An aneurysmal bone cyst (ABC) is a benign bone neoplasm that typically occurs during the first and second decades of life. ABC usually presents as a rapidly growing intramedullary expansile mass with multiple blood-filled cysts in the metaphysis of the long tubular bones. Here, we report a case of a periosteal solid ABC that was initially diagnosed as a high-grade surface osteosarcoma. A 10-year-old male was referred to our hospital for swelling and tenderness of the left upper arm. Radiography revealed periosteal mass without fluid-fluid levels. On performing open biopsy, the tumor showed hypercellular proliferation of uniform spindle to epithelioid cells with brisk mitotic activity (up to 12/2 mm2) and lace-like osteoid formation, which was diagnosed as a high-grade surface osteosarcoma. After one course of chemotherapy using adriamycin and cisplatin, peripheral sclerosis was conspicuous, which led to pathological review and revision of diagnosis as \"possibly osteoblastoma.\" The patient was disease-free for 4 years after marginal resection and curettage. Retrospective nanopore DNA sequencing unexpectedly detected a PAFAH1B1::USP6 rearrangement. The fusion gene was further validated using reverse transcription-polymerase chain reaction and the diagnosis was revised to ABC. Chromothripsis involving chromosome 17 has also been identified. Methylation analysis classified the present tumor as an ABC or non-ossifying fibroma using t-distributed stochastic neighbor embedding and unsupervised hierarchical clustering. This case report highlights the utility of nanopore DNA sequencing for soft tissue and bone tumor diagnosis.

Background  A widely accepted set of imaging criteria or classification has not yet been adopted to evaluate response to treatment by percutaneous sclerotherapy for aneurysmal bone cyst (ABC). In this article, we described and illustrated the Royal Orthopaedic Hospital (ROH) scoring system which is a new, reproducible, and objective tool to evaluate the radiological response. We also reported our institutional experience in the efficacy of computed tomography (CT)-guided sclerotherapy for treating such lesions. Patients and Methods  A retrospective analysis was conducted for 19 patients who underwent CT-guided sclerotherapy with doxycycline and albumin to treat ABC. Follow-up magnetic resonance imaging, at a minimum of 12 months, was assessed according to the four ROH scoring system parameters: cystic component, fluid-fluid level, presence of consolidation, and cortical integrity. The cumulative score was used to grade response as either: excellent, good, equivocal, or poor. Results  Out of 19 patients with a mean age of 17.8 years, 11 cases occurred in the long bones, 5 cases in the pelvis, and 1 in each of the C3 vertebral body, scapula, and talus. The mean parameter of response score for cystic component was 2, fluid-fluid level was 1.3, consolidation was 2, and cortical integrity was 2.1. Four cases showed excellent response, 12 cases showed good response, 2 cases showed equivocal response, and 1 case showed poor response. Interrater reliability was excellent (κ = 0.9). Conclusion  The ROH scoring system provides the radiologist and surgeon with an objective method to score imaging parameters of response independently and achieve a grade based on the cumulative score.

UNASSIGNED: Aneurysmal bone cysts (ABCs) are aggressive and benign tumors that primarily affect children and adolescents. The standard course of treatment for ABCs involves surgical excision or curettage with a bone transplant or cement to repair the deficiency. Denosumab, a monoclonal antibody that inhibits receptor activator of nuclear kappa B ligand, is used to treat osteoporosis, skeletal metastasis, and giant cell tumors of the bones.
UNASSIGNED: This case study details the therapeutic treatment of a female patient, age 22, who had a recurring aggressive ABC of the distal tibia. The patient was initially treated using curettage and lesion filling. However, recurrence of the osteolysis was observed 9 months later that led to subsequent interventions involving absolute alcohol sclerotherapy in multiple sessions. However, these interventions failed to achieve ossification. Following unsuccessful surgical and sclerotherapy treatments, the patient was administered denosumab, which led to a positive response. Regular radiographic and clinical follow-up demonstrated significant improvements in ossification and pain reduction. During the course of the 12-month treatment, the frequency of visits was gradually reduced. Further, follow-up and monitoring revealed the effectiveness of the local control and long-term treatment.
UNASSIGNED: This case report highlights the ability of denosumab to manage recurrent aggressive ABCs after surgical or sclerotherapy failure.

