Controversies in orthopaedic oncology

Chondrosarcoma is the second most common surgically treated primary bone sarcoma. Despite a large number of scientific papers in the literature, there is still significant controversy about diagnostics, treatment of the primary tumour, subtypes, and complications. Therefore, consensus on its day-to-day treatment decisions is needed. In January 2024, the Birmingham Orthopaedic Oncology Meeting (BOOM) attempted to gain global consensus from 300 delegates from over 50 countries. The meeting focused on these critical areas and aimed to generate consensus statements based on evidence amalgamation and expert opinion from diverse geographical regions. In parallel, periprosthetic joint infection (PJI) in oncological reconstructions poses unique challenges due to factors such as adjuvant treatments, large exposures, and the complexity of surgery. The meeting debated two-stage revisions, antibiotic prophylaxis, managing acute PJI in patients undergoing chemotherapy, and defining the best strategies for wound management and allograft reconstruction. The objectives of the meeting extended beyond resolving immediate controversies. It sought to foster global collaboration among specialists attending the meeting, and to encourage future research projects to address unsolved dilemmas. By highlighting areas of disagreement and promoting collaborative research endeavours, this initiative aims to enhance treatment standards and potentially improve outcomes for patients globally. This paper sets out some of the controversies and questions that were debated in the meeting.

Optimal design of bone tumor ablation device based on radio frequency heating using Taguchi method

This study investigated the optimal design of a radio-frequency (RF) bone tumor ablation device to achieve uniform heating. In a previous study, we confirmed the feasibility of this device, which could heat all regions of the bone to 70 °C or higher and maintain this temperature for more than 30 min. However, the temperature in each part was non-uniform. To address this issue, the shape of the electrode must be modified to create a uniform electric field. The design of the electrode was optimized to reduce temperature deviations. It is difficult to analytically model the relationship between the shape of the electrode and the electric field. The electrode's design factors were fine-tuned using the Taguchi method, a robust design of experiment approach. The primary objective in this optimization was to maximize the signal-to-noise ratio for temperature in each component, aiming for higher values. After four trials, the signal-to-noise ratio increased in comparison with the initial modified shape from 68.3 to 98.6. The experiment was conducted using an experimental device fabricated using the optimal design factors. In comparison to the previous experiment, the temperature standard deviation per part over time decreased from 10.56 °C 4.28 °C. The experimental results demonstrated the validity of the proposed optimal design approach. In the future, the proposed method can be used to optimize the design factors when a product is advanced to develop a device that can be applied to the human body.

Can DNA Methylation Profiling Classify Histologic Subtypes and Grades in Soft Tissue Sarcoma?

BACKGROUND

A clear classification of the subtype and grade of soft tissue sarcoma is important for predicting prognosis and establishing treatment strategies. However, the rarity and heterogeneity of these tumors often make diagnosis difficult. In addition, it remains challenging to predict the response to chemotherapy and prognosis. Thus, we need a new method to help diagnose soft tissue sarcomas and determine treatment strategies in conjunction with traditional methods. Genetic alterations can be found in some subtypes of soft tissue sarcoma, but many other types show dysregulated gene expression attributed to epigenetic changes, such as DNA methylation status. However, research on DNA methylation profiles in soft tissue sarcoma is still insufficient to provide information to assist in diagnosis and therapeutic decisions.

QUESTIONS/PURPOSES

(1) Do DNA methylation profiles differ between normal tissue and soft tissue sarcoma? (2) Do DNA methylation profiles vary between different histologic subtypes of soft tissue sarcoma? (3) Do DNA methylation profiles differ based on tumor grade?

METHODS

Between January 2019 and December 2022, we treated 85 patients for soft tissue sarcomas. We considered patients whose specimens were approved for pilot research by the Human Biobank of St. Vincent's Hospital, The Catholic University of Korea, as potentially eligible. Based on this, 41% (35 patients) were eligible; 1% (one patient) was excluded because of gender mismatch between clinical and genetic data after controlling for data quality. Finally, 39 specimens (34 soft tissue sarcomas and five normal samples) were included from 34 patients who had clinical data. All tissue samples were collected intraoperatively. The five normal tissue samples were from muscle tissues. There were 20 female patients and 14 male patients, with a median age of 58 years (range 19 to 82 years). Genomic DNA was extracted from frozen tissue, and DNA methylation profiles were obtained. Genomic annotation of DNA methylation sites and hierarchical cluster analysis were performed to interpret results from DNA methylation profiling. A t-test was used to analyze different methylation probes. Benjamini-Hochberg-adjusted p value calculations were used to account for bias resulting from evaluating thousands of methylation sites.

