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Osteosarcoma is the most frequent primary malignant bone tumor among the children. The advent of neoadjuvant chemotherapy significantly improved the prognosis of patients with osteosarcoma in the 1980s, but it has since plateaued in the past decades. Recently, one of the most researched areas in sarcoma treatment is tyrosine kinases. Here, we describe research on a serine/threonine kinase, cyclin G–associated kinase (GAK), which has not been reported in osteosarcoma previously. In this study, a lentiviral based human shRNA library was utilized to screen for kinases in KHOS and U-2OS osteosarcoma cells. The expression of GAK was examined in osteosarcoma and the effect on cell proliferation was analyzed by GAK siRNA knockdown. The level of GAK expression and its correlation to prognosis was analyzed in osteosarcoma tissue microarray. The effect of GAK depletion on insulin-like growth factor and epidermal growth factor receptor–mediated signal transduction was analyzed by Western blot. We observed that GAK was overexpressed in both osteosarcoma cell lines and tissue samples when compared with human osteoblasts. GAK knockdown by siRNA decreased cell proliferation in both drug-sensitive and multidrug-resistant osteosarcoma cell lines. Immunohistochemistry of osteosarcoma tissue microarray revealed that overexpression of GAK was associated with poor prognosis. Finally, knockdown of GAK resulted in alterations of receptor trafficking and several downstream proteins. In conclusion, our results suggest that osteosarcoma cell proliferation and survival are dependent on GAK. These findings may lead to the development of new therapeutic options for osteosarcoma. Mol Cancer Ther; 9(12); 3342–50. ©2010 AACR.

Supplementary Figure 1 from Cyclin G–Associated Kinase Is Necessary for Osteosarcoma Cell Proliferation and Receptor Trafficking

Purpose: To explore potential therapeutic strategies for interrupting the interleukin-6 (IL-6) signaling pathway, we measured IL-6 expression in ovarian cancer tissues, and evaluated the effects of a monoclonal anti-IL-6 antibody; siltuximab (CNTO 328), on levels of IL-6–induced Stat3 phosphorylation, Stat3 nuclear translocation, and Stat3 downstream antiapoptotic genes. We then looked for enhancing paclitaxel sensitivity in multidrug-resistant ovarian cancer cell lines.Experimental Design: Expressions of IL-6 in ovarian cancer patient specimens were assessed by immunohistochemistry. Effects of siltuximab on IL-6–induced activation of Stat3 in an ovarian cancer cell line were determined by Western blot and real-time analysis of Stat3 nucleocytoplasmic translocation. Influence of combination of siltuximab and paclitaxel on tumor growth was evaluated in a xenograft mouse mode in vivo.Results: Metastatic and drug-resistant recurrent tumors have significantly higher IL-6 expression when compared with the matched primary tumors. Siltuximab specifically suppressed IL-6–induced Stat3 phosphorylation and Stat3 nuclear translocation. Treatment with siltuximab significantly decreased the levels of Stat3 downstream proteins such as MCL-1, Bcl-XL, and survivin. Treatment with siltuximab reduced expression of multiple IL-6–induced genes in these cell lines. Furthermore, siltuximab increased the cytotoxic effects of paclitaxel in a paclitaxel resistant ovarian cancer cell line in vitro, but combination therapy with siltuximab did not have a significant effect on paclitaxel resistant tumor growth in vivo.Conclusions: These results show that siltuximab effectively block the IL-6 signaling pathways and IL-6–induced gene expression. Blockage of IL-6 signaling may provide benefits for the treatment of ovarian cancer. Clin Cancer Res; 16(23); 5759–69. ©2010 AACR.

Supplementary Figures S1-S2 and Supplementary Tables S1-S3.