Aneurysmal bone cyst is a rare osteolytic lesion of uncertain etiology, commonly observed in the lower limbs, with only 1-2% of reports in gnathic bones. We present the case of a 27-year-old male patient referred to the oral and maxillofacial surgery and traumatology service due to complaints of paresthesia in the mental region and increased mandibular volume. Physical examination revealed midline shift and hard consistency. Imaging examinations demonstrated a radiolucent/hypodense lesion with disruption of the mandibular cortices. The histopathological examination of incisional biopsy material led to the diagnosis of a central giant cell lesion. The patient underwent surgical resection, and the histopathological analysis of the specimen revealed a predominantly solid lesion, characterized by blood-filled spaces of varying size, not covered by epithelium or endothelium, with the presence of spindle cells, multinucleated giant cells, and basophilic osteoid material, concluding the diagnosis of mixed-type aneurysmal bone cyst. Despite being uncommon, aneurysmal bone cysts should be considered in the differential diagnosis of volumetric increase in the gnathic bones of young patients.

Aneurysmal bone cysts (ABCs) are rare benign bone lesions with a predilection for the metaphysis of long bones. They are often cystic, expansive, and osteolytic and may result in bony deformity. In general, there remains debate about optimal treatment for ABCs; however, the mainstay typically consists of a combination of curettage, bone grafting, and considering the need for internal fixation and osteotomies. The goals of treatment include preserving bony anatomy while eliminating the lesion. There is sparse literature regarding the treatment of osteoarthritis adjacent to benign bony tumors. If total hip arthroplasty is chosen as a treatment option, diligent preoperative planning is required, and the surgeon must assess the patient\'s bone stock, account for bony deformity, and utilize specific implants and techniques based on the patient\'s characteristics. We present a case of an adult patient with proximal femur ABC and symptomatic adjacent hip osteoarthritis who underwent treatment with total hip arthroplasty.

Tumors that develop on the chest wall are usually rare. This case report highlights a rare occurrence of a giant cell tumor originating from the anterior arch of the fourth rib. The patient, a 21-year-old male, presented with a bulging mass that had been gradually increasing in size over an eight-month period, reaching dimensions of 12 x 8 cm. Despite the noticeable swelling, the patient reported no associated pain or discomfort and denied any history of weight loss or trauma. The absence of chest pain or cardiovascular symptoms distinguished this case from other chest wall pathologies. This report underscores the importance of considering rare entities such as giant cell tumors in the differential diagnosis of chest wall masses, especially in cases where clinical presentation and patient history do not align with more common conditions.

Background: Aneurysmal bone cysts (ABCs) are osteolytic, non-malignant, vascular lesions of the bone. Pathological fractures can be a manifestation of the ABCs, which occur in about 8% of ABCs. Different treatments have been described in the literature, but, nowadays, an optimal management of the pathological fractures in patients with ABCs is still a matter of debate and there are no standard guidelines for treatment nor any shared indication about the best surgical intervention. The aim of our study is to review the current literature available on this matter exploring and confronting different surgical treatments for pathological fractures in ABC in order to clarify the surgical approach to these patients. Methods: A systematic review of the literature indexed in PubMed, MEDLINE, and Cochrane Library databases was carried out. The Preferred Reporting Items for Systematically Reviews and Meta-Analyses (PRISMA) were followed. Results: A total of 37 articles were relevant and were finally included in the study. In total, we reached a population of 140 patients. Of the 140 patients included in the review, 124 patients (88.6%) underwent curettage surgery, 15 patients (10.7%) underwent en bloc resection surgery. A total of 47% of patients (70) underwent synthesis surgery with a plate, screw, nail, or external fixator. Adjuvant treatments were used in 8.6% of patients (12). Complications involved 20.7% of the patients (29). Conclusions: In conclusion, the treatment of pathological fractures in aneurysmal bone cysts requires careful patient assessment, considering factors such as age, the presence of open growth plates, the location of the lesion, and the surgeon\'s expertise.

