Outcomes and complications of surgical treatment modalities for simple bone cysts of the humerus in children and adolescents.

PURPOSE: The aim of this study was to evaluate and compare different surgical treatment modalities for simple bone cysts (SBC) of the humerus regarding their effectiveness and recurrence rate. METHODS: In this retrospective study, patients who received surgical treatment for previously untreated primary SBCs of the humerus were analyzed. Demographic data, cyst-specific as well as treatment-specific parameters, complications, treatment failures, and recurrence rates were collected and correlated with different treatment modalities. Observed procedures were categorized as open procedure (n=20) or osteosynthesis alone (n=3). For the open procedure group, four subgroups could be defined. RESULTS: Twenty-three patients were included. The mean age at diagnosis was 11.6 ± 2.5 years, and the mean postoperative follow-up was 3.9 ± 2.6 years (range 1.0-10.3). After surgical intervention, a total of five (21.7%) patients showed at least one recurrence. Fracture occurred in three (13.0%) cases. The incidence of treatment failure was significantly higher in the curettage, allograft, adjuvants group, with five (83.3%) of six cases showing recurrence, than in the other subgroups (≤ 25.0%) including the osteosynthesis alone group (p=.024). For the open procedure group, the failure-free survival rates were 80.0% after two years and 50.4% after five years. For the three cases treated by osteosynthesis alone, no failures were observed. CONCLUSION: Open procedures showed similar failure rates except for the subgroup using curettage, allograft, and adjuvants which showed significantly higher treatment failure. Promising results were observed in the group which received solely osteosynthesis without cyst excision or filling, as no treatment failure was observed here.

No NFATC2 fusion in simple bone cyst of the jaw.

AIMS: Simple Bone Cysts (SBCs) predominantly occur in long bones and 59% harbour NFATC2 rearrangements. Jaw SBC is rare and was previously referred to as traumatic bone cyst. It can rarely occur in association with cemento-osseous dysplasia (COD). To determine whether jaw SBCs represent the same entity as SBC of the long bones, or if they have a different molecular signature, we collected 48 jaw SBC cases of 47 patients to assess NFATC2 rearrangement. METHODS AND RESULTS: Out of the 48 cases, 36 could be used for fluorescence in-situ hybridization (FISH), of which nine (two of which associated with COD) were successful using an NFATC2 split probe. The remaining cases failed to show adequate FISH signals. All nine cases lacked NFATC2 rearrangement and five of these showed no detectable gene fusions using Archer FusionPlex. CONCLUSION: In our study, NFATC2 rearrangement is absent in solitary jaw SBC (n = 7) and COD-associated SBC (n = 2). Our findings suggest that SBC presenting in the jaw is molecularly different from SBC in long bones. Future molecular studies may confirm the absence of clonal molecular aberrations in SBC of the jaw which would support a non-neoplastic, reactive origin.

Implementation of Copy Number Variations-Based Diagnostics in Morphologically Challenging EWSR1/FUS::NFATC2 Neoplasms of the Bone and Soft Tissue.

In the last decade, new tumor entities have been described, including EWSR1/FUS::NFATC2-rearranged neoplasms of different biologic behavior. To gain further insights into the behavior of these tumors, we analyzed a spectrum of EWSR1/FUS::NFATC2-rearranged neoplasms and discuss their key diagnostic and molecular features in relation to their prognosis. We report five patients with EWSR1/FUS::NFATC2-rearranged neoplasms, including one simple bone cyst (SBC), two complex cystic bone lesions lacking morphological characteristics of SBC, and two sarcomas. In three cases, fluorescence in situ hybridization (FISH) and in all cases copy number variation (CNV) profiling and fusion analyses were performed. All patients were male, three cystic lesions occurred in children (aged 10, 14, and 17 years), and two sarcomas in adults (69 and 39 years). Fusion analysis revealed two FUS::NFATC2 rearrangements in two cystic lesions and three EWSR1::NFATC2 rearrangements in one complex cystic lesion and two sarcomas. EWSR1 FISH revealed tumor cells with break-apart signal without amplification in one complex cystic lesion and EWSR1 amplification in both sarcomas was documented. CNV analysis showed simple karyotypes in all cystic lesions, while more complex karyotypes were found in NFATC2-rearranged sarcomas. Our study supports and expands previously reported molecular findings of EWSR1/FUS::NFATC2-rearranged neoplasms. The study highlights the importance of combining radiology and morphologic features with molecular aberrations. The use of additional molecular methods, such as CNV and FISH in the routine diagnostic workup, can be crucial in providing a correct diagnosis and avoiding overtreatment.