RESULTS

The most common histologic subtypes were liposarcoma (n = 10) and leiomyosarcoma (n = 9). The tumor grade was Fédération Nationale des Centres de Lutte Contre Le Cancer Grades 1, 2, and 3 in 3, 15, and 16 patients, respectively. DNA methylation profiling demonstrated differences between soft tissue sarcoma and normal tissue as 21,188 cytosine-phosphate-guanine sites. Despite the small number of samples, 72 of these sites showed an adjusted p value of < 0.000001, suggesting a low probability of statistical errors. Among the 72 sites, 70 exhibited a hypermethylation pattern in soft tissue sarcoma, with only two sites showing a hypomethylation pattern. Thirty of 34 soft tissue sarcomas were distinguished from normal samples using hierarchical cluster analysis. There was a different methylation pattern between leiomyosarcoma and liposarcoma at 7445 sites. Using the data, hierarchical clustering analysis showed that liposarcoma was distinguished from leiomyosarcoma. When we used the same approach and included other subtypes with three or more samples, only leiomyosarcoma and myxofibrosarcoma were separated from the other subtypes, while liposarcoma and alveolar soft-part sarcoma were mixed with the others. When comparing DNA methylation profiles between low-grade (Grade 1) and high-grade (Grades 2 and 3) soft tissue sarcomas, a difference in methylation pattern was observed at 144 cytosine-phosphate-guanine sites. Among these, 132 cytosine-phosphate-guanine sites exhibited hypermethylation in the high-grade group compared with the low-grade group. Hierarchical clustering analysis showed a division into two groups, with most high-grade sarcomas (28 of 31) separated from the low-grade group and few (3 out of 31) clustered together with the low-grade group. However, three high-grade soft tissue sarcomas were grouped with the Grade 1 cluster, and all of these sarcomas were Grade 2. When comparing Grades 1 and 2 to Grade 3, Grade 3 tumors were separated from Grades 1 and 2.

CONCLUSION

We observed a different DNA methylation pattern between soft tissue sarcomas and normal tissues. Liposarcoma was distinguished from leiomyosarcoma using methylation profiling. High-grade soft tissue sarcoma samples showed a hypermethylation pattern compared with low-grade ones. Our findings indicate the need for research using methylation profiling to better understand the diverse biological characteristics of soft tissue sarcoma. Such research should include studies with sufficient samples and a variety of subtypes, as well as analyses of the expression and function of related genes. Additionally, efforts to link this research with clinical data related to treatment and prognosis are necessary.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Histologic Heterogeneity of Chondrosarcoma Reflected on Bone SPECT/CT

ABSTRACT

Chondrosarcomas are a heterogeneous group of cartilage-forming tumors. The tumor is graded on areas demonstrating the highest grade. A 71-year-old man underwent bone SPECT/CT to investigate a tumorous lesion on his right femur. Correlating with the pathological findings, the high-grade area showed higher uptake in bone SPECT/CT. This case suggests that bone SPECT/CT could aid in selecting an optimal biopsy site for diagnosis, and determining the proper treatment of patients with suspected chondroid tumors.

Feasibility of a Novel In-situ Local Tumor Ablation and Recycling Machine Based on Radiofrequency Dielectric Heating: In-depth Review on Research Background and Preliminary Report of an Experimental Study

Background

In bone sarcomas, chemotherapy has improved the prognosis with advances in diagnostic and surgical technologies, which has led to attempts to save limbs. As early detection and multidisciplinary treatment have improved the survival rate, curative surgery is considered for selected patients with metastatic bone carcinomas. Limb salvage procedures may vary in relation to the reconstruction method, which is accompanied by different complications. To overcome them, we devised a novel concept, in-situ local tumor ablation and recycling machine based on radiofrequency (RF)-induced heating and intended experiments to demonstrate its feasibility.

Methods

The fresh femurs of 6-month-old pigs were used after removing the epiphyses; the distal parts were placed in a heating chamber. Fiber-optic temperature sensors were inserted in the metaphysis, meta-diaphysis, and diaphysis. Temperatures were measured six times each during heating at 27.12 MHz at various powers. Additionally, the compressive and bending stiffnesses were measured six times each for the unprocessed, RF-treated, and pasteurized bones, and the results were compared.

