Localized Myxofibrosarcoma: A Retrospective Analysis of Primary Therapy and Prognostic Factors in 134 Patients in a Single Institution.

BACKGROUND: Primary therapy of localized myxofibrosarcoma (MFS) remains controversial. Primary resection is complicated by a high rate of local recurrence, and the refractoriness to non-surgical treatment results in a higher risk of metastasis. The aim of the present study was to contribute the findings of a single sarcoma-specialized center and encourage investigating new treatment options. PATIENTS AND METHODS: We analyzed 134 patients treated with localized MFS in our center regarding prognostic factors defining overall survival, local recurrence, and metastasis. We focused on multimodal treatment of localized MFS: surgery, radiation, chemotherapy, hyperthermia, and isolated limb perfusion. RESULTS: The 5-year OS was 74.9%. From a total of 134 patients: 74 (55.2%) stayed disease free, 48 (35.8%) had a local recurrence (LR), and 23 (17.2%) developed a distant metastasis (DM). The 5-year LR-free survival (LRFS) and DM-free survival (DMFS) were 66.1% and 80.8%, respectively. Older age, tumor size (cT) cT ≥ 2, non-extremity localization, and distant metastasis were adverse predictive factors for OS. Performing an incision biopsy, surgery in a sarcoma-center, wide local excision or compartment-oriented excision, negative margins, and radiotherapy were positive predictive factors for LR. Tumor size cT ≥ 3 was a negative predictive factor for DM. Grading was a negative predictive factor for LR (G ≥ 2) and for DM (G3) in the multivariable analysis. CONCLUSION: Adjuvant radiation had a positive impact on LRFS in all localized tumor stages, even in cT1 tumors. Chemotherapy did not have a significant impact on DMFS, regardless of tumor stage. Our findings indicate that myxofibrosarcoma may be a chemotherapy-resistant entity and a much closer monitoring is required, in case of neoadjuvant treatment.

H3F3A-mutated giant cell tumour of bone without giant cells-clinical presentation, radiology and histology of three cases.

AIMS: Giant cell tumour of bone (GCTB) is histologically defined as a lesion containing reactive giant cells and a neoplastic mononuclear cell population; in up to 92% of cases, GCTB is characterised by a specific mutation of the histone gene H3F3A. The cellular composition ranges from giant-cell-rich to giant-cell-poor. The diagnosis of GCTB can be challenging, and several other lesions need to be excluded, e.g. aneurysmal bone cysts, non-ossifying fibromas, chondroblastomas, brown tumours, and giant-cell-rich osteosarcomas. Our aim was to analyse the clinical history, imaging, molecular pathology and histology of three H3F3A-mutated bone tumours without detectable giant cells. None of the patients received denosumab therapy. METHODS AND RESULTS: Diagnostic material was obtained by curettage or resection and/or biopsy. Common histomorphological features of all three reported lesions were fibrocytic, oval cells in a background of osteoid and an absence of multinuclear giant cells as confirmed with CD68 immunohistochemistry. We used immunohistochemistry and Sanger sequencing to demonstrate positivity for the H3.3 p.G34W mutation. Differential diagnoses were systematically excluded on the basis of histomorphology, immunohistochemistry, and fluorescence in-situ hybridisation. The imaging (radiography, computed tomography, and magnetic resonance imaging) for all three cases is presented and discussed. CONCLUSIONS: We believe that these GCTBs without giant cells expand one end of the heterogeneous range of GCTB. Because of the lack of giant cells, correct diagnosis of GCTB is challenging or even impossible on histological grounds alone. In these cases, detection of the characteristic H3F3A mutation (G34W-specific antibody RM263 or sequencing) is extremely helpful for diagnosing those lesions without giant cells as giant cell tumours of bone.

Osteoporosis Caused by Systemic Mastocytosis: Prevalence in a Cohort of 8392 Patients with Osteoporosis.