Surgical treatment of benign lesions and pathologic fractures of the proximal femur in children.

PURPOSE: Benign lesions of the proximal femur region, such as simple bone cysts, aneurysmal bone cysts, and fibrous dysplasia, are common in children. Benign lesions may cause pathologic fractures, limb length inequities, and growth disturbances. Differential diagnoses, e.g., malignant bone tumors and osteomyelitis, are sometimes difficult to rule out. OBJECTIVE: We aimed to evaluate outcomes in children with benign lesions of the proximal femur treated with curettage, bone grafting, and plate fixation. METHODS: In this retrospective study, we included 30 children (median age 10.5 years; range 1.1-17.8 years) suffering from bone cysts and tumor-like lesions of the proximal femur region treated between 2002 and 2018. We analyzed plain X-ray images and CT scans in all children and obtained MRI scans in a selected group of children (63.3%). We examined histopathologic biopsy results for all bone lesions before initiating treatment. Surgical management comprised tumor curettage with adjuvant high-speed drilling and allogenic bone grafting supplemented by bone graft substitutes before plate fixation. Median follow-up interval was 87 months (range 24-156 months). We evaluated the healing of lesions according to Capanna's classification and rated functional outcomes according to Merle d'Aubigné and Postel score. RESULTS: Overall, 25 of 30 (83.3%) patients were admitted to hospital because of a pathologic fracture. We diagnosed simple bone cysts in 15 (50.0%) patients, aneurysmal bone cysts in 7 (23.5%) patients, and fibrous dysplasia in 8 (26.5%) patients. Bone consolidation was achieved in 22 of 30 (73.3%) patients after a mean of 5 months (range 3-7 months). The main complication was recurrence of the lesion in 4 of 30 (13.3%) patients. With respect to the Merle d'Aubigné and Postel scores, 17 of 30 (56.7%) patients obtained an excellent result (18 points), while 12 (40.0%) patients had a good result (15-17 points) and only 1 (3.3%) patient had a fair result (14 points). CONCLUSION: Surgical treatment of bone cysts and tumor-like lesions of the proximal femur by local resection or destruction of the lesion, followed by filling the defect with bone graft material and internal stabilization represents a safe and effective treatment option in children. LEVEL OF EVIDENCE: Therapeutic, retrospective comparative study-Level III.

Identification of EWSR1-NFATC2 fusion in simple bone cysts.