Results

Under 200 W power output, the temperatures at all measurement sites reached 70 ℃ or higher in 6 minutes, and the temperatures were maintained. The median compressive stiffness of RF-heated bones was 79.2% higher than that of pasteurized bones, but the difference was statistically insignificant. The median bending stiffness of RF-heated bones was approximately 66.3% of that of unprocessed bones, which was 20% higher than that of pasteurized bones.

Conclusions

The feasibility to rapidly attain and maintain temperatures for tumor ablation is shown, which favorably preserves bone stiffness through the in-situ local tumor ablation and recycling based on RF heating. The problem of nonuniform temperature distribution might be solved by an optimal design determined from simulation research and additional experiments.

Current Treatment Concepts for Extra-Abdominal Desmoid-Type Fibromatosis: A Narrative Review

Extra-abdominal desmoid-type fibromatosis (EADTF) is a rare neoplastic condition of monoclonal fibroblastic proliferation characterized by local aggressiveness with a distinct tendency to recur. Although EADTF is a benign disease entity, these tumors have a tendency to infiltrate surrounding normal tissues, making it difficult to completely eliminate them without adjacent healthy tissue injury. Surgical excision of these locally aggressive tumors without clear resection margins often leads to local recurrence. The aim of this thorough review was to assess the current treatment concepts for these rare tumors. A comprehensive search of articles published in the Cochrane Library, MEDLINE (PubMed), and EMBASE databases between January 2008 and February 2023 was conducted. Surgical intervention is no longer the first-line approach for most cases; instead, strategies like active surveillance or systemic therapies are used as initial treatment options. With the exception of EADTFs situated near vital structures, a minimum of 6-12 months of active surveillance is currently advocated for, during which some disease progression may be considered acceptable. Non-surgical interventions such as radiation or cryoablation may be employed in certain patients to achieve local control. The currently preferred systemic treatment options include tyrosine kinase inhibitors, low-dose chemotherapy, and gamma-secretase inhibitors, while hormone therapy is not advised. Nonsteroidal anti-inflammatory drugs are utilized primarily for pain management.

Development and Validation of a Convolutional Neural Network Model to Predict a Pathologic Fracture in the Proximal Femur Using Abdomen and Pelvis CT Images of Patients With Advanced Cancer

BACKGROUND

Improvement in survival in patients with advanced cancer is accompanied by an increased probability of bone metastasis and related pathologic fractures (especially in the proximal femur). The few systems proposed and used to diagnose impending fractures owing to metastasis and to ultimately prevent future fractures have practical limitations; thus, novel screening tools are essential. A CT scan of the abdomen and pelvis is a standard modality for staging and follow-up in patients with cancer, and radiologic assessments of the proximal femur are possible with CT-based digitally reconstructed radiographs. Deep-learning models, such as convolutional neural networks (CNNs), may be able to predict pathologic fractures from digitally reconstructed radiographs, but to our knowledge, they have not been tested for this application.

QUESTIONS/PURPOSES

(1) How accurate is a CNN model for predicting a pathologic fracture in a proximal femur with metastasis using digitally reconstructed radiographs of the abdomen and pelvis CT images in patients with advanced cancer? (2) Do CNN models perform better than clinicians with varying backgrounds and experience levels in predicting a pathologic fracture on abdomen and pelvis CT images without any knowledge of the patients' histories, except for metastasis in the proximal femur?