Due to the wide variations in location, size, local invasiveness, and treatment options, the complications associated with surgery for giant cell tumor of bone have been sporadically reported. For quality assessment, fundamental data based on large-scale surveys of complications under a universal evaluation system is needed. The Dindo-Clavien classification is an evaluation system for complications based on severity and required intervention type and is suitable for the evaluation of surgery in a heterogeneous cohort.A multi-institutional retrospective survey of 141 patients who underwent surgery for giant cell tumor of bone in the extremity was performed. The incidence and risk factors of complications, type of intervention for complication control, and impact of complications on functional and oncological outcomes were analyzed using the Dindo-Clavien classification.Forty-six cases (32.6%) had one or more complications. Of them, 18 (12.8%), 11 (7.8%), and 17 (12.1%) cases were classified as Dindo-Clavien classification grade I, II, and III complications, respectively. There were no cases with grade IV or V complications. Progression in Campanacci grading (p = 0.04), resection (over curettage, p 0.0001), reconstruction with prosthesis (p = 0.0007), and prolonged operative duration (p = 0.0002) were significant risk factors for complications. Complications had a significant impact on function (p 0.0001). Differences in the impact of complication types and tumor location on function were confirmed. Complications had no impact on local recurrence and metastasis development.The Dindo-Clavien classification could provide fundamental information, under a uniform definition and classification system, on postoperative complications in patients with giant cell tumor of bone in terms of incidence, type of intervention for complication control, risk factors, and impact on functional outcome. The data are useful not only for preoperative evaluation for the risk of complications under specific conditions but also for quality assessment of surgery for giant cell tumor of bone.

Prostate cancer often forms osteoblastic lesions that appear as a high-dense shadow upon X-ray. Although the lesions may seem to increase bone strength, pathological fracture occurs in one in four patients with prostate cancer. The aim of this study is to elucidate the factors that may increase the risk of pathological fracture in patients with prostate cancer metastases in the proximal femur by analyzing computed tomography data.Computed tomography data of the femur of 62 prostate cancer patients were retrospectively analyzed. The patients were divided into three groups based on the presence or absence of femoral metastatic lesions and pathological fracture. Surgical specimens of the proximal femur collected from patients who had a pathological fracture were histologically analyzed.Bone density in the marrow area was increased in all cases with metastases compared with those with no metastases. Contrarily, the cortical bone density at the medial trochanter region was significantly lower in patients who had pathological fractures in the proximal femur than those who did not. Accordingly, histological analysis of the surgical specimens revealed that the affected cortical bone was osteopenic without any apparent new bone formation.These results indicate that prostate cancer is less effective in inducing bone formation in the cortex than in the marrow and that the decrease in the cortical bone density at the medial trochanter region leads to an increased risk of pathological fracture. Therefore, a previously undocumented risk factor for pathological fracture in prostate cancer patients is presented.

Denosumab has been shown to be highly effective at suppressing the progression of giant cell tumor of bone (GCTB). However, recent studies have observed a potential increased risk of local recurrence after surgery following the use of denosumab, raising concerns on the use of this agent against GCTB in combination with surgery.We retrospectively reviewed the medical records of 234 patients with GCTB who were surgically treated at multiple institutions from 1990 to 2017. Patient background, tumor characteristics, treatment methods, local recurrence-free survival rate, distant metastasis rate, oncologic outcome, and limb function at final follow-up were analyzed and compared between cases treated with and without denosumab.The 3-year local recurrence-free survival rate was significantly lower in patients who underwent preoperative denosumab therapy (35.3%) compared with those treated without denosumab (79.9%) (P0.001). Among patients who were preoperatively treated with denosumab, those who had a local recurrence all underwent curettage surgery.Preoperative denosumab therapy in combination with curettage surgery was significantly associated with an increased risk of local recurrence in Campanacci grade 3 tumors. Our data suggest that clinicians seeing GCTB patients should be aware to this increased risk when planning preoperative denosumab therapy.