Reconstruction options for giant cell tumors (GCTs) of bone are limited and challenging due to the amount of structural compromise and the high recurrence rates. This is especially true for GCTs of the foot and ankle, as the area is vital for weight bearing and function. The typical treatment for GCTs is currently excision, curettage, and cementation, although that is not always effective. A 36-year-old otherwise healthy female presented with an original diagnosis of a large aneurysmal bone cyst (ABC) of the distal tibia that had recurred despite two previous attempts at treatment with resection and cementation. She was treated with surgical resection of the lesion, reconstruction, and ankle and subtalar joint arthrodesis with a tibiotalocalcaneal intramedullary nail in combination with a trabecular metal cone. The final pathology of the intraoperative samples was consistent with GCT. Postoperatively, she recovered well, and her imaging was consistent with a successful fusion. This case report provides evidence that tibiotalocalcaneal fusion with a unique combination of hindfoot nail and trabecular metal cone construct in a single procedure is a successful option for the treatment of large, recurrent GCT lesions in the distal tibia.

UNASSIGNED: Aneurysmal bone cysts (ABCs) are aggressive, expansile, and locally destructive vascular lesions. The exact etiology of ABCs is currently unknown and hypothesized to be related to vascular malformations or disruption of osseous vascularity. To date, there have been no reports describing the development of pubic ABCs following penile inversion vaginoplasty (PIV).
UNASSIGNED: This report describes the development of a pubic ABC in a transgender patient who had previously undergone PIV, possibly indicating a very rare complication of this gender-affirming operation.
UNASSIGNED: A 37-year-old transgender female was initially referred to the orthopedic oncology clinic for evaluation of a 12-month history of left hip and groin pain. She had undergone gender-affirming PIV about 19 months prior to presentation. Magnetic resonance imaging (MRI) with contrast revealed a low T1 signal intensity and heterogenous T2 hyperintensity 7.5 × 4.9 × 4.3-cm destructive mass in the left superior pubic ramus extending across the pubic symphysis into the right superior pubic ramus. A needle core bone biopsy demonstrated a variably cellular spindle and round lesion with islands of osteoid formation and focal necrosis. The cells were negative for CD34, S100, and desmin. There was no evidence suggesting osteosarcoma, and final review favored the diagnosis of an ABC. Given the highly destructive nature of the mass, it was resected, and the resulting wound was reconstructed with a biologic dermal mesh.
UNASSIGNED: Although it is impossible to distinguish coincidence from causation in this case, the patient\'s recency of PIV and development of a rare ABC in a nearby bone warrants the speculation and discussion provided in this report.

BACKGROUND: Aneurysmal bone cysts (ABCs) are benign, osteolytic lesions that can occur in long bones, vertebrae, or rarely, the skull. Here the authors present the case of a 15-year-old male with a primary ABC of the left frontoparietal skull along with a review of the literature to provide insight into the nature of this rare disease.
METHODS: An otherwise healthy 15-year-old male presented with a tense, painful lesion of the left frontoparietal scalp. He could not identify any inciting trauma, but first noted the lesion less than 2 weeks prior to presentation with progressive enlargement. Cranial imaging revealed a lytic skull lesion with fluid-fluid levels suggestive of ABC. Curative therapy was provided via wide excision of the lesion and calvarial reconstruction of the resultant skull defect. This was performed without complication, and histopathological evaluation confirmed the diagnosis of primary ABC.
CONCLUSIONS: ABCs of the skull are rare entities and most often arise in the skull base versus the calvaria. Typically, these lesions are associated with an underlying bone pathology (secondary ABCs) but can be rarely seen as isolated lesions (primary ABCs). Clinical management consists of excision and adjuvant therapy for underlying pathology where appropriate.