METHODS

A total of 392 patients received radiation treatment of the proximal femur at three hospitals from January 2011 to December 2021. The patients had 2945 CT scans of the abdomen and pelvis for systemic evaluation and follow-up in relation to their primary cancer. In 33% of the CT scans (974), it was impossible to identify whether a pathologic fracture developed within 3 months after each CT image was acquired, and these were excluded. Finally, 1971 cases with a mean age of 59 ± 12 years were included in this study. Pathologic fractures developed within 3 months after CT in 3% (60 of 1971) of cases. A total of 47% (936 of 1971) were women. Sixty cases had an established pathologic fracture within 3 months after each CT scan, and another group of 1911 cases had no established pathologic fracture within 3 months after CT scan. The mean age of the cases in the former and latter groups was 64 ± 11 years and 59 ± 12 years, respectively, and 32% (19 of 60) and 53% (1016 of 1911) of cases, respectively, were female. Digitally reconstructed radiographs were generated with perspective projections of three-dimensional CT volumes onto two-dimensional planes. Then, 1557 images from one hospital were used for a training set. To verify that the deep-learning models could consistently operate even in hospitals with a different medical environment, 414 images from other hospitals were used for external validation. The number of images in the groups with and without a pathologic fracture within 3 months after each CT scan increased from 1911 to 22,932 and from 60 to 720, respectively, using data augmentation methods that are known to be an effective way to boost the performance of deep-learning models. Three CNNs (VGG16, ResNet50, and DenseNet121) were fine-tuned using digitally reconstructed radiographs. For performance measures, the area under the receiver operating characteristic curve, accuracy, sensitivity, specificity, precision, and F1 score were determined. The area under the receiver operating characteristic curve was used to evaluate three CNN models mainly, and the optimal accuracy, sensitivity, and specificity were calculated using the Youden J statistic. Accuracy refers to the proportion of fractures in the groups with and without a pathologic fracture within 3 months after each CT scan that were accurately predicted by the CNN model. Sensitivity and specificity represent the proportion of accurately predicted fractures among those with and without a pathologic fracture within 3 months after each CT scan, respectively. Precision is a measure of how few false-positives the model produces. The F1 score is a harmonic mean of sensitivity and precision, which have a tradeoff relationship. Gradient-weighted class activation mapping images were created to check whether the CNN model correctly focused on potential pathologic fracture regions. The CNN model with the best performance was compared with the performance of clinicians.

RESULTS

DenseNet121 showed the best performance in identifying pathologic fractures; the area under the receiver operating characteristic curve for DenseNet121 was larger than those for VGG16 (0.77 ± 0.07 [95% CI 0.75 to 0.79] versus 0.71 ± 0.08 [95% CI 0.69 to 0.73]; p = 0.001) and ResNet50 (0.77 ± 0.07 [95% CI 0.75 to 0.79] versus 0.72 ± 0.09 [95% CI 0.69 to 0.74]; p = 0.001). Specifically, DenseNet121 scored the highest in sensitivity (0.22 ± 0.07 [95% CI 0.20 to 0.24]), precision (0.72 ± 0.19 [95% CI 0.67 to 0.77]), and F1 score (0.34 ± 0.10 [95% CI 0.31 to 0.37]), and it focused accurately on the region with the expected pathologic fracture. Further, DenseNet121 was less likely than clinicians to mispredict cases in which there was no pathologic fracture than cases in which there was a fracture; the performance of DenseNet121 was better than clinician performance in terms of specificity (0.98 ± 0.01 [95% CI 0.98 to 0.99] versus 0.86 ± 0.09 [95% CI 0.81 to 0.91]; p = 0.01), precision (0.72 ± 0.19 [95% CI 0.67 to 0.77] versus 0.11 ± 0.10 [95% CI 0.05 to 0.17]; p = 0.0001), and F1 score (0.34 ± 0.10 [95% CI 0.31 to 0.37] versus 0.17 ± 0.15 [95% CI 0.08 to 0.26]; p = 0.0001).

CONCLUSION

CNN models may be able to accurately predict impending pathologic fractures from digitally reconstructed radiographs of the abdomen and pelvis CT images that clinicians may not anticipate; this can assist medical, radiation, and orthopaedic oncologists clinically. To achieve better performance, ensemble-learning models using knowledge of the patients' histories should be developed and validated. The code for our model is publicly available online at https://github.com/taehoonko/CNN_path_fx_prediction .

LEVEL OF EVIDENCE

Level III, diagnostic study.