Eribulin is a novel microtubule inhibitor that, similar to other types of microtubule inhibitors, induces apoptosis by inhibiting the mitotic division of cells. Besides this direct effect on tumor cells, previous studies have shown that eribulin has the potential to induce tumor vascular remodeling in several different cancers; however, the mechanisms underlying this phenomenon remain unclear. In the present study, we aimed to elucidate whether eribulin is effective against synovial sarcoma, a relatively rare sarcoma that often affects adolescents and young adults, and to histologically investigate the microstructure of tumor vessels after the administration of eribulin. We found that eribulin exhibits potent antitumor activity against synovial sarcoma in a tumor xenograft model and that tumor vessels frequently have intervascular pillars, a hallmark of intussusceptive angiogenesis (IA), after the administration of eribulin. IA is a distinct form of angiogenesis that is involved in normal developmental processes as well as pathological conditions. Our data indicate that IA is potentially involved in eribulin-induced vascular remodeling and thereby suggest previously unacknowledged role of IA in regulating the tumor vasculature after eribulin administration.

Introduction Several prognostic factors for survival in synovial sarcoma have been proposed, but the role of adjuvant chemotherapy and radiotherapy is a matter of debate. The study aim was to clarify the effect of high-dose ifosfamide-containing chemotherapy and adjuvant radiotherapy for patients with localized synovial sarcoma. Materials and methods Five tertiary musculoskeletal oncology hospitals participated in this retrospective study. The records of the patient diagnosed with synovial sarcoma without metastasis at diagnosis from 1990 to 2011 have been collected and reviewed. Overall, distant failure-free, and local failure-free survivals were calculated, and prognostic factors for each survival were evaluated by performing univariate and multivariate analyses. Results A total of 162 patients were enrolled in this study with a median follow-up period of 67 months (range, 5-267 months) for all surviving patients. The 5-year overall, distant failure-free, and local failure-free survival rates were 79.7%, 66.3%, and 98.4%, respectively. Univariate analyses demonstrated that high-dose ifosfamide-containing chemotherapy was significantly associated with better overall (p = 0.014) and distant failure-free survival (p = 0.0043) than that of low-dose or no ifosfamide-containing chemotherapy if we analyzed only patients with tumors >5 cm in size. Addition of radiotherapy was not a significant prognostic factor for overall survival in the univariate and multivariate analyses, but it did improve the overall survival of the patients with R1 resection (p = 0.053). Conclusion Patients with localized synovial sarcoma >5 cm in size had better overall and distant failure-free survival after receiving adjuvant chemotherapy containing high-dose ifosfamide comparing to low-dose or no ifosfamide-containing chemotherapy. The addition of adjuvant radiotherapy was beneficial for the patients who received R1 resection. Alternatively, adjuvant radiotherapy could be avoided for patients who achieved an R0 margin.

Spontaneous regression of sarcoma is exceedingly rare. A 62-year-old male presented with myxofibrosarcoma of the thigh which regressed after open biopsy. Treatment strategy for this condition is not well-documented in the literature. In this report, we describe the case of a spontaneously regressed myxofibrosarcoma successfully treated by resection where the extent of the tumor was determined from the initial MRI. This case demonstrates that myxofibrosarcoma has the potential to regress spontaneously, and astute awareness of this phenomenon is necessary for appropriate management of this condition.

To identify the characteristic magnetic resonance imaging (MRI) findings in angioleiomyoma and to clarify its relationship with histopathological findings. We retrospectively analyzed the MRI findings and pathological subtypes in 25 patients with subcutaneous angioleiomyoma of the extremities. Based on the previous reports, MRI findings that could be characteristic of angioleiomyoma were extracted. According to the World Health Organization classification, all cases were classified into three pathological subtypes: solid, venous, and cavernous. The relationship between MRI findings and pathological subtypes was analyzed. The pathological subtypes were solid (n = 10), venous (n = 11), and cavernous (n = 4). The following MRI findings were observed: (a) hypo- or iso-intense linear and/or branching structures on a T2-weighted image (positive total/solid/venous/cavernous: 19/5/10/4, respectively), which we defined as “dark reticular sign”; (b) peripheral hypointense rim on a T2-weighted image (positive total/solid/venous/cavernous: 19/7/8/4, respectively); and (c) presence of any adjacent vascular structures (positive total/solid/venous/cavernous: 6/3/3/0, respectively). Chi-square test showed a significant relationship between dark reticular sign and pathological subtypes (p = 0.0426). The dark reticular sign was found more frequently in the venous and cavernous types than in the solid type. The other MRI findings did not reveal a significant relationship between pathological subtypes. We present the largest case series exploring MRI findings in angioleiomyoma. The dark reticular sign was a characteristic MRI finding of angioleiomyoma and was seen in most of the venous and cavernous types, which may facilitate preoperative diagnosis.

