Simple bone cysts (SBCs) are the most common osteolytic lesions in children, often leading to pathological fractures of non-weight-bearing bones. These benign tumors primarily arise in the proximal humerus, femur, or calcaneus. The cystic cavity is filled with serous or serosanguineous fluid and lined by a thin fibrovascular connective tissue membrane. The etiological factors include disturbances in bone growth, local venous obstruction, synovial origin disorders, and genetic predispositions. SBCs are most frequently observed in individuals from birth to 20 years of age. The report presented a case of a 12-year-old male patient who was admitted to the hospital with a history of a mass on his left upper arm. The mass had an acute onset and gradually progressed to its current size over three to four weeks, after which it became nonprogressive. The patient had been healthy until the age of four, after which he experienced frequent fractures of the left arm following trivial trauma. Multiple traumas led to the gradual formation of a diffuse mass over the upper part of the humerus. Radiological imaging modalities, such as X-ray and magnetic resonance imaging, are crucial in diagnosing bone cysts and evaluating their clinical conditions. Treatment can involve the injection of bone marrow or steroids into the cyst to facilitate the healing process.

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.

OBJECTIVE: 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.
CONCLUSIONS: 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.

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.

Simple bone cysts (SBCs) are benign cavitary lesions that most commonly affect adolescent males in the first 2 decades of life. They are mainly asymptomatic but can manifest with pain or pathological fractures. Despite numerous proposed methods for managing calcaneal SBCs, the optimal approach toward these lesions remains controversial. Herein, we report a case of a 16-year-old girl with a calcaneal SBC. On local examination, tenderness was the only noteworthy sign. In an outpatient setting, under conscious sedation, 2 interosseous needles were simultaneously inserted into the cyst under the guidance of CT fluoroscopy. Without aspiration, a radiopaque bone cement mixture was injected into the cyst from 1 needle until serosanguineous fluid efflux from the second needle ceased. Over a 2-year follow-up period, the patient recovered without any complications. This novel technique has the potential to be used as a feasible and minimally invasive approach in the management of symptomatic unicameral calcaneal bone cysts.

Simple bone cysts (SBCs) and intraosseous lipoma (IOL) of the calcaneus are rare tumor entities that are primarily diagnosed due to unspecific heel pain, incidental findings, or rarely due to pathological fractures. Compared to traditional open tumor resections, endoscopic resection of these benign tumors aims to minimize surgical morbidity and maximize surgical efficiency without compromising safety. Grafting is regularly performed to reduce the risk of recurrence and stimulate osseous consolidation of the lytic lesion. As the incidence is low and treatment strategies are heterogeneous, there is no clear consensus for the treatment of simple cysts or intraosseous lipomas of the calcaneus. The objectives of this study are (a) to present medium to long-term results after endoscopic resection and grafting with allogenic cancellous bone or bioresorbable hydroxyapatite and calcium sulfate cement, and (b) to add further evidence to the discussion of whether calcaneal SBC and IOL are the same entity at different developmental stages. Between 2012 and 2019, a total of 25 benign bone tumors consisting of 17 SBCs and 8 IOLs were treated by A.T. with endoscopic resection and grafting, comprising the largest cohort to date. For grafting, 12 patients received allogenic cancellous bone (group A) and 13 patients received injectable bone substitute (group B). Pre- and postoperative imaging using plain X-rays and MRI was retrospectively analyzed with a mean follow-up time of 24.5 months to assess tumor size, osseous consolidation (modified Neer classification), and tumor recurrence. A retrospective chart analysis focusing on adverse intra- and perioperative events and other complications associated with the surgical procedure was performed using the modified Clavien-Dindo classification (CD1-3). A total of 12/13 cases with allogenic bone grafting showed a Neer Type 1 osseous healing of the tumorous lesion after endoscopic resection, whereas only 5/11 cases with injectable bone substitute showed sufficient healing (types 1 and 2). There were three recurrent cysts (Neer 4) and two persistent cysts (Neer 3) after using injectable bone substitute. Two CD1 complications were observed in group A (prolonged wound drainage, sural neuritis) and eight complications were observed in group B (6× CD1, 2× CD3). At least two IOLs diagnosed preoperatively using MRI were ultimately identified as SBCs upon histopathologic examination. Allogenic cancellous bone grafting after endoscopic resection of calcaneal SBC or IOL showed a very low rate of complications and no tumor recurrence in our series. On the other hand, depending on the material used, injectable bone substitute showed a high rate of \"white-out\" (excessive drainage), resulting in multiple complications such as prolonged wound healing, insufficient permanent defect filling, recurrence, and revision surgery. Over time, calcaneal SBC may transform into IOL, exhibiting distinct features of both entities simultaneously during ossoscopy and histopathological analysis.

Benign tumours comprise the majority of primary vertebral tumours, and these are often found incidentally on imaging. Nonetheless, accurate diagnosis of these benign lesions is crucial, in order to avoid misdiagnosis as more ominous malignant lesions or infection. Furthermore, some of these tumours, despite their benign nature, can have localised effects on the spine including neural compromise, or can be locally aggressive, thus necessitating active management. Haemangiomas and osteomas (enostosis) are the commonest benign tumours encountered. Others include osteoid osteoma, osteoblastoma, fibrous dysplasia, osteochondroma, chondroblastoma, haemangioma, simple bone cysts, aneurysmal bone cysts, giant cell tumours, eosinophilic granuloma and notochordal rests. The majority of lesions are asymptomatic; however, locally aggressive lesions (such as aneurysmal bone cysts or giant cell tumours) can present with nonspecific symptoms, such as back pain, neurological deficits and spinal instability, which may be indistinguishable from more commonly encountered mechanical back pain or malignant lesions including metastases. Hence, imaging, including radiography, computed tomography (CT) and magnetic resonance imaging (MRI), plays a critical role in diagnosis. Generally, most incidental or asymptomatic regions are conservatively managed or may not require any follow-up, while symptomatic or locally aggressive lesions warrant active interventions, which include surgical resection or percutaneous treatment techniques. Due to advances in interventional radiology techniques in recent years, percutaneous minimally invasive techniques such as radiofrequency ablation, sclerotherapy and cryoablation have played an increasing role in the management of these tumours with favourable outcomes. The different types of primary benign vertebral tumours will be discussed in this article with an emphasis on pertinent imaging features.

Cemento-osseous dysplasia (COD) is a non-neoplastic, usually asymptomatic condition characterized by the presence of amorphous cement-like calcifications located exclusively in the tooth-bearing regions of the jawbone. Simple bone cysts (SBCs) of the jaws are benign intraosseous cavities, empty or filled with serous, serohematic, or blood fluid. They are characterized by the absence of an epithelial lining. COD and SBCs are two distinct lesions of the jaws that have long been described separately in the literature; however, their co-occurrence remains rare and only a few cases have been reported illustrating this relationship. This association can be considered as a distinct entity since it presents specific epidemiological, clinical, and radiological data. The aim of this article was to report a new case of association between COD and SBC by illustrating a florid COD formation in mandibular SBC detected in a 31-year-old patient followed over a period of 11 years.

OBJECTIVE: 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.
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.
CONCLUSIONS: 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.

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.