, 44 (6%) had no-ossification or failure, and 26 (3.5%) had a recurrence. However, there was a total of 45 (6.1%) patients who had surgical curettage after sclerotherapy. Among the sclerotherapy agents, doxycycline showed highly effective results with minimal complications and recurrence, but it required multiple injections per patient. Ethibloc and embolization also proved to be highly effective with fewer injections required but had a higher rate of complications. Absolute alcohol, polidocanol, and calcitonin with methylprednisolone had similar efficacity and favorable success with fewer complications and fewer injections. CONCLUSION: Percutaneous treatment showed promising results in treating primary ABCs. However, more robust research is needed to establish the best approach for sclerotherapy in clinical practice and to address the limitations of the current literature.

Arthroscopic Treatment of a Subchondral Bone Cyst via Stem Cells Application: A Case Study in Equine Model and Outcomes.

Subchondral bone cysts in horses represent one of the main causes of lameness that can occur in different anatomical locations. The study describes the treatment in regenerative therapy of the intracystic implantation of adipose tissue mesenchymal stromal cells (AMSCs) included in platelet-rich plasma (PRP). The ability of AMSCs to differentiate in osteogenic cells was tested in vitro and in vivo. Given the aim to investigate the application of AMSCs in bone defects and orthopedic pathologies in horses, a four-year-old male thoroughbred racing horse that had never raced before was treated for lameness of the left hind leg caused by a cyst of the medial femoral condyle. The horse underwent a new surgery performed with an arthroscopic approach in which the cystic cavity was filled with AMSCs contained in the PRP. Radiographs were taken 3, 5, and 10 months after the surgery to assess the development of newly regenerated bone tissue in the gap left by the cyst. Twelve months after the operation and after six months of regular daily training, the horse did not show any symptoms of lameness and started a racing career. According to the study, the use of AMSCs and PRP suggests promising benefits for treating subchondral bone cysts.

Aneurysmal bone cyst arising from the surgically removed craniofacial fibrous dysplasia in the long-term follow-up: a case report.

Fibrous dysplasia (FD) is a rare skeletal disorder characterized by abnormal fibro-osseous connective tissue replacing normal bone. Despite its benign behavior, craniofacial FD can cause morphological disfigurement, headache, and even blindness as a result of the produced mass effect. Surgical resection is recommended when the patient shows apparent clinical symptoms or aggravating facial asymmetry. Postoperative complications have been reported, such as hematoma, surgical site infection, abscess formation, resorption of the bone graft used for reconstruction, and recurrence. An aneurysmal bone cyst (ABC) is a rare benign bony lesion that can occur secondary to preexisting bone tumor. Secondary ABCs in craniofacial FD are extremely rare in the literature, accounting for less than 30, all of which are either case reports or series. We report an extremely rare case of symptomatic secondary ABC arising from craniofacial FD that had been misdiagnosed with abscess formation or recurrence and was surgically removed. Notably, 17 years elapsed between the primary surgery and the complication of secondary ABC. The patient underwent total removal of secondary ABC. After surgery, symptoms were relieved, with no recurrence observed during a 6-month follow-up.

Treatment of Spinal Aneurysmal Bone Cyst with Percutaneous Injection of Hydroxyapatite Osteoconductive Cement.

PURPOSE: The aim of this study was to evaluate treatment efficacy of percutaneous injection of hydroxyapatite-osteoconductive-cement in patients with spinal aneurysmal bone cysts. MATERIALS AND METHODS: The study was designed as a retrospective observational clinical study. We included patients who were diagnosed with of spinal aneurysmal bone cyst, at our institution between 2013 and 2020, and treated with percutaneous injection of osteoconductive cement: "Cerament"® (BONESUPPORT AB, Lund, Sweden). Typical clinical and radiological features of the ABCs treatment and follow-up were investigated. RESULTS: Our study included nine patients, two children and seven adults. Three different types of approaches were applied: (single pedicle approach in 3 patients; double pedicle approach in 2 patients; while in the remaining cases, a multiple access approach was used. VAS score decreased from 8.5 ± 0.5 before treatment to 4.1 ± 0.9 at 6-months-follow up. All of the patients reacted well to treatment, with none neurological complications, complete loss of pain and achieved osteosclerosis as radiological marker of treatment success. CONCLUSION: Treatment of symptomatic spinal ABC's with hydroxyapatite cement is effective to achieve complete pain reduction and sclerosis.

A Bone Cyst in the Cervical Region of the Vertebral Column: A Report of a Rare Case.

Of all primary spine tumors, 15% are benign osteolytic lesions known as aneurysmal bone cysts (ABCs). Owing to the involvement of surrounding neurovascular structures and the potential for cervical spine instability, ABCs in the cervical spine represent a relatively uncommon clinical entity with surgical resection that is extremely challenging. This report details a case of an ABC in the cervical spine affecting a 10-year-old child who presented at the Medical Services Center at Imam Muhammad Ibn Saud Islamic University. The patient manifested with neck pain, a history of trauma, limitations in cervical motion, and neurological changes over the course of clinical follow-up. Diagnostic measures included radiography and computed tomography. The child underwent surgery to stabilize the cervical spine and to excise both the tumor and the affected vertebrae. Given the high recurrence rate of previously described lesions, various additional techniques have been utilized in conjunction with surgical resection, such as radiation and embolization. This paper further discusses the patient's progress, the chosen treatment, and the range of available options. More research is needed to develop evidence-based treatment plans for cervical spine ABCs in younger patients.