AIMS: Simple bone cysts are benign intramedullary tumours primarily involving the long bones in skeletally immature individuals. Several mechanisms have been proposed for their pathogenesis. Although the diagnosis is typically straightforward, the interpretation can be problematic, because of superimposed fracture causing them to resemble aneurysmal bone cysts and other tumours. EWSR1-NFATC2 or FUS-NFATC2 fusions, which are characteristic of a subset of aggressive round cell sarcomas, have been recently detected in simple bone cysts. The aim of this study was to examine the clinicopathological and molecular features in a series of simple bone cysts. METHODS AND RESULTS: Using RNA-based next-generation sequencing and/or fluorescence in-situ hybridisation, we investigated the presence of EWSR1 or FUS rearrangements in nine simple bone cysts. The patients were five females and four males, aged 3-23 years (median, 14 years); the tumours ranged from 19 mm to 160 mm (median, 46 mm) in size, and involved the femur (n = 3), humerus (n = 2), fibula (n = 2), tibia (n = 1), and iliac wing (n =1). We identified three cases with EWSR1-NFATC2 fusion (showing identical breakpoints to those in EWSR1-NFATC2 sarcomas) and one additional case with FUS rearrangement. Unlike in EWSR1-NFATC2 sarcomas, immunohistochemical expression of NKX3.1 and NKX2.2 was absent in two simple bone cysts tested. CONCLUSIONS: More than 40% of simple bone cysts harbour genetic alterations confirming that they are neoplastic, investigation of EWSR1 and/or FUS rearrangement may help to distinguish simple bone cysts from mimics, and NFATC2 rearrangement is not pathognomonic of malignancy.

Intraosseous lipomas originating from simple bone cysts.

PURPOSE: Fatty or part-fatty intraosseous lesions are occasionally encountered while imaging the skeletal system. A number of case reports have proposed involution of calcaneal bone cysts to intraosseous lipomas, but this has never been proven. This paper sets out to prove that simple bone cysts (SBCs) can involute to fatty lesions indistinguishable from intraosseous lipomas. MATERIALS AND METHODS: The pathology and PACS databases at 2 specialist orthopedic hospitals were retrospectively interrogated for all cases of intraosseous lipomas or SBCs with cross-sectional imaging follow-up for SBCs and precursor or follow-up imaging for intraosseous lipomas, in the time period from August 2007 to December 2016. For intraosseous lipoma cases, these were only included if change in imaging appearances was observed. RESULTS: There was no case of change in the appearance in intraosseous lipomas. Six cases of SBC with cross-sectional imaging follow-up were identified in one participating hospital and none in the other. The 6 cases were comprised of 4 male and 2 female patients. Two were located in the proximal humerus, one in the proximal tibia, and 3 in the os calcis. All cases demonstrated filling in of the cystic lesion with fat from the periphery, in 2 cases complete filling in, and in 4 cases partial fatty conversion. CONCLUSION: SBCs can heal with fatty conversion of the cystic cavity, with partly cystic remnants. It is proposed that at least part of the so-called intraosseous lipomas are healed simple bone cysts.

Treatment of simple bone cysts of the humerus by intramedullary nailing and steroid injection.

BACKGROUND: Simple bone cysts (SBCs) are common benign lytic bone lesions in children. This study focused on exploring a clinical treatment method, minimally invasive intramedullary decompression and drainage with elastic stable intramedullary nailing (ESIN) combined with intralesional injections of steroids, and evaluated its effectiveness, complications and morbidity through functional and radiographic outcomes. METHODS: The postoperative recovery of 18 children who suffered from SBCs of humerus was evaluated (mean follow-up, 40 months) from January 2009 to December 2016. These patients (11 males, 7 females; 8 in the left, 10 in the right; mean age, 10.9 years old) were treated with minimally invasive intramedullary decompression and drainage with ESIN combined with intralesional injections of steroids. The diagnosis was based on not only pre-operative typical medical images (X-rays/CT/MRI) but also surgical findings and pathological diagnosis. Radiological and functional outcomes were evaluated according to Capanna and Musculoskeletal Tumor Society (MSTS) score. The interclass differences were analyzed by t-test. RESULTS: According to Capanna and MSTS criteria, after treatment, 14 patients made full recoveries which was presented by all the cysts filled with bone tissue, and 4 patients made partially recoveries, which were presented by cystic spaces partially filled with low density bone. All the cysts responded to treatment method, and there was no cyst recurrence. All except 2 patients had good functional results. One of the two patients had irritation of the end of the nail and one patient had a valgus deformity. CONCLUSIONS: Treatment for SBCs of humerus by minimally invasive intramedullary decompression and drainage with ESIN combined with intralesional injections of steroids is safe, effective and convenient. The clinical effect is satisfactory and worth popularizing.