Osteosarcoma is the most common primary bone tumor that mainly affects adolescents and young adults. Although standard treatment modality can achieve up to 60-70% 5-year survival rate, there has not been any substantial improvement over the past four decades. Furthermore, those presenting with pulmonary metastatic lesions often undergo a highly unfavorable clinical course. Therefore, there is a severely unmet clinical need to provide a more effective treatment for patients with osteosarcoma. In this study, we show that trabectedin, a chemotherapeutic agent approved for soft tissue sarcomas, significantly suppresses pulmonary metastasis in a mouse osteosarcoma xenograft model. In vitro experiments revealed that trabectedin suppresses cell migration potentially by downregulating the activity of ERK1/2, intracellular molecules that are critically involved in the regulation of cell motility. Collectively, our data may provide a basis for further investigation of trabectedin on the potential use for osteosarcoma patients who are at great risk of pulmonary metastasis. This article is protected by copyright. All rights reserved.

Nodular hidradenoma (NH) is a benign adnexal tumor that arises from either eccrine or apocrine sweat glands. NH can originate from any cutaneous site, but the most common sites are the head and anterior surface of the trunk, with very rare cases in the extremities. Long-standing NH has been reported to undergo malignant transformation to malignant NH (MNH); however, its occurrence in the lower leg is extremely rare with only one other case reported to date. In this report, we present a rare case of MNH occurring in the lower leg which was resected with the intent to make a diagnosis. At the final follow-up after 11 months, no local recurrence or metastasis has been observed.

Chondrosarcoma is the thirdmost frequentmalignant neoplasm of the bone after osteosarcoma and multiple myeloma, and comprises approximately 20% of all primary malignant bone tumor [1]. It is a chondroid neoplasm most commonly affecting the pelvis, humerus, femur and rib. The small bones of the hand and foot are rarely affected, reportedly less than 1%, although hand is significantly more prevalent. The etiological background of chondrosarcoma genesis remains largely unknown. Down syndrome is characterized by trisomy of chromosome 21 occurring in 1 out of every 700 births [2]. It has been postulated that lower frequency of solid cancer in Down syndrome is possibly due to chromosome 21 trisomy coding for various antitumor proteins [3]. In this report, we present a rare case of chondrosarcoma arising in the proximal phalanx of the small toe in a Down syndrome male, with a review of the literature. The patient and his family were informed that data from the case would be submitted for publication, and gave their consent.

Purpose To assess the clinical importance in the feature change in giant cell tumors of the bone (GCTB) after denosumab treatment, detected by MRI. Methods In 12 patients, MRI and CT of GCTB obtained before and after the treatment retrospectively compared. The tumor size, the signal intensity (SI) ratio between the solid part of the GCTB and muscle, cystic part size, gadolinium enhancement and apparent diffusion coefficient (ADC) value were measured on MRI. The bone formation in the tumor was observed on CT and X-ray. Results The mean number of denosumab injections was 19 ± 10. The follow-up period was up to 2 years. One case showed partial remission, while the other 11 cases were stable. A mean SI ratio on T2-weighted image statistically significantly decreased from 3.9 to 1.9 after the treatment. A cystic component in the tumor was observed in five cases before the treatment, and the diameter of the cystic part decreased after the treatment in 80% of cases (4/5). All the tumors showed contrast enhancement on T1-weighted image pre- and post-treatment (11/11). The averaged ADC values were 1.52 × 10-3 mm2/s before and 1.44 × 10-3 mm2/s after the treatment (P = 0.63). Bone formation in the tumor was observed in 58% of cases (7/12). Conclusion The decrease of SI ratio on T2-weighted image, shrinkage of cystic part and bone formation should be regarded as the effectiveness of denosumab treatment despite of no substantial change in the tumor size.

