A fusion between fibronectin 1 (FN1) and activin receptor 2A (ACVR2A) has been reported previously in isolated cases of the synovial chondromatosis. To analyze further and validate the findings, we performed FISH and demonstrated recurrent FN1–ACVR2A rearrangements in synovial chondromatosis (57%), and chondrosarcoma secondary to synovial chondromatosis (75%), showing that FN1 and/or AVCR2A gene rearrangements do not distinguish between benign and malignant synovial chondromatosis. RNA sequencing revealed the presence of the FN1–ACVR2A fusion in several cases that were negative by FISH suggesting that the true prevalence of this fusion is potentially higher than 57%. In soft tissue chondromas, FN1 alterations were detected by FISH in 50% of cases but no ACVR2A alterations were identified. RNA sequencing identified a fusion involving FN1 and fibroblast growth factor receptor 2 (FGFR2) in the case of soft tissue chondroma and FISH confirmed recurrent involvement of both FGFR1 and FGFR2. These fusions were present in a subset of soft tissue chondromas characterized by grungy calcification, a feature reminiscent of phosphaturic mesenchymal tumor. However, unlike the latter, fibroblast growth factor 23 (FGF23) mRNA expression was not elevated in soft tissue chondromas harboring the FN1–FGFR1 fusion. The mutual exclusivity of ACVR2A rearrangements observed in synovial chondromatosis and FGFR1/2 in soft tissue chondromas suggests these represent separate entities. There have been no reports of malignant soft tissue chondromas, therefore differentiating these lesions will potentially alter clinical management by allowing soft tissue chondromas to be managed more conservatively.

This study examines the presentation, management and outcomes of a series of 10 patients with giant lipomatous tumours (defined as greater than 5 cm diameter) of the hand and forearm who presented to our orthopaedic oncology service. All patients underwent local staging and were discussed at our multidisciplinary tumour meeting prior to definitive surgery. In all cases, neurovascular structures required mobilization in order to excise the tumour. Seven of the tumours were benign lipomas and one was a neural fibrolipoma. The other two were well differentiated lipoma-like liposarcomas/atypical lipomatous tumours. Giant lipomas and well differentiated lipoma-like liposarcomas/atypical lipomatous tumours of the hand and forearm present infrequently and a multidisciplinary approach is recommended in the investigation and surgical management of these patients.

Osteoblastoma and osteoid osteoma together are the most frequent benign bone-forming tumor, arbitrarily separated by size. In some instances, it can be difficult to differentiate osteoblastoma from osteosarcoma. Following our recent description of FOS gene rearrangement in these tumors, the aim of this study is to evaluate the value of immunohistochemistry in osteoid osteoma, osteoblastoma, and osteosarcoma for diagnostic purposes. A total of 337 cases were tested with antibodies against c-FOS: 84 osteoblastomas, 33 osteoid osteomas, 215 osteosarcomas, and 5 samples of reactive new bone formation. In all, 83% of osteoblastomas and 73% of osteoid osteoma showed significant expression of c-FOS in the osteoblastic tumor cell component. Of the osteosarcomas, 14% showed c-FOS expression, usually focal, and in areas with severe morphologic atypia which were unequivocally malignant: 4% showed more conspicuous expression, but these were negative for FOS gene rearrangement. We conclude that c-FOS immunoreactivity is present in the vast majority of osteoblastoma/osteoid osteoma, whereas its expression is usually focal or patchy, in no more than 14% of osteosarcoma biopsies. Therefore, any bone-forming tumor cases with worrying histologic features would benefit from fluorescence in situ hybridization analysis for FOS gene rearrangement. Our findings highlight the importance of undertaking a thorough assessment of expression patterns of antibodies in the light of morphologic, clinical, and radiologic features.

Patients who have limb amputation for musculoskeletal tumours are a rare group of cancer survivors. This was a prospective cross-sectional survey of patients from five specialist centres for sarcoma surgery in England. Physical function, pain and quality of life (QOL) outcomes were collected after lower extremity amputation for bone or soft-tissue tumours to evaluate the survivorship experience and inform service provision.Of 250 patients, 105 (42%) responded between September 2012 and June 2013. From these, completed questionnaires were received from 100 patients with a mean age of 53.6 years (19 to 91). In total 60 (62%) were male and 37 (38%) were female (three not specified). The diagnosis was primary bone sarcoma in 63 and soft-tissue tumour in 37. A total of 20 tumours were located in the hip or pelvis, 31 above the knee, 32 between the knee and ankle and 17 in the ankle or foot. In total 22 had hemipelvectomy, nine hip disarticulation, 35 transfemoral amputation, one knee disarticulation, 30 transtibial amputation, two toe amputations and one rotationplasty. The Toronto Extremity Salvage Score (TESS) differed by amputation level, with poorer scores at higher levels (p < 0.001). Many reported significant pain. In addition, TESS was negatively associated with increasing age, and pain interference scores. QOL for Cancer Survivors was significantly correlated with TESS (p < 0.001). This relationship appeared driven by pain interference scores.This unprecedented national survey confirms amputation level is linked to physical function, but not QOL or pain measures. Pain and physical function significantly impact on QOL. These results are helpful in managing the expectations of patients about treatment and addressing their complex needs.Cite this article: Bone Joint J 2015;97-B:1284–90.