Cranial vault unicameral bone cyst.

Introduction: Unicameral bone cysts (UBC), also known as simple bone cysts, are common benign bone lesions filled with fluid, primarily occurring in children and adolescents. Although they can develop in any bone, UBCs usually affect the long bones.Materials & Methods: A 53 year old male patient was found incidentally to have a calvarian lesion in the parietal region overlying the superior sagittal sinus (SSS) (Figure 1). The differential diagnosis included a large arachnoid granulation, haemangioma of bone, a giant cell tumour or tuberculous infection. The patient was planned for elective surgery to remove the lesion and establish the diagnosis. Surgery was uneventful.Conclusion: To the best of our knowledge we describe the first case of UBC affecting the cranial vault. The patient underwent surgery.

Right iliac bone pathological fracture mimicking acute appendicitis.

Simple bone cyst (SBC) also known as unicameral bone cyst is a benign, radiolucent bone lesion that is seen commonly in childhood. These lesions are usually found incidentally although pain and swelling can be seen. The most common complication is a pathological fracture, and this is often the cause of presentation. Here, we present a 22-year-old male with right lower quadrant pain due to SBC related pathological fracture of right iliac bone which is mimicking acute appendicitis.

[Bone cysts-differential diagnosis and therapeutic approach]. / Knochenzysten ­ Differenzialdiagnose und therapeutisches Vorgehen.

The differential diagnosis of cystic lesions of the skeleton is multifarious. Besides patient age, the localization and radiologic morphology provide important information for a closer differentiation. Juvenile and aneurysmal bone cysts represent two frequent entities in growing patients. The fluid content of the cysts helps in distinguishing between juvenile and aneurysmal bone cysts. Whereas juvenile bone cysts contain clear fluid, the content of aneurysmal bone cysts consists of blood combined with solid tissue. With respect to progression, aneurysmal bone cysts show a higher activity than solitary bone cysts. The treatment of juvenile bone cysts usually consists of curettage including filling with bone replacement material. For aneurysmal bone cysts the additional use of adjuvants is recommended. Bone cement is preferably used for filling. It shows favorable properties for prophylaxis of recurrence and facilitates the recognition of relapses. Both juvenile and aneurysmal bone cysts often show recurrences.

An unusual case of proximal humeral simple bone cyst in an adult from secondary cystic change.

BACKGROUND: Simple bone cysts (SBC) have been documented to occur in adults with closed physeal plates, most commonly affecting the calcaneus in this patient subset. Although most authors theorize an association to trauma, etiology of simple bone cysts remains an enigma up to now. CASE PRESENTATION: A 26-year-old kickboxing coach sought consult for a painful right shoulder which on radiographs and magnetic resonance (MR) imaging showed a proximal humeral lesion with signs of ossification. The patient was lost to follow-up but again sought consult after 3 years for the recurring complaint. On repeat radiographs, computed tomography (CT) scan, and MR images, tumor enlargement with cystic findings typical of simple bone cyst were documented. Diagnostic aspiration of the lesion was firstly done, revealing straw-colored fluid. The patient then underwent intralesional curettage with alpha-tricalcium phosphate cement reconstruction of the lytic defect. No perioperative complications were incurred, and on latest follow-up at 3 years postoperatively, Musculoskeletal Tumor Society (MSTS) and visual analog scale (VAS) pain scores were 30/30 and 0/10, respectively. CONCLUSIONS: The authors believe their report provides support to a possible association to trauma of simple bone cysts occurring in the adult population with closed physes and suggest this subset of patients may require a different treatment approach from that for juvenile simple bone cysts.

Traumatic bone cyst of an anterior mandible with previous symphyseal fracture in a pediatric patient: a rare finding and etiopathologic correlation.