Denosumab is a monoclonal antibody that has been approved to treat osteoporosis, skeletal metastasis, and giant cell tumor of bone in skeletally mature patients. Due to its potential adverse effects on normal bone growth, its use has not yet been approved in skeletally immature patients; however, the use of this agent in such patients with overt or dysregulated bone resorptive conditions has been explored in recent years. While most studies have proven the effectiveness of denosumab in controlling the progression of various disorders in skeletally immature patients, they have also revealed that refractory hypercalcemia often follows the discontinuation of denosumab treatment, raising a concern over the use of this agent in these patients. Thus, this study was designed to better understand the pathology of this condition through a systematic review of the published literature. Our analysis suggests that this condition has a potential male predisposition, that there is a correlation between the duration of denosumab treatment and patient age, and that this condition often occurs within 3 months after the last administration of denosumab in skeletally immature patients but is significantly less likely in adults. These results may further underscore that high bone formation and bone turnover rates are critically associated with hypercalcemia after the discontinuation of denosumab. In contrast, given that not all skeletally immature patients develop hypercalcemia, it is probable that other unidentified factors are involved in the pathology of this condition., Highlights • Rebound hypercalcemia often follows denosumab cessation in juveniles. • Although relatively rare, rebound hypercalcemia can occur in adults. • Rebound hypercalcemia may have a male predisposition in juveniles. • Treatment duration of denosumab required to trigger hypercalcemia correlates with age. • Onset of hypercalcemia is significantly earlier in juveniles than in adults.

Background Subcutaneous malignant tumors are often treated by non-specialized clinicians in musculoskeletal oncology. While the resection of subcutaneous tumors appears technically feasible, unplanned resection of malignant tumors can result in a devastating clinical outcome. The aim of this study was to evaluate the potential estrangement in the awareness of and the treatment strategy for the patients with subcutaneous soft tissue tumors between musculoskeletal oncologists and non-specialized clinicians. Methods A questionnaire probing the clinical assessment of subcutaneous tumors was sent to orthopedic surgeons, dermatologists, plastic surgeons, and general surgeons. Results of the questionnaire were statistically analyzed. Results One hundred sixteen clinicians out of 150 responded to the questionnaire; the response rate was 77.3%. Among those, 46 clinicians had treated subcutaneous tumors. Thirty-nine of these 46 clinicians (27 musculoskeletal oncologists and 12 non-specialized clinicians) preoperatively performed enhanced MRI for diagnostic evaluation. Preoperative incisional biopsy to confirm the pathological diagnosis was performed by 36 of the 46 clinicians (29 musculoskeletal oncologists and seven non-specialized clinicians). These results indicate that musculoskeletal oncologists perform preoperative enhanced MRI (P = 0.08) and biopsy (P < 0.01) more frequently than non-specialized clinicians. The recognition rate of 'myxofibrosarcoma' was 60.8% among clinicians with an experience with sarcoma treatment (25 musculoskeletal oncologists and three non-specialized clinicians). The recognition rate of 'myxofibrosarcoma' between musculoskeletal oncologists and non-specialized clinicians was statistically significant (P < 0.01). Conclusions Preoperative evaluations for subcutaneous tumors are more often inappropriate in non-specialized clinicians than those who are. Therefore, it will be mandatory to raise the awareness of this condition to improve the clinical outcome of patients with subcutaneous tumors.

Solitary metastasis of a carcinoma to carpal bone is extremely rare. Metastases of renal cell carcinoma (RCC) usually occur in a multiple fashion and there has been no report to date of a solitary metastasis to trapezium from RCC. The tumor was excised and reconstructed with iliac bone transplantation. 2 years and 6 months after surgery, there is no local recurrence with minimal functional loss.