SPECT/CT Radiomics for Differentiating between Enchondroma and Grade I Chondrosarcoma

This study was performed to assess the value of SPECT/CT radiomics parameters in differentiating enchondroma and atypical cartilaginous tumors (ACTs) located in the long bones. Quantitative HDP SPECT/CT data of 49 patients with enchondromas or ACTs in the long bones were retrospectively reviewed. Patients were randomly split into training (n = 32) and test (n = 17) data, and SPECT/CT radiomics parameters were extracted. In training data, LASSO was employed for feature reduction. Selected parameters were compared with classic quantitative parameters for the prediction of diagnosis. Significant parameters from training data were again tested in the test data. A total of 12 (37.5%) and 6 (35.2%) patients were diagnosed as ACTs in training and test data, respectively. LASSO regression selected two radiomics features, zone-length non-uniformity for zone (ZLNUGLZLM) and coarseness for neighborhood grey-level difference (CoarsenessNGLDM). Multivariate analysis revealed higher ZLNUGLZLM as the only significant independent factor for the prediction of ACTs, with sensitivity and specificity of 85.0% and 58.3%, respectively, with a cut-off value of 191.26. In test data, higher ZLNUGLZLM was again associated with the diagnosis of ACTs, with sensitivity and specificity of 83.3% and 90.9%, respectively. HDP SPECT/CT radiomics may provide added value for differentiating between enchondromas and ACTs.

Fracture Liaison Service in Korea: 2022 Position Statement of the Korean Society for Bone and Mineral Research

Osteoporosis and osteoporotic fractures cause socioeconomic concerns, and medical system and policies appear insufficient to prepare for these issues in Korea, where the older adult population is rapidly increasing. Many countries around the world are already responding to osteoporosis and osteoporotic fractures by adopting fracture liaison service (FLS), and such an attempt has only begun in Korea. In this article, we introduce the operation methods for institutions implementing FLS and characteristics of services, and activities of the FLS Committee for FLS implementation in the Korean Society for Bone and Mineral Research. In addition, we hope that the current position statement will contribute to the implementation of FLS in Korea and impel policy changes to enable a multidisciplinary and integrated FLS operated under the medical system.

Secondary Malignancy in Giant Cell Tumor: A Single-Center Study

Giant cell tumor of bone (GCTB) undergoes a sarcomatous transformation. Secondary malignancy in giant cell tumor (MGCT) is associated with radiotherapy and has a dismal prognosis. We reviewed medical records to investigate the clinicopathological characteristics and prognosis of MGCT patients. The enrollment criterion was high-grade spindle-cell sarcoma, which developed at the site of prior GCTB treatment. Twelve patients were analyzed: six females and six males. The median age was 42.5 years. Benign recurrence occurred in five GCTB patients not treated with radiotherapy. No pulmonary implants were observed. The median latency to the malignant transformation was 63 months. Nine patients were AJCC stage IIB, and three were stage IVA. The median follow-up period after malignant transformation was 62.5 months. Five patients developed local recurrence, and six had distant metastasis. Five-year overall recurrence and metastasis-free survival rates were 61.9%, 66.7%, and 58.3%, respectively. Initial metastasis was a predictive factor for overall survival. Benign local recurrence of GCTB was also a negative factor for metastasis-free survival of MGCT patients. Differences in overall survival according to benign recurrence also showed a tendency toward significance. In our series, secondary MGCT did not occur after radiotherapy. The prognosis was better than previous findings. Benign recurrence of GCTB could reflect the prognosis of MGCT.

Sarcomas in Teachers Using Three-Dimensional Printers: A Report of Three Patients and Literature Review

Background

While low-cost, small-scale, desktop three-dimensional (3D) printers are gaining popularity in the education sector, some studies have reported harmful emissions of particles and volatile organic compounds during the fused deposition modeling (FDM) process, posing a potential health risk. Sarcomas are rare tumors, constituting a group of diverse rare malignant tumors. While some genetic and environmental factors contribute to the development of sarcomas, most cases are idiopathic and sporadic.

Methods

We secured the medical records and statements about work environment from teachers diagnosed with sarcomas after frequent use of 3D printers in high schools, reviewed the cases, and described them in narrative format. Furthermore, popularization of FDM 3D printers, worrisome emissions released during the printing process, and related precautions and countermeasures were discussed through literature review.

Results

Exceptionally, the cases of sarcomas, such as Ewing’s sarcoma, malignant peripheral nerve sheath tumor, and well-differentiated liposarcoma, arose in a common specific condition. All the teachers regularly operated 3D printers in poorly ventilated spaces for at least 2 years. They had no past or family history of relevant diseases.

Conclusions

We first reported three cases of sarcoma in teachers who used 3D printers in poorly ventilated conditions. Although a relationship between the use of 3D printers and the development of sarcomas has not been determined yet, it is important to come up with measures to protect teachers and students using 3D printers from the potential hazard.