Traumatic bone cysts (TBCs) are uncommon intraosseous lesions, classified as pseudocysts because they lack an epithelial membrane lining. The etiology of a pseudocyst has not been determined. Various hypotheses have been put forward to explain its pathogenesis, of which the traumatic-hemorrhagic theory is the most commonly accepted. Minor trauma, insufficient to cause fracture or iatrogenic injury, is commonly implicated as the stimulus initiating cyst formation. A TBC presenting after jaw fracture has been rarely reported in the literature. This article presents a case of a TBC of the anterior mandible in a child with a previous history of trauma and fracture of the symphysis. The article also reviews the literature to corroborate the possible role of major trauma in the pathogenesis of TBC.

Comparison of titanium elastic intramedullary nailing versus injection of bone marrow in treatment of simple bone cysts in children: a retrospective study.

BACKGROUND: Simple bone cysts are common benign lytic bone lesions in children. The main goals of treatment for bone cysts are to prevent pathological fractures, support the healing process, and prevent recurrence. This retrospective study compared fixation with titanium elastic intramedullary nailing (TEN) versus aspiration and injection of autogenous bone marrow (ABM) for the treatment of simple bone cysts in children. METHODS: Forty-six patients (mean follow-up, 62 months; range, 34-71 months) who presented with bone cysts (30 in the humerus, 16 in the femur) from January 2006 to December 2012 were retrospectively evaluated. Patients were treated with either TEN or ABM injection. Radiographs were evaluated according to previously established criteria. Clinical evaluations of pain, infection, additional fractures, and range of motion were performed. RESULTS: After treatment, all patients were pain-free and had normal range of motion in adjacent joints. In the ABM group, 14 (60.9 %) bone cysts completely healed, six (26.1 %) healed with small residuals after two injections, and three (13.0 %) recurred. In the TEN group, 16 (69.6 %) bone cysts completely healed, four (17.4 %) healed with small residuals, and three (13.0 %) recurred. There were no significant differences in radiographic outcomes between groups at the final follow-up (P > 0.05). Three patients developed skin irritation as a result of the nail ends. Additional fractures occurred in four patients who underwent ABM injection and in two patients who underwent TEN. No significant associations were found between pathological fractures and cyst activity, location, or treatment outcomes in the patients studied. CONCLUSIONS: Both TEN and ABM injection are safe and effective treatment for bone cysts. ABM injection promotes osteogenic differentiation of bone marrow stromal cells; multiple injections can reduce the likelihood of recurrence. TEN stabilizes the affected bone and thus allows early limb mobilization. It also reduces pressure in the capsule wall by continuous decompression to promote cyst healing. ABM injections can be used to treat cyst recurrence after previous TEN, with favorable results.

Florid osseous dysplasia associated with multiple simple bone cysts: a patient with 22 years of follow-up.

Florid osseous dysplasia (FOD) has been described as a condition that typically affects the jaws of middle-aged women of African descent and usually presents as multiple radiopaque masses distributed throughout the jaws. The diagnosis is generally based on clinical and radiographic presentation, often involving various regions of the jaws without evident bone expansion. This article describes the course of FOD in a 27-year-old African-American woman during 22 years of follow-up, emphasizing the dynamic radiographic characteristics of this entity and unusual co-occurrence with multiple simple bone cysts. These data reinforce the importance of long-term follow-up in patients diagnosed with FOD.

Treatment of Unicameral Bone Cysts of the Calcaneus: A Systematic Review.

