METHODS: We describe 2 case studies, involving a 10-year-old girl with an aneurysmal bone cyst and a 12-year-old adolescent boy with Ewing sarcoma. The patient with Ewing sarcoma was previously managed with wide surgical excision and fibular graft reconstruction and subsequently experienced significant graft resorption, hardware failure, and fracture 24 months after operation. A revision limb salvage attempt was undertaken. In both cases, fibular strut grafts were harvested and fixed with intramedullary k-wires to recreate the medial and lateral columns of the distal humeral triangle.
CONCLUSIONS: The technique achieved complete osseous integration, structural support, and functional restoration of the elbow in both cases, with good functional outcomes.

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 primary bone tumours that rarely occur in the spine and generally affect one vertebral level in adolescents. Here, we present an unusual case of a multilevel thoracolumbar ABC, which presented a unique surgical challenge due to its infiltrative and destructive nature. A teenage male presented with back pain, paresthesias and a mildly spastic gait. MRI of the thoracolumbar spine revealed an expansive, multicystic mass extending from the left T12-L1 vertebral bodies into adjacent musculature. The patient underwent a two-stage surgical approach with decompression of the spinal cord and instrumentation to stabilise the vertebral column. The first stage involved posterior decompression, laminectomy and facetectomies, followed by pedicle-based instrumentation from T10 to L3. This was followed by a vertebrectomy and anterior stabilisation with an expansile cage from T11 to L2. A gross total resection was achieved with the patient maintaining full neurological function.

Aneurysmal bone cyst (ABC) is a non-malignant, locally destructive, blood-filled lesion in the bone that tends to grow aggressively. A young girl presented with a rapid recurrence after aggressive surgery of a large symptomatic sacral-spinal ABC. After a multidisciplinary tumour board, she was successfully treated with sclerotherapy and monthly intravenous denosumab. The patient has maintained asymptomatic for over 36 months now and has returned to full activity and strength. She never required surgery and has had radiologic resolution of the lesions. Treatment of recurrent ABC requires a multidisciplinary team approach. We believe this to be the first report to use this combined therapy to provide an alternative to morbid surgery for children with ABCs.

We report a case of an aneurysmal bone cyst (ABC) originating in a rib. A 34-year-old woman was admitted to our medical department for evaluation of left rib pain and an abnormal shadow in the left 7th rib observed on chest radiography. Computed tomography (CT) revealed an osteolytic lesion involving the left 7th rib. Positron emission tomography/CT showed slight fluorodeoxyglucose uptake in the lesion. We performed 7th rib resection with a 4 cm margin from the tumor, including the intercostal muscles in the 6th and 7th interspaces. Histopathological examination of the resected specimen showed multiple blood-filled spaces and fibrous trabeculae, which confirmed the diagnosis of an ABC. The patient\'s postoperative course was uneventful. Although rare, clinicians should consider ABCs in the differential diagnosis of rib tumors.

METHODS: A 16-year-old boy presented with a recurrent distal femur aneurysmal bone cyst accompanied by a combined sagittal knee deformity (20° of femoral antecurvatum and 26.8° of tibial recurvatum) and limb shortening. After preoperative planning, the treatment involved new intralesional curettage, phenolization, and bone allograft filling. Additional procedures included distal extension femoral osteotomy with plate fixation, and proximal tibial osteotomy with, gradually corrected through a hexapod frame. At 2-year follow-up, lower limbs exhibited normoalignment and equal length.
CONCLUSIONS: Complex knee deformities may occur with tumoral lesions around the knee but can be effectively addressed through double osteotomy and application of a hexapod frame.