Indolent systemic mastocytosis (ISM) is a group of heterogenous diseases characterized by abnormal accumulation of mast cells in at least one organ. ISM can be a cause of osteoporosis. The aim of this study is to determine the prevalence, and the prognosis of ISM in a cohort of patients with osteoporosis. In this monocentric and retrospective study, patients with osteoporosis who did not receive a bone biopsy (cohort 1) and patients that subsequently received a diagnostic bone biopsy for differential diagnosis (cohort 2) are compared with patients who are diagnosed with ISM (cohort 3). A total of 8392 patients are diagnosed with osteoporosis. Out of these patients 1374 underwent a diagnostic bone biopsy resulting in 43 patients with ISM. These figures indicate that ISM is diagnosed in 0.5% of patients with osteoporosis and in 3.1% (men 5.8%) of patients who underwent bone biopsies. Patients with ISM sustained significantly more vertebral fractures in comparison to patients in cohort 2 (4.4 ± 3.6 versus 2.4 ± 2.5 vertebral fractures, p < 0.001) and women were significantly younger compared to cohort 2 (57.3 ± 12 versus 63.6 ± 12 years, p < 0.05). Only 33% showed an involvement of the skin (urticaria pigmentosa). ISM is a rare cause of osteoporosis (0.5%). However, in a subgroup of rather young male patients with osteoporosis the prevalence is more than 5%. Thus, ISM should be considered in premenopausal women and men presenting with vertebral fractures even if urticaria pigmentosa is not present.

Molecular Analysis of Hybrid Neurofibroma/Schwannoma Identifies Common Monosomy 22 and α-T-Catenin/CTNNA3 as a Novel Candidate Tumor Suppressor.

Neurofibromas and schwannomas are benign Schwann cell-derived peripheral nerve sheath tumors arising sporadically and within neurofibromatoses. Multiple tumors are a hallmark of neurofibromatosis type 1 (NF1) and type 2 (NF2) and schwannomatosis. Neurofibromas in NF1 and schwannomas in NF2 or schwannomatosis are defined by distinctive molecular hits. Among these, multiple hybrid neurofibromas/schwannomas may also appear, not yet being defined by a molecular background. We therefore performed molecular analysis of 22 hybrid neurofibromas/schwannomas using array comparative genomic hybridization, immunohistochemistry, quantitative RT-PCR, and functional analyses of cultured Schwann cells. Furthermore, we analyzed SMARCB1 by fluorescence in situ hybridization and multiplex ligation-dependent probe. Monosomy 22 was identified in 44% of tumors of tested patients with hybrid neurofibromas/schwannomas. In addition, in a single case, we detected focal deletion of the α-T-catenin/CTNNA3 gene (10q21.3). To further characterize this candidate, transient knockdown of α-T-catenin in Schwann cells was performed. CTNNA3 depleted cells showed cytoskeletal abnormalities and reduced E-cadherin expression, indicating epithelial-mesenchymal transition-like abnormalities. To conclude, we uncovered loss of chromosome 22 in almost half of all cases with hybrid neurofibromas/schwannomas of patients with multiple peripheral nerve sheath tumors. We tagged α-T-catenin/CTNNA3 as a novel candidate gene. Our functional investigations might indicate involvement of α-T-catenin/CTNNA3 in the biology of peripheral nerve sheath tumors.

Metastatic Potential of Grade I Chondrosarcoma of Bone: Results of a Multi-institutional Study.

BACKGROUND: Little is known about the metastatic potential of low-grade chondrosarcoma. This study was designed to evaluate the rate of metastasis to identify possible risk factors. METHODS: The files of 225 patients with newly diagnosed, grade I chondrosarcoma of bone treated between 1975 and 2012 were retrospectively analyzed. Median follow-up was 80 months for survivors (range 24-445 months). Nonparametric analyses were performed with the Mann-Whitney U test. Survival curves were calculated with the Kaplan-Meier method and compared with the log-rank test. RESULTS: Fourteen patients developed metastases after a median of 49 months. Metastasis-free survival probability (MFS) was 95 % at 5 years and 92 % at 10 years. Post-metastasis survival probability amounted to 27 % after 5 years. Tumor size at diagnosis (P = 0.698) and surgical margin width (P = 0.514) had no influence on MFS. Patients who developed local recurrences had a significantly lower 10-year MFS than patients without recurrences (69 % vs. 99 %, P < 0.001). Patients with grade I recurrences had a significantly poorer MFS than patients without recurrences (P = 0.013) but a significantly higher MFS than patients with grade II recurrences (P = 0.006). Patients with thoracic wall tumors had a significantly lower 10-year MFS of 66 % compared with patients with tumors of the upper (100 %, P < 0.001) and lower extremity (93 %, P = 0.033). CONCLUSIONS: The biological behavior of low-grade chondrosarcoma appears to be more consistent with the WHO definition of rarely metastasizing bone tumors, rather than the one of locally aggressive neoplasms. Thoracic wall tumors and the development of local recurrences were associated with a higher metastasis rate in this study.