The calcaneus is the most common tarsal affected by unicameral bone cysts (UBCs); however, the treatment of calcaneal UBCs remains controversial. The purpose of the present systematic review was to evaluate the treatment modalities for calcaneal UBCs. A systematic review was performed using clinical studies of calcaneal UBCs with a minimum of 1 year of follow-up and level I to IV evidence. Ten studies with 171 patients (181 cysts) were selected. Heel pain and radiographic cyst consolidation were the primary outcomes. A series of Z tests were used to compare the outcomes in the nonoperative and operative groups, cannulated screw and bone augmentation groups, and autografting and allografting groups. All patients treated with open curettage and bone augmentation had significant improvements in heel pain (p < .001). Only 1.1% ± 1.0% of the cysts treated conservatively had healed on radiographs compared with 93.0% ± 13.0% of the cysts after surgery (p < .001). A greater percentage of patients treated with bone augmentation had preoperative heel pain and resolution of that pain than did patients treated with cannulated screws (p < .001). Autografting had a significantly greater percentage of radiographic cyst consolidation than did allografting (97.4% ± 11.1% versus 85.1% ± 15.8%, p < .001, Z = 3.5). Objective outcomes data on calcaneal UBCs are relatively sparse. The results of the present review suggest that open curettage with autograft bone augmentation is the most effective procedure. We would encourage future comparative clinical studies to elucidate differences in UBC treatment modalities.

Facial Cellulitis and Skin Abscess: A Case of a Simple Bone Cyst in the Mandibular Bone.

Cellulitis, abscess, or both are among the most common skin and soft tissue infections. Typically, cellulitis arises due to bacterial penetration through breaches in the skin's protective barrier. However, in cases of facial cellulitis, it is necessary to consider not only the breakdown of the skin barrier but also to differentiate odontogenic cellulitis. A prompt and accurate diagnosis of facial infections stemming from dental issues, coupled with the administration of antibiotics and dental interventions, played a crucial role in resolving this condition. Odontogenic cellulitis often develops as a result of dental caries. However, we experienced a case of odontogenic cellulitis and skin abscess occurring due to a simple bone cyst in the mandible, even in the absence of dental caries. Proper imaging examinations are crucial for diagnosis.

Differential Diagnosis of OKC and SBC on Panoramic Radiographs: Leveraging Deep Learning Algorithms.

This study aims to determine whether it can distinguish odontogenic keratocyst (OKC) and simple bone cyst (SBC) based solely on preoperative panoramic radiographs through a deep learning algorithm. (1) Methods: We conducted a retrospective analysis of patient data from January 2018 to December 2022 at Pusan National University Dental Hospital. This study included 63 cases of OKC confirmed by histological examination after surgical excision and 125 cases of SBC that underwent surgical curettage. All panoramic radiographs were obtained utilizing the Proline XC system (Planmeca Co., Helsinki, Finland), which already had diagnostic data on them. The panoramic images were cut into 299 × 299 cropped sizes and divided into 80% training and 20% validation data sets for 5-fold cross-validation. Inception-ResNet-V2 system was adopted to train for OKC and SBC discrimination. (2) Results: The classification network for diagnostic performance evaluation achieved 0.829 accuracy, 0.800 precision, 0.615 recall, and a 0.695 F1 score. (4) Conclusions: The deep learning algorithm demonstrated notable accuracy in distinguishing OKC from SBC, facilitated by CAM visualization. This progress is expected to become an essential resource for clinicians, improving diagnostic and treatment outcomes.

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.

Acquired Simple Bone Cyst Associated With Lumbar Spinal Canal Stenosis Progression: A Case Report.

A simple bone cyst (SBC) in the posterior lumbar bone structure is very rare. Here, we report a case of SBC at the L5 lumbar lamina with venous obstruction associated with ligamentum flavum thickening. A 59-year-old woman presented with intermittent claudication due to low back pain and bilateral sciatica. A lumbar MRI showed L4-5 lumbar spinal canal stenosis and a T2-weighted image hyperintense lesion in the L5 lamina. Imaging four years earlier showed no lesions in the L5 lamina. Her symptoms improved after lumbar decompression surgery. The L5 lamina lesion was SBC, leading to a diagnosis of venous infarction. The involvement of neovascularization in the mechanism of degenerative hypertrophy in the ligamentum flavum was suggested. In this case, increased venous perfusion and venous obstruction were involved in the formation of the bone cyst.