Germline Mutations for Novel Candidate Predisposition Genes in Sporadic Schwannomatosis

BACKGROUND

Schwannomatosis is a late-onset tumor predisposition syndrome associated with the development of many different types of malignancies. A relevant genetic mechanism can be explained by three mutational events. The first-hit mutation is a germline mutation, and the SMARCB1 mutation on chromosome 22 is the most well-known genetic abnormality in patients with schwannomatosis. LZTR1 is another major predisposing gene in 22q-related schwannomatosis that lacks SMARCB1 variants. Although these two variants account for the occurrence of most familiar schwannomatoses, the genetic causes of sporadic schwannomatosis for the most part remain unknown. Therefore, current molecular diagnostic criteria cannot completely explain the basis of this disease. The common genetic background between schwannomatosis and other related malignant tumors is also unclear. Moreover, it is not easy to explain various clinical manifestations by only two known mutations. QUESTION/PURPOSES: (1) Are there important sequences outside the SMARCB1 or LZTR1 region on chromosome 22 that might carry a first-hit mutational predisposition to sporadic schwannomatosis? Or are there alternative evolutionarily conserved loci that might carry a first-hit mutational predisposition? (2) Is the age of disease onset associated to such genetic variants?

METHODS

This study was a retrospective chart review and prospective genetic study on patients with schwannomatosis who were treated surgically. The clinical criteria to diagnose schwannomatosis were as follows: (1) histologically proven nonvestibular schwannomas; (2) no evidence of vestibular schwannomas on 3-mm brain MRI. A total of 21 patients were treated between March 2006 and June 2015. Since nine patients did not visit the outpatient clinic during the recruitment period, we obtained blood samples from 12 patients with schwannomatosis for a genetic analysis. After two patients were excluded because of their family history of schwannomatosis, genetic analyses were finally performed on 10 patients. Then, those with NF2, SMARCB1 or LZTR1 variants were screened by whole exome sequencing. All 10 patients passed our screening strategy. There were eight men and two women, with a median (range) age of 43 years (24 to 66) at the time of diagnosis. To select candidate genes, common ethnic variants and frequent mutations in in-house exome sequencing data were removed to exclude the population-specific polymorphisms not found in other population and to generalize the findings. Frameshift, nonsense, and splice-site variants were deemed pathogenic. Missense variants were classified as potentially pathogenic, variants of uncertain significance, or benign using in silico (via computer simulation) prediction algorithms, Sorting Intolerant From Tolerant (SIFT), Polymorphism Phenotyping v2 (PolyPhen-2), and Combined Annotation Dependent Depletion (CADD). A variant was considered potentially pathogenic if two or more algorithms predicted the variant to be damaging and benign if none considered it damaging. Then, potentially pathogenic variants only in the genes associated with cancer-predisposition or DNA damage repair were classified as the pathogenic candidate variants of sporadic schwannomatosis. The predictions for pathogenic candidate variants were checked again on Clinical Interpretation of Genetic Variants (InterVar) based on the American College of Medical Genetics guidelines and validated against Mendelian clinically applicable pathogenicity scores (M-CAP scores).

RESULTS

We detected 26 variants; 13 variants across 10 genes were predicted to be pathogenic and found in seven patients, two each in ARID1A, PTCH2, and NOTCH2 and one each in MSH6, ALPK2, MGMT, NOTCH1, CIC, TSC2, and CDKN2A. One frameshift deletion in PTCH2 met the criteria for pathogenic or likely pathogenic classification, as recommended by the American College of Medical Genetics guidelines. Six missense mutations were classified as possibly pathogenic variants based on M-CAP scores. Four predicted pathogenic missense variants were detected in DNA damage repair (DDR) genes. Three DDR genes were affected: ARID1A, MGMT, and MSH6. Among the nine predicted pathogenic mutations detected in known cancer-predisposing genes, one was a frameshift deletion and the others were missense mutations. Seven tumor suppressor genes were involved: PTCH2, ALPK2, CIC, NOTCH1, NOTCH2, TSC2, and CDKN2A. One patient with multiple pathogenic variants in two DDR genes, ARID1A and MSH6, received a schwannomatosis diagnosis at 33 years old. Each of the other patients who had single variants in the DDR gene received their diagnoses at 41 years of age. The age at diagnosis was 40 years or older in patients with variants in cancer-predisposing genes, except for one patient who had multiple variants in TSC2 and CDKN2A. The carrier of those variants received the diagnosis at 24 years old.