Objective: To investigate the radiologic, pathologic, and molecular features of simple bone cysts (SBC), and their differential diagnoses. Methods: Fourteen cases of SBC were collected at the Department of Pathology, the First Affiliated Hospital of Nanjing Medical University from 2017 to 2022, and fluorescence in situ hybridization (FISH) was performed for retrospective analysis. Results: There were 14 patients, including 7 females and 7 males, with age range of 7 to 45 (median 29) years. The most common complaint was pain, including 4 cases with pathological fracture and 5 with history of previous trauma. The tumor size ranged from 3.4 to 13.5 (median 5.6) cm. The lesion involved the femur (n=4), humerus (n=5) and iliac bone (n=5). Radiologic diagnoses included SBC, aneurysmal bone cyst, and giant cell tumor of the bone or its combination with aneurysmal bone cyst-like region and fibrous dysplasia. Histologically, the cyst walls of the lesions were composed of fibrous tissue, fibrin-like collagen deposits, bone-like matrix and occasional woven bone. The lesional cells were spindled to ovoid, with scattered osteoclast-like giant cells, foamy histiocytes, hemosiderin deposits and cholesterol clefts. In 6 cases there were nodular fasciitis-like areas. Immunohistochemically, the spindled to ovoid cells were positive for SMA, EMA and SATB2 in varying degrees. FISH detection was performed in all 14 cases and EWSR1/FUS rearrangement were found in 9 cases. One case of FUS::NFATC2 fusion was detected by next-generation sequencing. Nine cases of SBC with the rearrangement were more cellular, and there were more mitotic figures in the recurrent FUS::NFATC2 fusion tumor. Clinical follow-up was obtained in all 14 cases with the time ranging from 5 to 105 (mean 46) months. Amongst them, the tumor with FUS::NFATC2 rearrangement had local recurrence twice after the first local excision, but had no more recurrence or metastasis 34 months after the subsequent segmental resection. The other 13 cases had no recurrence. Conclusions: EWSR1 or FUS rearrangement is most commonly identified in SBC, suggesting that SBC might be a neoplastic disease. In cases where the radiologic appearance and histomorphology are difficult to differentiate from aneurysmal bone cyst, FISH detection can aid in the definitive diagnosis.
目的： 探讨单纯性骨囊肿（simple bone cyst，SBC）的临床影像学、病理形态学、分子遗传学特点、诊断及鉴别诊断。 方法： 收集南京医科大学第一附属医院病理学部2017—2022年诊断为SBC的病例14例，行荧光原位杂交（FISH），回顾性分析影像学、病理学及分子遗传学特征。 结果： 14例SBC中，男性7例，女性7例，年龄7~45岁（中位年龄29岁）。临床表现以局限性疼痛最为常见，其中4例伴有病理性骨折，5例伴有既往创伤史。最大径3.4~13.5 cm（中位5.6 cm），累及肱骨（5例）、髂骨（5例）、股骨（4例）。影像学诊断有SBC、动脉瘤性骨囊肿、骨巨细胞瘤、骨巨细胞瘤合并动脉瘤性骨囊肿样区域，以及纤维结构不良。形态学上，低倍镜下囊壁由纤维结缔组织构成，可以见到纤维蛋白样沉积物，部分有骨样基质及编织骨的形成。高倍镜下，囊壁可见呈胖梭形、卵圆形病变细胞，散在的破骨样巨细胞，堆积的泡沫样组织细胞，含铁血黄素的沉积以及胆固醇裂隙，6例可见类似结节性筋膜炎样的形态。免疫表型上，囊壁内衬细胞可见平滑肌肌动蛋白、上皮细胞膜抗原、SATB2不同程度的表达。14例均行FISH检测，发现9例涉及FUS或ESRW1基因的重排，其中1例行二代测序发现FUS：：NFATC2融合。9例发生重排的SBC细胞密度略高，其中FUS：：NFATC2融合患者复发标本可见核分裂象。14例随访5~105个月（平均46个月），其中FUS：：NFATC2重排患者术后2次局部复发，第2次复发后行瘤段切除术34个月未复发，其余13例均无复发。 结论： SBC中有很大一部分存在EWSR1或FUS的重排，提示SBC可能是一个肿瘤性疾病。当影像学和形态学特征对于鉴别诊断SBC和动脉瘤性骨囊肿困难时，可结合FISH检测辅助鉴别。.