Histological response assessment following neoadjuvant isolated limb perfusion in patients with primary, localised, high-grade soft tissue sarcoma.

PURPOSE: Histological response assessment following neoadjuvant treatment can help identify patients at a higher risk for systemic disease progression. Our goal was to evaluate whether mitotic count and the amount of viable tumour following neoadjuvant isolated limb perfusion (ILP) for primary, locally advanced, non-metastatic, high-grade extremity soft tissue sarcoma correlate with prognosis. PATIENTS AND METHODS: This study is a retrospective analysis of 61 patients who underwent neoadjuvant ILP followed by surgical resection with curative intent between 2001 and 2011. Non-parametric analyses were carried out with the Mann-Whitney U and the Wilcoxon signed-rank test. Survival curves were calculated with the Kaplan-Meier method and compared with the log-rank test. RESULTS: The median follow-up was 44 months for all patients and 55 months for survivors. The amount of viable tumour after ILP had no correlation with overall (OS) (P = 0.227) or event-free (EFS) (P = 0.238) survival probability. Patients with a low mitotic count after ILP had a significantly higher OS (P < 0.001), EFS (P = 0.002) and post-relapse survival probability (P = 0.030) compared to patients with an intermediate or high mitotic count. CONCLUSIONS: The mitotic count following ILP for primary, high-grade, locally advanced, non-metastatic soft tissue sarcoma appears to significantly correlate with prognosis. If these results are validated in a prospective setting, they could provide a rationale for the design of adjuvant systemic chemotherapy trials with the goal of improving the prognosis of patients with an intermediate or high mitotic count after ILP.

Is vitamin D insufficiency or deficiency related to the development of osteochondritis dissecans?

PURPOSE: The aetiology of osteochondritis dissecans is still unclear. The aim of this prospective pilot study was to analyse whether vitamin D insufficiency, or deficiency, might be a contributing etiological factor in the development of an OCD lesion. METHODS: The serum level of vitamin D3 in 23 consecutive patients (12 male and 11 female) suffering from a stage III, or stages III and IV, OCD lesion (mostly stage III) admitted for surgery was measured. RESULTS: The patients' mean age was 31.3 years and most of them already exhibited closed epiphyseal plates. In the majority of patients (18/23), a distinct vitamin D3 deficiency was found, two patients were vitamin D3-insufficient and, in three patients, the vitamin D3 level reached the lowest normal value. CONCLUSION: These first data show that a vitamin D3 deficiency rather than an insufficiency may be involved in the development of OCD lesions. Probably, with a vitamin D3 substitution, the development of an advanced OCD stage could be avoided. Further analyses, including morphological analyses regarding a possible osteomalacia, and examination of the PTH and other determinants of the bone metabolism, should be undertaken to either confirm or refute these data. LEVEL OF EVIDENCE: IV.

Osteosarcoma in patients with Rothmund-Thomson syndrome.

BACKGROUND: Rothmund-Thomson syndrome (RTS) is associated with an increased risk of osteosarcoma, but information about affected patients is limited. PROCEDURE: Seven patients with osteosarcoma, treated in the Cooperative Osteosarcoma Study Group-trials, had a diagnosis of RTS. Their patient-, tumor- and treatment-related variables and outcome were reviewed retrospectively. RESULTS: Median age at diagnosis of osteosarcoma was 13 years (range 7-16), five were female, two male. Tumor involved proximal tibia (n = 4), distal tibia (n = 1), distal fibula (n = 1) and proximal ulna (n = 1). Three patients had metastatic disease at diagnosis. All patients received surgery and chemotherapy. Four of seven patients required dose modifications and three of them terminated treatment prematurely. Complete resection of the primary tumor was achieved in all individuals. Two of three affected patients failed to achieve surgical clearance of their primary metastases and died. The third patient relapsed with multiple metastases and died. Two of four patients with localized disease were alive in first complete remission, a third patient in second complete remission after recurrence and a fourth patient died of acute leukemia, while still in first complete remission of osteosarcoma. CONCLUSIONS: Patients with RTS and osteosarcoma may be cured of their cancer with appropriate multimodal therapy. They should be treated like other osteosarcoma patients but preexisting disorders, needs for special support and development of toxicities have to be considered.