CONCLUSIONS

This study identified first-hit candidate mutations predisposing patients to schwannomatosis that were not related to SMARCB1 or LZTR1 variations in a cohort of patients with sporadic schwannomatosis. Patients with sporadic schwannomatosis without SMARCB1 or LZTR1 genetic variation may have developed the disease because of genomic variants related to cancer initiation in areas other than chromosome 22. Seven of 10 patients had predicted pathogenic germline mutations in DDR and cancer predisposition genes. We detected multiple cancer-related mutations in each patient. The age at the time schwannomatosis was diagnosed might be associated with a combination of variants and characteristics of the genes containing the variants; however, we did not have enough patients to confirm this association.

CLINICAL RELEVANCE

The germline mutations identified in this study and the ideas related to the age of disease onset may provide potential candidate variants for future research on sporadic schwannomatosis and help to revise the current clinical and molecular diagnostic criteria. Further in vivo and in vitro studies are needed for these variants.

Origin of Satellite Ganglion Cysts with Effusion in the Flexor Hallucis Longus Tendon Sheath around the Hallux

Background

To describe the clinical and magnetic resonance imaging findings of ganglion cysts with effusion in the flexor hallucis longus tendon sheath around the hallux to evaluate their origin.

Methods

Patients with recurrent or painful ganglion cysts around the hallux with effusion in the flexor hallucis longus tendon sheath who underwent surgical treatment at St. Vincent's Hospital from February 2007 to August 2016 were investigated. Surgical indication was a painful or recurrent mass caused by the cystic lesions. Those without effusion of the flexor hallucis longus tendon sheath were excluded. We assessed the clinical and magnetic resonance imaging findings.

Results

Magnetic resonance imaging findings in all patients showed several ganglion cysts around the hallux and large fluid accumulations within the flexor hallucis longus tendon sheath. Regarding the location, six ganglion cysts were on the dorsomedial aspect, one on the plantar medial aspect, seven on the plantar lateral aspect, and one in the toe pulp. Ten patients showed joint effusions in both the metatarsophalangeal and interphalangeal joints, two in the metatarsophalangeal joints, and three in the interphalangeal joints. There were communication stalks with a tail shape or abutment between ganglion cysts with surrounding joint effusions. Intraoperatively, connections between ganglion cysts, the synovial cyst of the flexor hallucis longus tendon sheath, and surrounding joints were seen.

Conclusions

Synovial fluid accumulation in the metatarsophalangeal or interphalangeal joint supplies the synovial cyst of the flexor hallucis longus tendon sheath and subsequently ganglion cysts in the hallux. In clinical practice, the surgeon should carefully check surrounding joints with tendon sheaths to prevent recurrence of the ganglion cysts around the hallux.

Prognostic significance of chemotherapy-induced necrosis in osteosarcoma patients receiving pasteurized autografts

Background

Among various reconstruction methods after wide excision for osteosarcoma, pasteurized autograft is often preferred. While the whole area of the tumor can be assessed for chemotherapy-induced necrosis, one of the important prognostic factors, in other reconstructive techniques, only a portion removed from a wide-resection specimen is available when using pasteurized autograft method. The assessment, therefore, may be unreliable. We analyzed the prognostic significance of the chemotherapy-induced necrosis in osteosarcoma patients who underwent reconstruction with pasteurized autografts.

Patients and methods

We reviewed the records of osteosarcoma patients who underwent treatment in our institution from 1998 to 2013. Cases of reconstruction with pasteurized autografts were defined as the patient group, and the same number of patients who underwent other reconstruction methods served as controls. Chemotherapy-induced necrosis was evaluated for removed extra-osseous and curetted intramedullary tumor tissues.

Results

A total of 22 patients were identified; the median age was 15.5 years, and there were 12 males. The most common tumor location was the distal femur. The most common histological subtype was osteoblastic. Median size was 8.1 cm. Disease status was stage IIB in 13 patients and IIA in 9. Median follow-up was 76 months. No differences between the patient and control groups were observed in potential prognostic factors, overall survival, metastasis-free survival, or recurrence-free survival. Univariate analyses demonstrated that histological response was a significant prognostic factor for metastasis-free survival and also significant for recurrence-free survival.