Thymoma is the most common thymic epithelial tumor whose classification was first introduced in 1999. Type B2 thymoma is considered a moderate/high-risk tumor; however, extrathoracic metastases are extremely rare with limited reports to date. In this report, we present a rare thymoma metastasis to the semimembranosus muscle, which was resected with a wide margin after confirmation by open biopsy. At the final follow-up after 1 year, no local recurrence has been observed.

Background: Hibernoma is a rare, benign, soft tissue tumor arising from brown fat that cannot be distinguished from other lipogenic tumors on computed tomography and magnetic resonance imaging (MRI) scans. On the other hand, the image of hibernoma on 18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) is different from that of other lipogenic tumors. However, fewer studies have investigated the typical features of hibernoma on PET scans. We present the case of a hibernoma that was incidentally detected on 18F-FDG-PET. Case Presentation: A 48-year-old Asian man underwent 18F-FDG-PET for routine follow-up of gastric cancer. The patient reported a painless soft mass on the upper arm that had persisted for several years. On 18F-FDG-PET, the mass showed a maximum standardized uptake value of 9.6. The mass showed high intensity on T1- and T2-weighted MRI scans, and showed focally enhanced septa after gadolinium administration. The mass was surgically resected. Histopathologically, the mass was composed of brown adipose cells characteristic of hibernoma. His postoperative course was uneventful, and there was no local recurrence at the final 24-month follow-up. Conclusion: Hibernoma showed strong uniform accumulation on 18F-FDG-PET, suggesting that 18F-FDG-PET would be a useful modality for the differential diagnosis of hibernoma versus other lipogenic tumors.

Fibrous dysplasia (FD) is a monostotic or polyostotic benign bone lesion with spindle-cell proliferation in woven bone and stroma. Rarely, cartilaginous differentiation can be seen in the lesions of FD. FD with massive cartilaginous differentiation is called fibrocartilaginous dysplasia (FCD) and is considered a rare variant of FD. Although pathological findings of FD show irregular immature bone formation without osteoblastic rimming in fibrous tissue, and rarely show very small amounts of cartilage, histological images of FCD are said to show that cartilage with a relatively high cell density is present in the majority and that FD-like findings are seen in parts of it. The most characteristic feature of FCD on images is calcification in the lesions reflecting cartilaginous tissue. On the other hand, typical radiographic findings of FD include shadows with a ground-glass appearance and thinning and bulging of the cortical bone, the observation if calcification is not usual. Therefore, in the diagnosis of FCD, differentiation from multiple enchondromatosis, Ollier disease, chondrosarcoma, and chondrosarcoma secondary to FD is necessary, and it seems important to make a careful diagnosis based not only on the pathological findings but also on imaging and clinical findings. Herein, we report on a case of FD of the proximal femur associated with intralesional extensive cartilaginous differentiation in which a pathological fracture occurred during follow-up, with a review of the literature.

Oligoarticular juvenile idiopathic arthritis (JIA) is one of the most common subtypes of JIA, which, by definition, affects fewer than 5 joints during the course of the disease1. This condition typically involves the large joints of children and lacks systemic symptoms. Here we present a case of oligoarticular JIA that presented with characteristic intraarticular rice bodies. A 5-year-old girl was brought to the orthopedic …

Osteoid osteoma (OO) usually occurs in the extremities of young adults. The tumor can arise in any part of the skeletal tissue; however, it is rarely found in the rib, with limited reports to date. In this report, we present a rare case of OO arising in the rib, which was successfully treated under computed tomography guidance with minimal invasiveness. At the final follow-up after 4 years, no local recurrence was observed.