Prognostic relevance of ¹8F-FDG PET uptake in patients with locally advanced, extremity soft tissue sarcomas undergoing neoadjuvant isolated limb perfusion with TNF-α and melphalan.

PURPOSE: The objective of this study was to determine whether (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) can adequately assess the risk of systemic disease progression in patients with primary, localized, high-grade soft tissue sarcomas of the extremities undergoing neoadjuvant isolated limb perfusion (ILP) with tumour necrosis factor and melphalan. METHODS: This was a retrospective analysis of the files of 35 patients who underwent a PET or PET/CT scan prior to and after ILP followed by surgical resection with curative intent between 2006 and 2012. SUVmax1 was defined as the maximum standardized uptake value (SUV) at diagnosis, SUVmax2 as the maximum SUV after ILP and ΔSUVmax as the percentage difference between SUVmax1 and SUVmax2. RESULTS: The median follow-up was 40 months for all patients. The median SUVmax1 amounted to 7.6, while the median SUVmax2 was 4.7. The median ΔSUVmax was -44%. Overall survival (OS) probability at 2 and 5 years amounted to 78 and 70%, respectively, while metastasis-free survival (MFS) probability at 2 and 5 years was 67 and 64%, respectively. Receiver-operating characteristic (ROC) curve analysis showed that both SUVmax2 and ΔSUVmax could predict systemic disease progression, while SUVmax1 could not adequately identify patients who went on to develop metastatic disease. The optimal cut-off value was 6.9 for SUVmax2 and -31 % for ΔSUVmax. Patients with an SUVmax2 <6.9 had a 2-year MFS of 80%, compared to 31 % for patients with an SUVmax2 ≥ 6.9 (p < 0.001). Patients with a ΔSUVmax < -31 %, i.e. patients with a higher metabolic response, had an MFS of 76% at 2 years, compared to 42% for patients with a ΔSUVmax ≥ -31% (p = 0.050). CONCLUSION: SUVmax after ILP for primary, locally advanced, non-metastatic high-grade soft tissue sarcomas of the extremities appears to be significantly correlated with prognosis. Whether patients with a high SUVmax after ILP will benefit from standard or experimental adjuvant systemic treatment options should be evaluated in future studies.

Congenital osteofibrous dysplasia Campanacci: spontaneous postbioptic regression.

Osteofibrous dysplasia Campanacci is a rare benign bone tumor most frequently observed in young childhood. The exclusive localization in the tibia is very characteristic. The incidence of congenital primary bone tumors is an absolute rarity. We report a case of a newborn with a histologically proven osteofibrous dysplasia Campanacci at the tibia presenting a regular radiographic follow-up. After a small open biopsy and spontaneous minor fracture, the lesion rapidly remodeled within 1½ months and almost completely regressed with restutio ad integrum. Surgical intervention in this tumor entity at childhood age has been shown to have a high recurrence rate but due to lack of experience with newborns, guidelines do not exist. We analyze the radiologic and histologic differential diagnosis of juvenile adamantinoma and emphasize that congenital peripheral bone tumors should be treated conservatively when malignancy is excluded.

Intraosseous myolipoma of the calcaneus.

A man in his 40s presented with an incidental finding of an osteolytic bone lesion. He sustained an ankle injury while inline skating, fracturing his lateral malleolus. Besides the fracture, radiographic imaging on the day of the injury incidentally revealed a well-defined solitary osteolytic lesion with a sclerotic rim within the right calcaneus. MRI showed an intraosseous, fat-containing lesion with focal contrast enhancement, assessed as an intraosseous lipoma with central necrosis. In the pathological analysis of a sample of the lesion an intraosseous myolipoma of the calcaneus was found-an unexpected and extraordinary finding. To prevent pathological fracturing, curettage and bone grafting were performed using autologous iliac crest bone in combination with allogenous bone chips.

