David Thomas

Recurrent EWSR1 gene rearrangements characterise a select group of bone and soft tissue tumours. In our routine diagnostic practice with fluorescence in situ hybridisation (FISH), we have occasionally observed EWSR1 gene rearrangements in tumours not classically associated with EWSR1 translocations. This study aimed to review our institutional experience of this phenomenon and also to highlight the occurrence of unusual EWSR1 FISH signals (i.e. 5' centromeric region or 3' telomeric region signals) that do not fulfill the published diagnostic criteria for rearrangements. Using an EWSR1 break-apart probe, we performed FISH assays on formalin-fixed paraffin embedded tissue sections from 135 bone and soft tissue specimens as part of their routine diagnostic workup. EWSR1 gene rearrangements were identified in 51% of cases, 56% of which also showed an abnormal FISH signal pattern (in addition to classically rearranged signals). However, atypical FISH signals were present in 45% o...

For the past 30 years, improvements in the survival of patients with osteosarcoma have been mostly incremental. Despite evidence of genomic instability and a high frequency of chromothripsis and kataegis, osteosarcomas carry few recurrent targetable mutations, and trials of targeted agents have been generally disappointing. Bone has a highly specialized immune environment and many immune signalling pathways are important in bone homeostasis. The success of the innate immune stimulant mifamurtide in the adjuvant treatment of non-metastatic osteosarcoma suggests that newer immune-based treatments, such as immune checkpoint inhibitors, may substantially improve disease outcome.