Epithelioid sarcoma is a rare soft tissue sarcoma and usually resistant to chemotherapy. It has high rates of local recurrence and distant metastasis, and the prognosis after metastasis is poor. We report a case of multiple lung metastases of an epithelioid sarcoma originating in the inguinal area that we treated with the multikinase inhibitor pazopanib. The patient was a 38-year-old male who began to experience discomfort in his left inguinal area. Magnetic resonance imaging showed a tumor extended from the medial aspect of the wing of the left ilium along the iliopsoas muscle to its site of insertion on the femur. The histopathological diagnosis with a biopsy was proximal-type epithelioid sarcoma. Although a positron emission tomography examination showed fluorodeoxyglucose accumulation in the left inguinal tumor, there was no distant metastasis. Wide resection by a combined iliac resection procedure was performed. Twelve months after surgery, computed tomography revealed multiple nodules and a diagnosis of bilateral multiple lung metastases was made. Treatment with pazopanib 800 mg was started. After 2.5 months of treatment, a clear reduction in the size of the pulmonary metastases was shown. Thirty months after the start of pazopanib treatment, most of the metastases have disappeared, and no development of new lesions has been seen. Therefore, it appeared that pazopanib was capable of serving as one of the choices of therapeutic agents that should be taken into consideration for the treatment of advanced epithelioid sarcoma.

BACKGROUND We conducted a nationwide survey of prosthetic reconstruction using a constrained-type hip tumor prosthesis (C-THA) following resection of periacetabular tumors. METHODS Eighty patients with periacetabular tumors underwent wide resection and prosthetic reconstruction using C-THA at JMOG-affiliated institutions (39 males and 41 females; mean age, 46.7 years; mean follow-up period, 65 months). Primary bone or soft tissue sarcoma accounted for 75% of the cases. Adjuvant radiotherapy and chemotherapy were performed for 12 and 37 patients, respectively. RESULTS There were 21 local recurrences (26%), necessitating amputation in 2 patients. Other postoperative complications included deep infection in 31 patients (39%), delayed wound healing in 25 (31%), and prosthesis-related complications requiring surgery in 7 (9%). Removal of the prosthesis was required in 23 patients (29%) (deep infection (n = 20), local recurrence resulting in amputation (n = 2), and outer cup displacement (n = 1). Patients whose abductor muscle was conserved or who underwent functional abductor muscle reconstruction showed significantly longer prosthesis survival. No postoperative wound complications occurred in three recent patients undergoing wound management with a RAM flap. The mean MSTS score was 43%. CONCLUSIONS We analyzed the outcome of 80 patients with periacetabular tumors undergoing C-THA reconstruction. The rates of postoperative complication were still high, but comparable to those in previous studies. Our results suggest wound management using a RAM flap is useful for reducing wound complications.

Segmental bone transport (SBT) is a revolutionary method for treating extensive bone defects, and it is in wide clinical use. Although external fixation is generally used to perform SBT, it is associated with problems such as complications due to pin placement and limitations of the amount and rate of lengthening. As a way to overcome these problems we developed a novel intramedullary (IM) nail for SBT that minimizes damage to the surrounding tissue and improves the amount and rate of bone lengthening. The purpose of this study was to perform SBT in the femur of beagle dogs using the novel IM nail that we devised, and to evaluate the morphology and quality of the regenerated bone and circulation status in the surrounding tissue. We also considered the possibilities and limitations of the IM in regard to clinical application.This experiment was conducted on six beagle dogs. The novel IM nail we devised was inserted into the marrow cavity of the femur, and a 30-mm bone defect was created. After a 7-day postoperative waiting period, a bone segment was transported by 1.0 mm per day in two 0.5-mm increments. Because the nail broke in two dogs, they received only partial elongation by 15 mm over a 15-day period, with a 15-mm defect remaining, whereas full elongation by 30 mm in 30 days was performed in the other four dogs. The elongation was followed by a 30-day bone hardening period.The macroscopic and histological results demonstrated that high-quality, new bone had replaced the 30-mm bone defect created in the femur of all six dogs. The density and number of blood vessels that had penetrated the elongated segment of bone from the surrounding muscles was greater than in the corresponding segment of the contralateral femur, which served as a control. The results imply that the traction stimulus induced vigorous angiogenesis in the surrounding tissue.We concluded that this method has tremendous potential for clinical application, and will overcome the limitations of conventional external fixators.