Primary Multi-Systemic Metastases in Osteosarcoma: Presentation, Treatment, and Survival of 83 Patients of the Cooperative Osteosarcoma Study Group.

BACKGROUND: To evaluate patient and tumour characteristics, treatment, and their impact on survival in patients with multi-systemic metastases at initial diagnosis of high-grade osteosarcoma. Precedure: Eighty-three consecutive patients who presented with multi-systemic metastases at initial diagnosis of high-grade osteosarcoma were retrospectively reviewed. In cases of curative intent, the Cooperative Osteosarcoma Study Group recommended surgical removal of all detectable metastases in addition to complete resection of the primary tumour and chemotherapy. RESULTS: Eighty-three eligible patients (1.8%) were identified among a total of 4605 individuals with high-grade osteosarcoma. Nine (10.8%) of these achieved complete surgical remission, of whom seven later had recurrences. The median follow-up time was 12 (range, 1-165) months for all patients. Actuarial event-free survival after 1, 2, and 5 years was 9.6 ± 3.2%, 1.4 ± 1.4%, and 1.4 ± 1.4%, and overall survival was 54.0 ± 5.6%, 23.2 ± 4.9%, and 8.7 ± 3.3%. In univariate analyses, elevated alkaline phosphatase before chemotherapy, pleural effusion, distant bones as metastatic sites, and more than one bone metastasis were negative prognostic factors. Among treatment-related factors, the microscopically complete resection of the primary tumour, a good response to first-line chemotherapy, the macroscopically complete resection of all affected tumour sites, and local treatment (surgery ± radiotherapy) of all bone metastases were associated with better outcomes. Tumour progression under first-line treatment significantly correlated with shorter survival times. CONCLUSION: The outlook for patients with multi-systemic primary metastases from osteosarcoma remains very poor. The utmost importance of surgical resection of all tumour sites was confirmed. For unresectable bone metastases, radiotherapy might be considered. In the patient group studied, standard chemotherapy was often insufficiently effective. In the case of such advanced disease, alternative treatment options are urgently required.

Solitary skeletal osteosarcoma recurrence. Findings from the Cooperative Osteosarcoma Study Group.

BACKGROUND: Solitary skeletal osteosarcoma (OS) manifestations distant from the site of the primary tumor rarely arise as only sign of disease recurrence. METHODS: This report reviews 38 patients with high-grade central OS of the limbs or axial skeleton and initial complete surgical remission (CR) who developed first recurrences as solitary osseous lesions distant from the primary tumor. The Cooperative Osteosarcoma Study Group (COSS) database was used to evaluate patient-, tumor-, and treatment-related variables and outcomes. RESULTS: Thirty-eight patients (27 males and 11 females; 36 limb and 2 axial primaries) developed solitary osseous recurrences a median of 2.1 years (range: 0.5-14.3) from primary diagnosis. Relapses involved axial (24), extremity (10), or craniofacial bones (4). Treatment for recurrence included surgery (28), radiotherapy (10), and chemotherapy (27). After a median follow-up of 1.9 years (range: 0.1-21.2) from first recurrence for all 38 patients and 5.5 years (0.3-21.2) for 16 survivors (10 in continuous second CR), 2- and 5-year overall and event-free survival (EFS) probabilities were 55% and 34% and 34% and 27%, respectively. A long interval to recurrence (>1.5 years) predicted for better overall (P < 0.001) and EFS (P = 0.005). For 21 patients achieving a second CR, 2- and 5-year overall and EFS probabilities were 81% and 61% and 52% and 49%, respectively, while only 1/17 others survived beyond 5 years (P < 0.001). Survivors (14/16) had also received second-line chemotherapy. CONCLUSION: First solitary skeletal recurrences of OS should be treated with curative intent. Some presumed bone metastases may represent second primary OSs.

Survival and prognostic factors in chondrosarcoma: results in 115 patients with long-term follow-up.