Aneurysmal bone cyst-like changes developed in melorheostosis with epiphyseal osteopoikilosis.

Aneurysmal bone cyst (ABC) is a rare and usually painful condition, representing about 1% of all bone tumors. A geographical lytic, expansile, and septated radiological pattern, with fluid-fluid levels on MRI, is classically displayed. ABC can be a primary bone lesion (70% of patients) or can arise in an underlying condition and is subsequently named "ABC-like changes" (30%). ABC-like changes are more frequently encountered in skeletal segments affected by chondroblastoma, fibrous dysplasia, giant cell tumor, osteoblastoma, non-ossifying fibroma, and osteosarcoma. In this article, we describe the first case of ABC-like changes developed in association with an ultra-rare sclerosing bone disease: melorheostosis. Melorheostosis is characterized by recognizable patterns on radiological studies with a pathological increased bone density and a cortical thickening within the periosteal or endosteal space, usually with a "dripping candle wax" appearance. More rarely, other different radiological patterns can be observed, such as "osteopatia striata-like," "osteoma-like," "myositis ossificans-like," and mixed patterns. Pain and limb hypotrophy are the most common clinical manifestations. We report the case of a Caucasian male with a clinic-radiological diagnosis of melorheostosis (with epiphyseal osteopoikilosis) since the age of twelve. At the age of nineteen, he suffered from increased pain in the proximal right thigh, and the radiological control revealed an expansive septated lesion at the right proximal femoral bone. The diagnosis of ABC-like changes developed in melorheostosis was obtained after CT-guided bone biopsy and confirmed by open-incisional biopsy.

[Bone tumors in children and adolescents]. / Knochentumoren des Kindes- und Jugendalters.

Osseous lesions are rare; however, their incidence is increased in childhood and adolescence. The spectrum of osseous processes in this age group is limited, with benign lesions being much more prevalent than malignant tumors. For the differential diagnosis, it is essential to have in-depth knowledge of the more frequent bone diseases in children and adolescents. The current review presents these diseases based on the morphologic approach of the WHO classification, including giant cell-rich and cystic lesions, chondrogenic and bone-forming lesions [7]. Small round cell sarcomas which are now summarized in a separate chapter of the WHO classification have been described previously [12, 20].

The Efficacy of Denosumab in Treating Spinal Aneurysmal Bone Cyst: A Case Report.

The optimal treatment for aneurysmal bone cysts (ABCs) of the spine remains controversial. No treatment guidelines exist for the use of denosumab in aneurysmal bone cysts. In this report, we describe the results from a representative case and compare our experience with those of previously published reports. A 38-year-old male was referred for pain in the lower back and left leg. Radiographs and a needle biopsy specimen revealed a lumbar aneurysmal bone cyst, which was treated with denosumab chemotherapy. The pain in the lower back and left leg gradually improved, and at 16 weeks, the symptoms had resolved. Once a satisfactory local effect was achieved, denosumab therapy was discontinued. However, the erosive lesion subsequently expanded. After re-initiation of treatment, there was no subsequent evidence of recurrence. Single-therapy denosumab is an option for aneurysmal bone cysts. However, recurrences have been documented after denosumab termination, and the timing for cessation of denosumab is controversial.

A remarkable and aggressive aneurysmal bone cyst ravaging the femoral shaft, advancing to lung metastases: An extremely rare case.

INTRODUCTION AND IMPORTANCE: Aneurysmal bone cysts (ABCs) are relatively uncommon tumor-like lesions that require careful management. Reporting such cases is crucial to highlight the importance of understanding the physiopathology and treatment options associated with ABCs. Literature-based writing emphasizes the significance of reporting cases like the one presented here. The aneurysmal bone cyst, classified as a Tumor Rich in Giant Cells according to the latest World Health Organization (WHO) classification of soft tissue and bone tumors, has posed several hypotheses and challenge. This aggressive form and rare localization of this lesion necessitates thorough discussions regarding its management. CASE PRESENTATION: We present a compelling case of a 37-year-old patient, without any specific pathological history, with a giant diaphyseal aneurysmal bone cyst located in the right femur. Remarkably, the lesion had been progressing for a decade, leading to extensive destruction of the entire femoral diaphysis despite undergoing previous surgical interventions. The patient's unique circumstances highlight the unpredictable behavior and destructive potential of aneurysmal bone cysts in rare anatomical locations. DISCUSSION AND CONCLUSION: This case underscores the need for a comprehensive understanding of aneurysmal bone cysts and their management. The utilization of denosumab, an inhibitor of the RANK/RANKL system, as a medical treatment in conjunction with surgery resulted in a favorable therapeutic response, including a reduction in tumor mass. The current WHO classification, recognizing ABCs as Tumors Rich in Giant Cells, consolidates previous hypotheses and enables the development of new therapeutic protocols. The integration of surgery and medical treatment holds promise for improving outcomes in patients with aneurysmal bone cysts. In conclusion, advancements in understanding the physiopathology and treatment options are crucial for developing effective therapeutic protocols to these aggressive forms of ABCs.