Background Osteoid osteoma accounts for approximately 10% of all benign bone tumors. The most common sites of osteoid osteoma are the subcortical shaft and metaphyses of long bones, but any other skeletal bone site can be involved. The acetabulum is a rare site according to past reports. This site presents challenges to optimal management because it is anatomically difficult to approach, and because its rarity leads to limited experience with therapeutic procedures. Here, we report for the first time a rare case of osteoid osteoma in the acetabulum that was successfully treated via resection of the nidus and ablation using a standard electrosurgical generator under computed tomographic guidance. Case presentation A 9-year-old Japanese girl presented at a clinic with left hip pain without apparent cause for 1 month. She was diagnosed as having coxitis simplex. However, her pain did not change for 1 year and she was admitted to another hospital where osteoid osteoma in her left acetabulum was suspected. She was then referred to our hospital approximately 1 year after first symptom presentation, where she presented with severe left hip pain and was completely unable to walk. Computed tomography examinations revealed a well-demarcated 5 mm mass with bone sclerosis in her left acetabulum. The mass was characterized by low intensity on T1 and high intensity on T2 magnetic resonance images. These findings were consistent with osteoid osteoma of left acetabulum. She underwent computed tomography-guided resection of nidus and ablation using a standard electrosurgical generator. A histological examination confirmed acetabular osteoid osteoma. Complete pain relief was achieved after the procedure and she experienced no complications. She could walk without any pain at the final follow-up 1 year post-treatment and no local recurrence was observed. Conclusions We successfully treated acetabulum osteoid osteoma without any symptom recurrence by computed tomography-guided resection and ablation using a standard electrosurgical generator. In addition, we preserved our patient’s sciatic nerve and triradiate cartilage. Our report provides evidence that a computed tomography-guided procedure should be considered the treatment of choice for osteoid osteoma of the acetabulum because it is a less invasive alternative to en bloc resection.

A 34-year-old man with intermittent chest pain had a 60-mm mass in the anterior mediastinum. A CT-guided needle biopsy revealed that the tumor was composed of atypical small cells and was positive for HMB-45 without cytoplasmic melanin pigmentation. These results suggested a diagnosis of malignant melanoma (MM) or clear cell sarcoma (CCS). EWS gene rearrangement was detected by fluorescence in situ hybridization, resulting in the definite diagnosis of CCS. Sarcomas originating in the mediastinum account for only 1 % of all sarcoma cases. CCS is a rare soft tissue sarcoma, which usually occurs in the tendons and aponeuroses and is often misdiagnosed as MM because of similar immunophenotypes. There is only one reported case of a primary CCS of the mediastinum. There is no standard treatment for CCS, but for metastatic MM, dacarbazine, ipilimumab, and BRAF-inhibitors can be treatments of choice. Thus, differential diagnoses are important to determine treatment strategies. Meticulous observation of skin lesions and pathological and molecular diagnoses, including EWS gene rearrangement, is recommended in cases with mediastinal tumors suspected of MM or CCS.

Mesenchymal chondrosarcoma (MC) is an extremely rare subtype of chondrosarcoma. A tumor specific fusion gene, HEY1-NCOA2 fusion, was recently identified in this tumor. The finding raises the possibility that the diagnosis of MC can be improved by examining the fusion gene. In the present study, we aimed to evaluate the efficacy of fluorescence in situ hybridization (FISH) in detecting HEY1-NCOA2 fusion for the diagnosis of MC. Specimens from 10 patients diagnosed with MC were used for the study. Dual-color FISH was performed using two different probes that specifically hybridize to HEY1 and NCOA2, respectively. Fusion signals were identified in all but two specimens, in which no signal was detected, presumably because of inadequate sample preparation. In accordance with results of a previous study, FISH analysis was highly sensitive in detecting HEY1-NCOA2 fusion in adequately prepared MC samples. The current study adds further support for the use of HEY1-NCOA2 fusion as a valid diagnostic marker for MC.