There are very few treatments for musculoskeletal tumors, compared to other cancers; thus, novel therapeutic drugs are needed. Pristimerin (PM) is a triterpene compound isolated from plant extracts that reportedly has antitumor effects on various cancers, such as of the breast and prostate. The purpose of this study was to evaluate the antitumor effects of PM on human osteosarcoma cells. Treatment of the human osteosarcoma cell lines, MNNG and 143B, with PM led to a dose-dependent decrease in cell viability. The effects of PM on apoptosis were evaluated with the Annexin V/propidium iodide assay and analysis of caspases 3, 8, and 9 activities. Western blot analysis showed that PM caused a decrease in the expression of Akt, mTOR, and NF-κB. The volumes and weights of human osteosarcoma xenografts decreased significantly with PM treatment. The results of this study revealed that PM can inhibit human osteosarcoma growth in vitro and in vivo, and may be a novel therapeutic agent for the disease.

Ewing’s sarcoma is a primary malignant tumor of bone occurring mostly in childhood. Few effective reconstruction techniques are available after wide resection of Ewing’s sarcoma at the distal end of the tibia. Reconstruction after wide resection is especially difficult in children, as it is necessary to consider the growth and activity of the lower limbs. A 12-year-old Japanese boy had presented with right lower leg pain at age 8 years. Imaging examination showed a bone tumor accompanied by a large extra-skeletal mass in the distal part of his tibia. The tumor was histologically diagnosed as Ewing’s sarcoma. The patient received chemotherapy, followed by wide resection. Reconstruction consisted of a bone transport method involving external fixation of Taylor Spatial Frame. To prevent infection after surgery, the external fixation pin was coated with iodine. One year after surgery, the patient showed poor consolidation of bone, so iliac bone transplantation was performed on the extended bones and docking site of the distal tibia. After 20 months, tibia formation was good. Three years after surgery, there was no evidence of tumor recurrence or metastases; bone fusion was good, and he was able to run. The bone transport method is an effective surgical method of reconstruction after wide resection of a bone tumor at the distal end of the tibia, if a pin can be inserted into the distal bone fragment. Coating external fixation pins with iodine may prevent postoperative infection.

Leiomyosarcoma is a highly malignant soft tissue sarcoma. Most leiomyosarcomas of the extremities metastasize initially to the lungs, with few metastasizing to the liver. Also, it is difficult to diagnose metastases to other regions of the lung during follow-up. The first patient was a 51-year-old Japanese woman diagnosed with a leiomyosarcoma of the left distal femur. She underwent chemotherapy, followed by wide tumor excision and reconstruction using frozen autograft with total knee arthroplasty. Eleven months later, a focal lesion was observed in her right liver, despite the absence of lung metastases. Partial hepatic resection was performed, and the hepatic lesion was diagnosed a metastasis of leiomyosarcoma. Two years later, there has been no evidence of local recurrence. The second patient was a 60-year-old Japanese male diagnosed with a leiomyosarcoma of the left thigh. He underwent preoperative chemotherapy followed by wide excision. Three years later, a focal lesion was found in his medial liver, despite the absence of lung metastases. Partial hepatic resection was performed, and the hepatic lesion was diagnosed as a metastasis of leiomyosarcoma. At the latest follow-up, there has been no evidence of local recurrence. The lung is the most common site of metastases from leiomyosarcomas of the extremeties, because these metastases are hematogenous. Both our patients presented with metastases of the liver, despite the absence of lung metastases. Hepatic metastasis is commonly found in computed tomography (CT) scan. Periodic CT scans of the chest and abdomen are necessary in following-up patients who undergo resection of primary leiomyosarcomas of the extremities.

We report a case of IgG4-positive inflammatory pseudotumor mimicking malignant bone tumor. Biopsy revealed no tumor cells. Surgical excision was performed and an abscess developing beneath the periosteum was observed with Streptococcus constellatus. Preoperative serum IgG4 value of 120 mg/dl normalized postoperatively to 80.6 mg/dl. It was difficult to distinguish inflammatory pseudotumor from sarcoma because it developed under the periosteum. In such cases, it is important to measure blood IgG4 values and perform tissue staining and culturing.

Cryotherapy could stimulate immune responses and induce abscopal effects. A novel technique was developed for treating spinal bone tumors involving the use of frozen tumor-containing autologous bone grafts for anterior spinal reconstruction following total en-bloc spondylectomy, with the aim of activating cryoimmunity. This study focused on analyzing changes in the T-cell receptor (TCR) repertoire after surgery to evaluate T-cell diversity. Blood samples were collected pre- and post-operatively, with subsequent RNA extraction and immunosequencing. Compared to pre-surgery samples, the diversity and abundance of the Complementarity Determining Region 3 regions of the TCR α and β chains decreased, suggesting that more selective clones may have emerged and influenced immune responses. Through TCR repertoire analysis, this study demonstrated that transplantation of frozen tumor-containing autologous bone impacted the immune system. This study is expected to provide a foundation for developing treatments that may enhance immune activation.