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Purpose The role of chemotherapy (CT) and radiotherapy (RT) for management of extraskeletal osteosarcoma (ESOS) remains controversial. We examined disease outcomes for ESOS patients and investigated the association between CT/RT with recurrence and survival. Patients and methods Retrospective review at 25 international sarcoma centers identified patients ≥18 years old treated for ESOS from 1971 to 2016. Patient/tumour characteristics, treatment, local/systemic recurrence, and survival data were collected. Kaplan–Meier survival and Cox proportional-hazards regression and cumulative incidence competing risks analysis were performed. Results 370 patients with localized ESOS treated definitively with surgery presented with mainly deep tumours (n = 294, 80%). 122 patients underwent surgical resection alone, 96 (26%) also received CT, 70 (19%) RT and 82 (22%) both adjuvants. Five-year survival for patients with localized ESOS was 56% (95% CI 51%–62%). Almost half of patients (n = 173, 47%) developed recurrence: local 9% (35/370), distant 28% (102/370) or both 10% (36/370). Considering death as a competing event, there was no significant difference in cumulative incidence of local or systemic recurrence between patients who received CT, RT, both or neither (local p = 0.50, systemic p = 0.69). Multiple regression Cox analysis showed a significant association between RT and decreased local recurrence (HR 0.46 [95% CI 0.26–0.80], p = 0.01). Conclusion Although the use of RT significantly decreased local recurrences, CT did not decrease the risk of systemic recurrence, and neither CT, nor RT nor both were associated with improved survival in patients with localized ESOS. Our results do not support the use of CT; however, adjuvant RT demonstrates benefit in patients with locally resectable ESOS.

INTRODUCTION Low-grade myofibroblastic sarcoma (myofibrosarcoma) is described to be a distinct atypical myofibroblastic tumor often with fibromatosis-like features and predilection for head and neck. Low-grade myofibroblastic sarcoma of bone is extremely rare. PRESENTATION OF CASE A 50-year-old woman was admitted to our hospital because she had experienced right knee pain for 2 years. Plain radiography showed a honeycombed lesion on the right distal femur, and computed tomography showed a bone tumor with cortex destruction invading the soft tissue. A biopsy specimen from the intraosseous lesion showed a hypocellular area of spindle cell proliferation with dense collagen deposition, which is reminiscent of a histological feature of desmoplastic fibroma. However, histological examination of the extraosseous lesion indicated a slightly hypercellular area containing scattered spindle-shaped atypical cells with enlarged nuclei, suggestive of low-grade sarcoma. Spindle-shaped atypical cells were immunohistochemically positive for SMA. A final diagnosis of low-grade myofibroiblastic sarcoma of the bone was made from a surgically resected specimen. DISCUSSION The patient was alive and well with no evidence of disease at 15 months after the surgery without any additional therapy. CONCLUSION Extensive sampling of a tumor may be necessary to determine the true nature of the tumor and to make an accurate diagnosis.

INTRODUCTIONIntraneural lipoma and fibrolipomatous hamartoma of the nerve are rare soft tissue tumors that most commonly occur in the forearm and the wrist, and particularly within the median nerve. When the lesions are large enough, they may cause progressive compression neuropathy. They are distinct entities each other with different clinical and radiological findings and thereby need different surgical treatments.PRESENTATION OF CASEWe report here 3 cases of intraneural lipomatous tumors of the median nerve (1 case of intraneural lipoma and 2 cases of fibrolipomatous hamartoma).DISCUSSIONAll patients were surgically treated successfully with complete excision for intraneural lipoma and with carpal tunnel releases for the both fibrolipomatous hamartomas.CONCLUSIONA careful preoperative planning is necessary for the optimal treatment by distinguishing whether it is a resectable or non-resectable tumor based on the clinical and radiological findings, because they have characteristic findings each other.

A 19-year-old woman was admitted to the hospital with a complaint of right wrist pain. A plain radiograph showed an osteolytic lesion in the right distal radius. Surgical treatment with curettage and bone grafting was performed under the clinical diagnosis of a giant-cell tumor. However, local recurrence was noticed 6 months after the treatment, and the curettage and bone graft were performed again. The histology of the recurrent lesion revealed a malignant giant-cell tumor that was entirely composed of highly atypical stromal cells and tumor giant cells. After a retrospective review of the primary lesion, it was found to also contain a small focus of pleomorphic cells within the conventional giant-cell tumor. Immunohistochemical and genetic analysis revealed p53 overexpression in the tumor giant cells and loss of heterozygosity of p53 gene only in the recurrent tumor; thus, a diagnosis of secondary malignant giant-cell tumor was finally made. The patient underwent systemic chemotherapy along with curettage and cryosurgery using liquid nitrogen. It is now 1 year and 4 months after the last treatment, and the patient is well and alive with no evidence of the disease. Identification of p53 genetic alteration may help in diagnosing malignant giant-cell tumor.

The clinical features of extraskeletal osteosarcoma are not well known. Unlike osteosarcoma of the bone, the efficacy of chemotherapy for extraskeletal osteosarcoma has not been established yet.A multiinstitutional study of extraskeletal osteosarcoma was conducted.A total of 20 patients were enrolled in the study from the Japanese Musculoskeletal Oncology Group institutions. Their ages ranged from 15 to 88 years (mean 50 years). Six lesions were located in the thigh, four in the chest, four in the buttocks, three in the upper arm, and others. UICC surgical stages were II in 5 patients, III in 13, and IV in 2. Surgical resection was performed in 19 patients, and the consequent surgical margin was wide in 15 patients, marginal in 3, and intralesional in 1. The overall 5-year survival rate was 66%. Three patients demonstrated tumor recurrence postoperatively, and the 5-year local control survival rate was 75%. Altogether, 15 patients received chemotherapy, of whom 11 had evaluable responses as follows: complete response in none, partial response in 5 patients, and no change or progressive disease in 6 patients, with a response rate of 45%.Among the patients with extraskeletal osteosarcoma, both the 5-year survival rate and the chemotherapy response rate tended to improve in this study in comparison to the findings published in previous reports. As a result, we believe that treatment regimens that include systemic chemotherapy may be able to improve the prognosis in patients with extraskeletal osteosarcoma.