Background Although proteoglycan (PG) is one of the major components of cartilage matrices, its biological function is not fully elucidated. Methods The objectives of this study were to investigate the proliferation and differentiation of chondrocytes embedded in atelocollagen gel with exogenous cartilage PG (PGatelocollagen gel) in vitro, and also to evaluate the repair of cartilage defects by PG-atelocollagen gel in vivo. In the in vitro study, rabbit chondrocytes were cultured in the PGatelocollagen gel. Cell proliferation and mRNA expression levels were measured, and gels were histologically evaluated. In the in vivo study, cultured PG-atelocollagen gel containing chondrocytes were transplanted into full-thickness articular cartilage defects in rabbit knees, and evaluated macroscopically and histologically. Results For the in vitro study, chondrocyte proliferation in 5.0 mg/ml PG-atelocollagen gel was enhanced, and the gene expression of Col2a1 and Aggrecan were decreased.In contrast, chondrocyte proliferation in 0.1 and 1.0 mg/ml PG-atelocollagen gel was not enhanced. The gene expression of Aggrecan in 0.1 and 1.0 mg/ml PG-atelocollagen gel was increased. For the in vivo study, the histological average total score of the 0.1 mg/ml PG-atelocollagen gel was significantly better than that of the group without PG. Conclusions Although the appropriate concentration of PG has not been defined, this study suggests the efficacy of PG for cartilage repair.

Pure intraosseous arteriovenous malformation (AVM) in a limb bone is extremely rare. Furthermore, there is currently insufficient information on the diagnostic and therapeutic strategies for pure intraosseous AVMs. We herein report a case of pure intraosseous AVM of the proximal femur occurring in a patient with polyostotic fibrous dysplasia. The patient was a 39-year-old woman who presented with pain in the right thigh. Plain radiographs and computed tomography scans revealed a medullary lytic lesion with expansion and thinning of the bone cortex in the right proximal femur, mimicking a primary bone tumor. Magnetic resonance imaging (MRI) examination revealed intramedullary signal voids and feeding arteries arising from the deep femoral artery. A non-surgical approach using embolization and denosumab achieved satisfactory results, which included complete obliteration of the AVM, increased cortical thickness of the right proximal femur, and attenuation of the high-turnover bone metabolism 1 year later. Careful review of MRI images is crucial for distinguishing between bone tumors and intraosseous AVM, which exhibit signal voids and feeding arteries, in order to avoid unnecessary interventions such as bone biopsy or surgery.

The present report describes a case in which teriparatide, which is widely used to treat osteoporosis, may have accelerated the growth of an undiagnosed pre-existing bone tumor of the femur. A 76-year-old woman visited hospital with pain in the right thigh after falling from a ladder. A non-pathological femoral shaft fracture was diagnosed by plain radiography. There were no findings of pathological fracture on the examination. In addition, the patient underwent intramedullary femoral nail fixation and started teriparatide treatment for osteoporosis. The teriparatide was discontinued after 2 months due to nausea. A total of 6 months after surgery, the woman visited Hirosaki University Hospital with abnormal swelling of the right thigh. Following a diagnosis of high-grade malignant mesenchymal bone tumor by needle biopsy, the patient underwent right hip disarticulation. Pathological examination provided a definitive diagnosis of osteoblastic osteosarcoma. The present case is a reminder that teriparatide may accelerate the growth of a pre-existing malignant tumor and that fractures, particularly in elderly patients, should be screened for pathological fracture prior to administering teriparatide.

This retrospective multicenter study aimed to analyze the clinical features and prognosis of 24 patients diagnosed with LGMS between 2002 and 2019 in the Japanese sarcoma network. Twenty-two cases were surgically treated and two cases were treated with radical radiotherapy (RT). The pathological margin was R0 in 14 cases, R1 in 7 cases, and R2 in 1 case. The best overall response in the two patients who underwent radical RT was one complete response and one partial response. Local relapse occurred in 20.8% of patients. Local relapse-free survival (LRFS) was 91.3% at 2 years and 75.4% at 5 years. In univariate analysis, tumors of 5 cm or more were significantly more likely to cause local relapse (p < 0.01). In terms of the treatment of relapsed tumors, surgery was performed in two cases and radical RT was performed in three cases. None of the patients experienced a second local relapse. Disease-specific survival was 100% at 5 years. A wide excision aimed at the microscopically R0 margin is considered the standard treatment for LGMS. However, RT may be a viable option in unresectable cases or in cases where surgery is expected to cause significant functional impairment.

The initial diagnostic distinction between benign and malignant soft tissue tumors is critical for decisions regarding the appropriate course of treatment. The current study aimed to evaluate the vascularity and elasticity of soft tissue tumors by superb microvascular imaging and shear wave elastography using ultrasonography (US), to determine their usefulness in distinguishing malignant soft tissue tumors, and to further establish the diagnostic accuracy and usefulness of a scoring system (SS) based on these evaluations. The present study used 167 lesions of soft tissue tumors examined by US prior to biopsy, surgery and pathological tissue diagnosis. The vascularity index (VI) and the maximal shear velocity (MSV), as indices of vascularity and elasticity respectively, were evaluated using US. The tumor size and depth were also evaluated via magnetic resonance imaging (MRI). Based on the odds ratio of these parameters determined by multivariate logistic regression analysis, an original SS was established to identify the malignancy of soft tissue tumors. VI and MSV exhibited significantly high values for malignant tumors. Tumor size was also significantly larger for malignant than benign tumors. The areas under the curves (AUCs) of the receiver operating characteristic analysis for VI, MSV and tumor size were 0.75, 0.84 and 0.69, respectively, indicating that these methods were effective for the diagnosis of malignancy. An original SS consisting of VI, MSV and tumor size, excluding tumor depth, was established, and revealed an AUC value of 0.90, with 93.6% sensitivity and 79.2% specificity for malignancy distinction. US evaluation of vascularity and elasticity was an effective technique to distinguish malignant soft tissue tumors, and the current SS based on US evaluations including tumor size via MRI demonstrated a high diagnostic accuracy for malignant soft tissue tumors.