BACKGROUND AND PURPOSE: There have been few long-term studies on the outcome of chondrosarcoma and the findings regarding prognostic factors are controversial. We examined a homogeneous group of patients with primary central chondrosarcoma of bone who were treated according to a uniform surgical protocol at our institution, in order to determine the factors that influence survival and identify potential improvements to our therapeutic algorithm. PATIENTS AND METHODS: We performed a retrospective analysis of 115 patients with primary central chondrosarcoma of bone who presented with localized disease and who had a minimum follow-up of 5 years after diagnosis. 68 tumors were localized in the extremities and 47 in the axial skeleton or pelvis. 59 patients had a high-grade (II and III) and 56 a low-grade (I) tumor. 94 patients underwent surgical resection with adequate (wide or radical) margins, while 21 patients had inadequate (marginal or intralesional) margins. RESULTS: Tumor grade and localization were found to be statistically significant independent predictors of disease-related deaths in multivariate analysis. The quality of surgical margins did not influence survival. The AJCC staging system was able to predict prognosis in patients with chondrosarcoma of the extremities, but not in those with tumors of the axial skeleton and pelvis. Long-term survival after secondary metastatic disease was only observed when metastases were resected with wide margins. Patients with metastases who received further treatment with conventional chemotherapy, radiotherapy, and/or further surgery had significantly better survival compared to those who received best supportive care. INTERPRETATION: The outcome in patients with primary central chondrosarcoma of bone who present with localized disease is mostly affected by tumor-related parameters.

Osteochondral Lesions of the Talus: A Review on Talus Osteochondral Injuries, Including Osteochondritis Dissecans.

This is a review on talus osteochondritis dissecans and talus osteochondral lesions. A majority of the osteochondral lesions are associated with trauma while the cause of pure osteochondritis dissecans is still much discussed with a possible cause being repetitive microtraumas associated with vascular disturbances causing subchondral bone necrosis and disability. Symptomatic nondisplaced osteochondral lesions can often be treated conservatively in children and adolescents while such treatment is less successful in adults. Surgical treatment is indicated when there is an unstable cartilage fragment. There are a large number of different operative technique options with no number one technique to be recommended. Most techniques have been presented in level II to IV studies with a low number of patients with short follow ups and few randomized comparisons exist. The actual situation in treating osteochondral lesions in the ankle is presented and discussed.

Osteochondritis Dissecans of Smaller Joints: The Elbow.

This review presents the current understanding of the etiology, pathogenesis, and how to diagnose and treat osteochondritis dissecans (OCD) at the elbow joint followed by an analysis of particular characteristics and outcomes of the treatment. OCD is seen in patients with open growth plates (juvenile OCD [JOCD] and in adults [AOCD] with closed growth plates [adult OCD). The etiology at smaller joints remains as unclear as for the knee. Mechanical factors (throwing activities [capitulum] seem to play an important role. Clinical symptoms are unspecific. Thus, imaging techniques are most important for the diagnosis. In low-grade and stable lesions, treatment involves rest and different degrees of immobilization until healing. When surgery is necessary, the procedure depends on the OCD stage and on the state of the cartilage. With intact cartilage, retrograde procedures are favorable while with damaged cartilage, several techniques are used. Techniques such as drilling and microfracturing produce a reparative cartilage while other techniques reconstruct the defect with osteochondral grafts or cell-based procedures such as chondrocyte implantation. There is a tendency toward better results when reconstructive procedures for both the bone and cartilage are used. In addition, comorbidities at the joint have to be treated. Severe grades of osteoarthritis are rare.

Incorporation of an Allogenic Cortical Bone Graft Following Arthrodesis of the First Metatarsophalangeal Joint in a Patient with Hallux Rigidus.

Hallux rigidus is degenerative arthritis of the first metatarsophalangeal joint characterized by pain and stiffness in the joint with limitation of motion and functional impairment. Recently, bone grafts have been introduced in orthopedic procedures, namely osteosynthesis and arthrodesis. Allografts can induce bone formation, provide support for vascular and bone ingrowth and have a low risk of immunological rejection. A 52-year-old female patient with hallux rigidus underwent arthrodesis of the first metatarsophalangeal joint using Shark Screw® made of allogenic cortical bone. Corrective surgery was performed after 10 weeks, and a 5 × 3 mm large part of the Shark Screw® with the surrounding patient's bone was removed. A histological evaluation revealed a vascularized graft with the newly formed compact lamellar bone fitting exactly to the cortical graft. The bone surface was lined by plump osteoblasts with osteoid production, and osteocytes were present in the lacunae. The arthrodesis of the first metatarsophalangeal joint using an allogenic cortical bone graft results in fast, primary bone healing without immunological rejection. This case suggests that the cortical allograft is a good and safe treatment option with an excellent graft incorporation into the host bone. However, as the literature evaluating the histology of different bone grafts is scarce, further high-level evidence studies with adequate sample sizes are needed to confirm our findings.