Conclusion

Chemotherapy-induced necrosis grading, using only available tumor tissues, could be a prognostic factor for osteosarcoma patients receiving pasteurized autografts for reconstructive surgery.

The Effect of Autologous Platelet-Rich Plasma on Bone Regeneration by Autologous Mesenchymal Stem Cells Loaded onto Allogeneic Cancellous Bone Granules

To develop a clinically effective bone regeneration strategy, we compared bone regeneration using allogeneic cancellous bone granule scaffolds loaded with autologous bone marrow-derived mesenchymal stem cells (BM-MSC) with or without autologous platelet-rich plasma (PRP). Critical-sized segmental bone defects were made at the mid-shaft of both radiuses in 41 New Zealand White rabbits. Small-sized allogeneic cancellous bone granules (300-700 μm in diameter) loaded with BM-MSC were implanted on one side, and PRP was added. On the other side, autologous BM-MSC loaded onto allogeneic cancellous granules were grafted as a control. Bone regeneration was assessed by radiographic evaluation at 4, 8, and 16 weeks postimplantation and by micro-computed tomography (micro-CT) and histological evaluation of the retrieved specimens at 8 and 16 weeks. The experimental group did not show significantly higher bone quantity indices than the control group at any time point. Micro-CT analysis revealed that both groups had similar mean total volumes, surface areas, and other parameters at 8 and 16 weeks. Histological evaluation of 8- and 16-week specimens also showed a similar progression of new bone formation and maturation. In this experiment using a contralateral control group in the same individual, an initial single addition of PRP in allogeneic cancellous bone granules loaded with BM-MSC for critical-sized bone defects in the weight-bearing area did not induce a consequent difference in bone healing. Further research into the optimal preparation and application of PRP is necessary. Furthermore, studies involving a greater number of subjects and larger experimental animals could determine the clinical relevance of PRP treatment.

Pseudomyxoma peritonei extending to the lower extremity: a case report

Pseudomyxoma peritonei is characterized by mucinous ascites originating from a mucin-producing neoplasm; however, even the definition is still under debate. Tumor deposits extend and ultimately engulf the entire cavity, causing death from cachexia due to limited intestinal movement. Here, we report a unique case of an 80-year-old woman with pseudomyxoma peritonei, which extended to the lower extremity mimicking infectious condition. The patient survived for a long time without bowel obstruction despite having the histologic subtype that has an unfavorable prognosis. The extremity lesion was treated with limited extensive surgery. The origin of the disease and the mechanism of extension to the extremity could not be clarified. Clinicians should be aware of the original disease entity and this unusual presentation and determine its mechanism and the best management strategy.

Osteosarcoma in Asian Populations Over the Age of 40 Years: A Multicenter Study

BACKGROUND

Elderly patients with osteosarcoma (OSA) are no longer uncommon; however, many questions remain regarding this population. We investigated the clinicopathological characteristics and prognostic factors of OSA in an Asian population over the age of 40 years.

METHODS

This was a multi-national, multi-institutional study by the Eastern Asian Musculoskeletal Oncology Group (EAMOG).

RESULTS

A total of 232 patients were enrolled (116 males and 116 females), with a median age of 50 years at diagnosis; 25 (10.8 %) patients exhibited initial metastasis. Median follow-up was 52 months for survivors. We observed 102 osteolytic and mixed radiographic findings for 173 lesions. Histological subtypes other than osteoblastic type were frequent. Radiation-associated OSA was seen in seven patients, with a 5-year overall survival (OS) of 16.7 %. No Paget's OSA was observed. High-grade spinopelvic OSA was seen in 29 (12.5 %) patients. The 5-year OS was 59.4 % in patients without initial metastasis and 45.2 % in patients with spinopelvic OSA. While surgery and initial metastasis were common prognostic factors for OS, chemotherapy was not. Histologic response to neoadjuvant chemotherapy was poor in 61 of 83 patients.

CONCLUSION

This study revealed distinct clinicopathological features of OSA patients over 40 years of age compared with younger patients, such as the high incidence of axial tumors, common osteolytic and mixed radiographic findings, the high frequency of unusual histologic subtypes, and poor prognosis. Contrary to Western elderly patients with OSA, there was no Paget's OSA in this study, which may result in a lower incidence of secondary OSA. Prognostic factor analyses demonstrated chemotherapy did not influence OS.