BACKGROUND: Juvenile Psammomatoid Ossifying Fibroma (JPOF) is a type of noncancerous bone tumor that usually affects adolescents in the craniomaxillofacial area. Clinical manifestations are usually symptoms caused by the tumor\'s invasive compression of surrounding tissues. Aneurysmal Bone Cyst (ABC) is also a benign bone tumor, and it typically occurs in long bones and the spine. Only 2% to 3% of cases occur in the head and neck. Due to the rarity of this combination of clinical cases, clinicians face difficulties in comprehensively understanding this complex lesion. Therefore, a comprehensive review of the clinical manifestations and characteristic imaging findings is necessary for surgeons.
METHODS: On April 6, 2019, a 13-year-old boy presented with left maxillofacial bulge and pain for 1 month. Magnetic resonance imaging of the paranasal sinuses showed an irregular hive-like mass signal in the left maxillary sinus, and cystic changes with fluid levels were seen in the lesion. After the initial diagnosis of JPOF with primary ABC, we decided to perform a facial mid-facial resection of maxillary sinus tumor to remove the tumor tissue. Finally, after 3 recurrences and 4 operations, there was no tumor recurrence for 20 months after the last operation, and the patient was still under continuous follow-up.
CONCLUSIONS: This case provided a reference for the diagnosis and treatment of JPOF combined with ABC. In particular, a new understanding of the association between the two diseases and the management of recurrence were proposed, which had the potential to improve clinical understanding of this complicated condition.

BACKGROUND: Aneurysmal bone cyst (ABC) is an uncommon, benign, vascular multicystic bony lesion that most frequently develops in the first two decades of life. The metaphysis of long bones, pelvic, and vertebral column are the most common locations. The precise underlying pathophysiology of ABCs formation remains unclear; however, it is believed that reactive processes subsequent to trauma or vascular disturbance may play an important role. Involvement of the skull base rarely occurs with a prevalence of up to 5% of intracranial ABCs.
METHODS: An 18-year-old adolescent female with a history of progressive blurred vision since three months ago presented to our office. The brain and orbital MRI demonstrated no abnormal findings. After three months of glucocorticoid treatment with the diagnosis of multiple sclerosis, the visual impairment of the left eye deteriorated abruptly. The patient underwent an MRI and the imaging study demonstrated a well-defined 30 × 22 × 20-mm lesion at the anterior clinoid process with an extension to the optic canal and ethmoid sinus. The patient underwent pterional craniotomy, and the tumor was resected. The histopathological examination was suggestive of ABC.
CONCLUSIONS: ABC and other conditions should be considered in young-age people with an early unilateral decline in vision and imaging studies should be obtained in early stages and during follow-ups.

OBJECTIVE: We report a case of fibrous dysplasia (FD) with aneurysmal bone cyst (ABC)-like change in a child with orbital involvement, review the related cases, and discuss clinical features, therapy, and prognosis of this disease.
METHODS: A 10-year-old girl had right proptosis (degree of exophthalmos: OD 16 mm, OS 13 mm) and limited vision (visual acuity: OD 1.0, OS 0.8) without trauma. Preoperative CT showed a 5.0*4.3 cm right-sided crania-orbital communicating tumor. MRI indicated a well-defined multicystic mass with scattered fluid levels and soap bubble-like alterations. The child underwent total tumor resection and orbital parietal titanium mesh reconstruction. At 20 months of follow-up, the child has recovered from ocular problems, and the tumor has not recurred.
CONCLUSIONS: FD combined with ABC rarely occurs in orbit and generally begins with ocular symptoms. The etiology is uncertain. Early diagnosis and surgery are essential. Complete resection is suggested whenever possible because residual lesions may recur.