Elevated Bone Hardness Under Denosumab Treatment, With Persisting Lower Osteocyte Viability During Discontinuation.

Denosumab is a potent osteoclast inhibitor targeted to prevent osteoporotic bone loss and thereby reduce fractures in the aging population. Recently, an elevated risk of rebound fractures following denosumab discontinuation was identified, unless patients were transitioned to an alternative antiresorptive medication. How denosumab affects the interaction of mechanosensitive osteocytes and bone quality remains unknown. We hypothesized that denosumab influences osteocyte function contributing to bone reorganization and increased fractures during discontinuation. Bone quality and osteocytes were assessed in archived iliac crest bone biopsies obtained from patients with high fracture occurrence from 2011 to 2016. Biopsies were obtained due to high fracture occurrence prior and during osteoporosis therapy from (i) patients with at least two semiannual subcutaneous injections of 60 mg denosumab, (ii) patients with rebound fractures during discontinuation, and (iii) patients of a treatment-naive group. In total, biopsies from 43 individuals were analyzed (mean age, 65.5 ± 12.1 years). Our results showed that during denosumab treatment, iliac cortical bone had a higher bone tissue hardness compared to treatment-naive bone (p = 0.0077) and a higher percentage of mineralized osteocyte lacunae (p = 0.0095). The density of empty osteocyte lacunae was higher with denosumab compared to treatment-naive (p = 0.014) and remained high in trabecular bone during discontinuation (p = 0.0071). We conclude that during denosumab treatment, increased bone hardness may contribute to improved fracture resistance. In biopsies from patients with high fracture occurrence, denosumab treatment reduced osteocyte viability, an effect that persisted during treatment discontinuation. High-resolution imaging of osteocyte viability indicates a role for osteocytes as a potential future mechanistic target to understand rebound bone loss and increased fractures with denosumab discontinuation.

Pathological Fracture and Prognosis of High-Grade Osteosarcoma of the Extremities: An Analysis of 2,847 Consecutive Cooperative Osteosarcoma Study Group (COSS) Patients.

PURPOSE: The objective of this study was to investigate potential correlations between pathologic fractures (PFs) and prognosis of patients with primary central high-grade osteosarcoma of the extremities. METHODS: We retrospectively analyzed 2,847 patients registered in the Consecutive Cooperative Osteosarcoma Study Group database with primary central high-grade osteosarcoma of the extremities, treated between 1980 and 2010. Intended treatment included pre- and postoperative chemotherapy and surgery. Univariable and multivariable survival analyses were performed for all patients and then differentiated for adult and pediatric (≤ 18 years at time of diagnosis) patients. RESULTS: A total of 2,193 patients were ≤ 18 years of age; 11.3% of all patients had PFs. In the overall cohort, presence of PF correlated significantly with tumor site, histologic subtype, relative tumor size, and primary metastases, but not with body mass index or local surgical remission. In univariable analysis, 5-year overall survival (OAS) of patients with and without PF was 63% versus 71%, respectively (P = .007), and 5-year event-free survival (EFS) was 51% versus 58% (P = .026). In pediatric patients, OAS and EFS did not differ significantly between patients with and without PF. In adults, 5-year OAS in patients with and without PF was 46% versus 69% (P < .001), and 5-year EFS was 36% versus 56% (P < .001). In multivariable analysis, PF was not a statistically significant factor for OAS or EFS in the total cohort or in pediatric patients. In adult patients, PF remained an independent prognostic factor for OAS (P = .013; hazard ratio [HR], 1.893). It was not a significant prognostic factor for EFS (P = .263; HR, 1.312). CONCLUSION: In this largest study to date with extremity osteosarcomas, we observed the occurrence of PF to correlate with inferior OAS expectancies in adult but not in pediatric patients.